The Impact of Climate Change on Vegetable Crop Diseases and Their Management: The Value of Phytotron Studies for the Agricultural Industry and Associated Stakeholders

Climate change is having a significant impact on global agriculture, particularly on vegetable crops, which play a critical role in global nutrition. Recently, increasing research has concentrated on the impact of climate change on vegetable crop diseases, with several studies being conducted in phytotrons, which have been used to explore the effects of increased temperatures and CO2 concentrations to simulate future scenarios. This review focuses on the combined effects of temperature and carbon dioxide increases on foliar and soilborne vegetable diseases, as evaluated under phytotron conditions. The influence of climate change on mycotoxin production and disease management strategies is also explored through case studies. The results offer valuable information that can be used to guide both seed and agrochemical industries, as well as to develop disease-resistant varieties and innovative control measures, including biocontrol agents, considering the diseases that are likely to become prevalent under future climatic scenarios. Recommendations on how to manage vegetable diseases under ongoing climate change are proposed to facilitate plants' adaptation to and enhanced against the changing conditions. A proactive and comprehensive response to climate-induced challenges in vegetable farming is imperative to ensure food security and sustainability.

First Report of Gnomoniopsis fragrariae causing leaf spots on strawberry in Italy

Strawberry (Fragaria × ananassa Duch.) is widely cultivated in Italy. During May-June 2022, mild symptoms of an unknown leaf spot disease appeared on 5-10% of June-bearing strawberry (cv. Elodì) plants transplanted in July 2021 in a commercial farm located in the province of Cuneo, North Italy. During September-November 2022, the symptoms appeared also on 10-15% of the plants transplanted in July 2022. The disease was scattered throughout the field, large 600 m2, both on new and senescent leaves. Fungicides (sulphur, Tiovit Jet; penconazole, Topas 10 EC) were applied to the plants according to integrated pest management during the growing period. The disease symptoms were purplish to brown necrotic leaf spots up to 1-3 mm in diameter and chlorotic leaf margins. Black lesions were occasionally observed on the petioles, appearing as small necrotic or larger elongated lesions causing leaf death. Peritechia were observed in planta after about 4 months from sampling and measured (144 to 239 μm and 200 to 291 μm, n = 10). Diseased leaves and petioles from about 10 plants were surface disinfested for 1 min in 1% NaClO, rinsed with sterile water and plated on potato dextrose agar (PDA) amended with 25 mg streptomycin sulphate/liter. A fungus with white cottony colonies was repeatedly recovered and maintained in pure culture on PDA. Biguttulate conidia with rounded ends were measured (4.3 to 8.0 μm and 1.2 to 2.9 μm, average 6.1× 2.3 μm, n = 50) from 21-day old colonies grown in PDA at 22°C and 12 h photoperiod. According to colony and conidia morphology, the isolate was identified as Gnomoniopsis sp. (Walker et al., 2010). The fungal DNA was extracted from a pure culture of one isolate selected as a representative (code FR2-22), by using the E.Z.N.A. Fungal DNA Mini Kit (Omega Bio-Tek, Darmstadt, Germany). The identification was carried out by amplifying and sequencing the internal transcribed spacer (ITS) region and the partial translation elongation factor 1-α (TEF) gene using the primers ITS1/ITS4 and EF-728F/EF2 (Udayanga et al., 2021), respectively. The purified PCR products were sequenced at the BMR Genomics Centre (Padova, Italy) obtaining 551bp (ITS) and 652bp (TEF) sequences deposited in GenBank (Accession nos. OQ179950 and OQ190173, respectively). A BLASTn search of both sequences revealed to be 100% identical to the ITS and TEF loci of Gnomoniopsis fructicola sequences of the isolates VPRI_15547 and CBS 275.51 deposited in GenBank with accession Nos. MT378345 and MT383092. The pathogenicity of the isolate FR2-22 was assessed in two trials by biological tests (3 replicates with 1 plant per replicate/pot) in two greenhouse compartments, kept at temperature 20-24°C and at humidity 80-90%. Healthy leaves of forty-day-old strawberry plants (cv. Elodì) were sprayed with 1-5 x106 conidia/ml obtained from the FR2-22 isolate grown on PDA at 25°C for 20 days. The control (water-sprayed plants) was kept in the same conditions. Small leaf spots similar to the symptoms previously observed in the farm were observed 15 days post inoculation. Furthermore, 30 to 40% of leaves developed symptoms similar to those observed in the field after 25-40 days, while the control remained health. The same fungal isolate was repeatedly reisolated from the affected leaves and petioles and identified based on TEF sequencing. Gnomoniopsis fragariae comb. nov., designed as new name for Gnomoniopsis fructicola (Udayanga et al., 2021), has previously been reported on Fragaria × ananassa plants in Australia and in the USA (Farr and Rossman, 2023). To the best of our knowledge, this is the first report of G. fragariae on strawberry in Italy. The impact of the disease caused by this pathogen could be of high importance in the future of strawberry production in Italy. Healthy propagation material and strict disease management practices in nurseries is a requirement to avoid disease epidemics.

Improving sustainable hydrogen production from green waste: [FeFe]-hydrogenases quantitative gene expression RT-qPCR analysis in presence of autochthonous consortia

BACKGROUND

Bio-hydrogen production via dark fermentation of low-value waste is a potent and simple mean of recovering energy, maximising the harvesting of reducing equivalents to produce the cleanest fuel amongst renewables. Following several position papers from companies and public bodies, the hydrogen economy is regaining interest, especially in combination with circular economy and the environmental benefits of short local supply chains, aiming at zero net emission of greenhouse gases (GHG). The biomasses attracting the largest interest are agricultural and urban green wastes (pruning of trees, collected leaves, grass clippings from public parks and boulevards), which are usually employed in compost production, with some concerns over the GHG emission during the process. Here, an alternative application of green wastes, low-value compost and intermediate products (partially composted but unsuitable for completing the process) is studied, pointing at the autochthonous microbial consortium as an already selected source of implementation for biomass degradation and hydrogen production. The biocatalysts investigated as mainly relevant for hydrogen production were the [FeFe]-hydrogenases expressed in Clostridia, given their very high turnover rates.

RESULTS

Bio-hydrogen accumulation was related to the modulation of gene expression of multiple [FeFe]-hydrogenases from two strains (Clostridium beijerinckii AM2 and Clostridium tyrobutyricum AM6) isolated from the same waste. Reverse Transcriptase quantitative PCR (RT-qPCR) was applied over a period of 288 h and the RT-qPCR results showed that C. beijerinckii AM2 prevailed over C. tyrobutyricum AM6 and a high expression modulation of the 6 different [FeFe]-hydrogenase genes of C. beijerinckii in the first 23 h was observed, sustaining cumulative hydrogen production of 0.6 to 1.2 ml H₂/g VS (volatile solids). These results are promising in terms of hydrogen yields, given that no pre-treatment was applied, and suggested a complex cellular regulation, linking the performance of dark fermentation with key functional genes involved in bio-H₂ production in presence of the autochthonous consortium, with different roles, time, and mode of expression of the involved hydrogenases.

CONCLUSIONS

An applicative outcome of the hydrogenases genes quantitative expression analysis can be foreseen in optimising (on the basis of the acquired functional data) hydrogen production from a nutrient-poor green waste and/or low added value compost, in a perspective of circular bioeconomy.

Biological and molecular interplay between two viruses and powdery and downy mildews in two grapevine cultivars

Grapevine may be affected simultaneously by several pathogens whose complex interplay is largely unknown. We studied the effects of infection by two grapevine viruses on powdery mildew and downy mildew development and the molecular modifications induced in grapevines by their multiple interactions. Grapevine fanleaf virus (GFLV) and grapevine rupestris stem pitting-associated virus (GRSPaV) were transmitted by in vitro-grafting to Vitis vinifera cv Nebbiolo and Chardonnay virus-free plantlets regenerated by somatic embryogenesis. Grapevines were then artificially inoculated in the greenhouse with either Plasmopara viticola or Erysiphe necator spores. GFLV-infected plants showed a reduction in severity of the diseases caused by powdery and downy mildews in comparison to virus-free plants. GFLV induced the overexpression of stilbene synthase genes, pathogenesis-related proteins, and influenced the genes involved in carbohydrate metabolism in grapevine. These transcriptional changes suggest improved innate plant immunity, which makes the GFLV-infected grapevines less susceptible to other biotic attacks. This, however, cannot be extrapolated to GRSPaV as it was unable to promote protection against the fungal/oomycete pathogens. In these multiple interactions, the grapevine genotype seemed to have a crucial role: in 'Nebbiolo', the virus-induced molecular changes were different from those observed in 'Chardonnay', suggesting that different metabolic pathways may be involved in protection against fungal/oomycete pathogens. These results indicate that complex interactions do exist between grapevine and its different pathogens and represent the first study on a topic that still is largely unexplored.

Ligand stabilization and effect on unfolding by polymorphism in human flavin-containing monooxygenase 3

Pharmacogenomics is a powerful tool to prevent adverse reactions caused by different response of individuals to drug administration. Single nucleotide polymorphisms (SNPs) represent up to 90% of genetic variations among individuals. Drug metabolizing enzymes are highly polymorphic therefore the kinetic parameters of their catalytic reactions can be significantly influenced. This work reports on the unfolding process of a phase I drug metabolizing enzyme, human flavin-containing monooxygenase 3 (hFMO3) and its single nucleotide polymorphic variants (SNPs) V257M, E158K and E308G. Differential scanning calorimetry (DSC) indicates that the thermal denaturation of the enzyme is irreversible. The melting temperature (T_m) for the (Wild Type) WT and its polymorphic variants is found to be in a range from 46 °C to 50 °C. Also the activation energies of unfolding (E_a) show no significant differences among all proteins investigated (290-328 KJ/mol), except for the E308G variant that showed a significantly higher E_a of 412 KJ/mol. The presence of the bound NADP⁺ cofactor is found to stabilize all the variants by shifting the main T_m by 4-5 °C for all the proteins, exception made for E308G where no changes are observed. Isothermal titration calorimetry (ITC) was used to characterize the interaction of the protein with NADP⁺ in terms of dissociation constant (K_d), enthalpy (ΔH) and entropy (ΔS). K_d values of 1.6 and 0.7 μM, ΔH of -13.9 Kcal/mol and -16.8 Kcal/mol, ΔS of -20.5 cal/mol/deg, and -28.5 cal/mol/deg were found for V257M and E158K respectively. E308G was found to be unable to bind the NADP⁺ cofactor, a result that is in line with the T_m results. Circular dichroism also confirmed an overall lower stability of E308G, while NADP⁺ was found to give a strong positive shift of the T_m stabilizing the structure of E158K (46.2 to 50.6 °C). Previous data highlighted significant differences in terms of activity among the SNPs of hFMO3. In this work a minor impact of the SNPs was found on the stability of the enzyme in the ligand free form, except for E308G, whereas the binding of NADP⁺ reveals major differences among WT and polymorphic variants that are all measurable in terms of heat capacity, enthalpy and secondary structure content. These data provide the first direct evidence of ligand stabilization effects on hFMO3 that can explain the differences observed in catalytic efficiencies and serve as the starting point for the development of inhibitors of this enzyme.

Characterization of Colletotrichum ocimi Population Associated with Black Spot of Sweet Basil (Ocimum basilicum) in Northern Italy

Black spot is a major foliar disease of sweet basil (Ocimum basilicum) present in a typical cultivation area of northern Italy, including the Liguria and southern Piedmont regions, where this aromatic herb is an economically important crop. In this study, 15 Colletotrichum isolates obtained from sweet basil plants with symptoms of black spot sampled in this area were characterized morphologically and by nuclear DNA analysis using internal transcribed spacers (ITS) and intervening 5.8S nrDNA as well as part of the β-tubulin gene (TUB2) regions as barcode markers. Analysis revealed all but one isolate belonged to the recently described species C. ocimi of the C. destructivum species complex. Only one isolate was identified as C. destructivum sensu stricto (s.s.). In pathogenicity tests on sweet basil, both C. ocimi and C. destructivum s.s. isolates incited typical symptoms of black spot, showing that although C. ocimi prevails in this basil production area, it is not the sole causal agent of black spot in northern Italy. While no other hosts of C. ocimi are known worldwide, the close related species C. destructivum has a broad host range, suggesting a speciation process of C. ocimi within this species complex driven by adaptation to the host.

Expression and role of CYP505A1 in pathogenicity of Fusarium oxysporum f. sp. lactucae

BACKGROUND

Cytochrome P450 enzymes (CYPs) are monooxygenases present in every domain of life. In fungi CYPs are involved in virulence. Fusarium wilt of lettuce, caused by F. oxysporum f. sp. lactucae, is the most serious disease of lettuce. F. oxysporum f.sp. lactucae MSA35 is an antagonistic fungus. Pathogenic formae specialis of F. oxysporum possess a CYP belonging to the new family CYP505. This enzyme hydroxylates saturated fatty acids that play a role in plant defence.

METHODS

Molecular tools were adopted to search for cyp505 gene in MSA35 genome. cyp505 gene expression analysis in pathogenic and antagonistic Fusarium was performed. The enzyme was expressed in its recombinant form and used for catalytic reactions with fatty acids, the products of which were characterized by mass spectrometry analysis.

RESULTS

A novel MSA35 self-sufficient CYP505 is differentially expressed in antagonistic and pathogenic F. oxysporum. Its expression is induced by the host plant lettuce in both pathogenesis and antagonism during the early phase of the interaction, while it is silenced during the late phase only in antagonistic Fusarium. Mass-spectrometry investigations proved that CYP505A1 mono-hydroxylates lauric, palmitic and stearic acids.

CONCLUSIONS

The ability of CYP505A1 to oxidize fatty acids present in the cortical cell membranes together with its differential expression in its Fusarium antagonistic form point out to the possibility that this enzyme is associated with Fusarium pathogenicity in lettuce.

GENERAL SIGNIFICANCE

The CYP505 clan is present in pathogenic fungal phyla, making CYP505A1 enzyme a putative candidate as a new target for the development of novel antifungal molecules.

Ready-to-Eat Salad Crops: A Plant Pathogen's Heaven

The ready-to-eat salad sector, also called fresh-cut or bagged salads, is a fast-growing segment of the fresh-food industry. The dynamism and specialization of this sector, together with the lack of adequate crop rotation, the globalization of the seed market, and climate change, are the main causes of the development of many new diseases that cause severe production losses. Newly detected diseases of the most important crops grown (lettuce, wild and cultivated rocket, lamb's lettuce, chicory, endive, basil, spinach, and Swiss chard) are critically discussed. The management of these diseases represents a formidable challenge, since few fungicides are registered on these minor-use crops. An interesting feature of the ready-to-eat salad sector is that most crops are grown under protection, often in soilless systems, which provide an environment helpful to the implementation of innovative control methods. Current trends in disease management are discussed, with special focus on the most sustainable practices.

Emergence of Leaf Spot Disease on Leafy Vegetable and Ornamental Crops Caused by Paramyrothecium and Albifimbria Species

The genera Paramyrothecium and Albifimbria have been established from the former genus Myrothecium and they generally comprise common soil-inhabiting and saprophytic fungi. Within these genera, only two fungi have been recognized as phytopathogenic thus far: P. roridum and A. verrucaria, both of which cause necrotic leaf spots and plant collapse. Severe leaf necrosis and plant decay have been observed in Northern and Southern Italy on leafy vegetable crops. Thirty-six strains of Paramyrothecium- and Albifimbria-like fungi were isolated from affected plants belonging to eight different species. Based on morphological characteristics, 19 strains were assigned to A. verrucaria, whereas the remaining strains, which mostly resembled Paramyrothecium-like fungi, could not be identified precisely. Molecular characterization of six loci (internal transcribed spacer [ITS], β-tubulin [tub2], calmodulin [cmdA], translation elongation factor 1-alpha [tef1], large subunit ribosomal RNA [LSU], and mitochondrial ATP 6synthase 6 [ATP6]) of the 36 new isolates and three previously ITS-characterized isolates assigned all strains to four species: A. verrucaria, P. roridum, P. foliicola, and P. nigrum. Single and concatenated phylogenetic analyses were conducted, and they clearly distinguished the isolated fungi into four different groups. A. verrucaria, P. roridum, P. foliicola, and P. nigrum were able to induce leaf necrosis singly, and they were confirmed to be the causal agents of the leaf spot disease through pathogenicity assays. The involvement of fungi previously considered saprophytic (i.e., P. foliicola and P. nigrum) in the development of plant disease for the first time deserves particular attention because of the possibility of their transmission by seeds and the limited knowledge of their management with chemicals.

Influence of different biological control agents and compost on total and nitrification-driven microbial communities at rhizosphere and soil level in a lettuce - Fusarium oxysporum f. sp. lactucae pathosystem

AIMS

The response of rhizosphere and bulk soil indigenous microbial communities focusing on nitrifiers was evaluated after the application of different biological control agents (BCAs; Bacillus, Trichoderma, Pseudomonas) and compost in controlling lettuce Fusarium wilt.

METHODS AND RESULTS

Experiments were conducted 'in situ' over two lettuce cropping seasons. Total fungal, bacterial and archaeal populations and the nitrifiers were analysed using quantitative polymerase chain reaction method. The pathogen, Fusarium oxysporum forma specialis lactucae (FOL), Bacillus, Trichoderma and Pseudomonas and three antifungal genes (chiA, 2,4-diacetylphloroglucinol - phlD and HCN synthase - hcnAB genes) were also assessed. Quantitative data were corroborated with disease severity (DS), potential nitrification activity and soil chemical parameters. The application of BCAs and compost resulted in the disease reduction by as much as 69%, confirmed by significant negative correlations between Bacillus subtilis, Trichoderma and Pseudomonas sp. abundances and DS. The FOL presence in the untreated control resulted in the nitrifiers niche differentiation.

CONCLUSIONS

The used treatments were efficient against Fusarium wilt and did not influence negatively the nontarget microbial communities.

SIGNIFICANCE AND IMPACT OF THE STUDY

The use of BCAs and compost appears as an effective and safe strategy to implement sustainable agricultural practices.

Differentiation of Pythium spp. from vegetable crops with molecular markers and sensitivity to azoxystrobin and mefenoxam

BACKGROUND

Pythium species attack various vegetable crops causing seed, stem and root rot, and 'damping-off' after germination. Pythium diseases are prevalently controlled by two classes of fungicides, QoIs with azoxystrobin and phenlyamides with mefenoxam as representatives. The present study aimed to test the sensitivity of six Pythium species from different vegetable crops to azoxystrobin and mefenoxam and differentiating species based on ITS, cytochrome b and RNA polymerase I gene sequences.

RESULTS

The inter- and intra-species sensitivity to azoxystrobin was found to be stable, with the exception of one Pythium paroecandrum isolate, which showed reduced sensitivity and two cytochrome b amino acid changes. For mefenoxam, the inter-species sensitivity was quite variable and many resistant isolates were found in all six Pythium species, but no RNA polymerase I amino acid changes were observed in them. ITS and cytochrome b phylogenetic analyses permitted a clear separation of Pythium species corresponding to globose- and filamentous-sporangia clusters.

CONCLUSION

The results document the necessity of well-defined chemical control strategies adapted to different Pythium species. Since the intrinsic activity of azoxystrobin among species was stable and no resistant isolates were found, it may be applied without species differentiation, provided it is used preventatively to also control highly aggressive isolates. For a reliable use of mefenoxam, precise identification and sensitivity tests of Pythium species are crucial because its intrinsic activity is variable and resistant isolates may exist. Appropriate mixtures and/or alternation of products may help to further delay resistance development. © 2018 Society of Chemical Industry.

Microbiological Parameters in the Primary Production of Berries: A Pilot Study

The primary production of fresh soft fruits was considered to be a suspected critical point for the contamination of frozen berries that were responsible for the large 2013⁻2014 Hepatitis A virus (HAV) outbreak in Europe. In this study, an Italian berries’ production area was studied for its agro-technical characteristics, and the fresh fruits were analyzed for the presence of enteric viruses (HAV and Norovirus (NoV) genogroup I and genogroup II (GGI and GGII)), the enumeration of hygienic quality parameters, and the prevalence of bacterial pathogens. A total of 50 producers were sampled, who specialized in the exclusive or shared cultivation of berries. Escherichia coli was detected in two blackberry samples, whereas HAV and Norovirus were not detected. The samples were negative for Salmonella spp., Listeria monocytogenes, and Shiga toxin-producing Escherichia coli (STEC). The farms’ attributes were not associated with positive samples, apart from the presence of E. coli and the aerobic mesophilic bacteria for blackberry that were statistically correlated. In blueberries, the high aerobic mesophilic count could likely be associated with the resistance of the outer layer to handling. However, the two pathogens (Salmonella spp. and STEC) and the targeted viruses (HAV, NoV GGI and GGII) were not detected, highlighting the low risk of foodborne pathogens and viral contamination at the primary production stage of the berry food chain in the area considered in this pilot study.

Verrucarin A and roridin E produced on rocket by Myrothecium roridum under different temperatures and CO2 levels

The behaviour of Myrothecium roridum, artificially inoculated on cultivated rocket (Eruca sativa), has been evaluated under eight different temperature and CO2 concentration combinations (from 14-18 °C to 26-30 °C and with 400-450 or 800-850 ppm of CO2). The pathogen isolate used for this study was inoculated on rocket and disease severity increased with high temperatures for both CO2 levels. Verrucarin A and roridin E mycotoxins were produced under all the tested temperatures at high CO2 conditions. The maximum level of verrucarin A was found at 14-18 °C and 800-850 ppm of CO2, and the maximum roridin E production was detected at 26-30 °C with 800-850 ppm of CO2. The results obtained in this study show that both the CO2 concentration and the temperature influence disease severity and mycotoxin production in different ways. An increase in temperature, which is favourable for attacks of the pathogen, could induce the spread of M. roridum in temperate regions, and this pathogen could take on even greater importance in the future, considering its ability to produce mycotoxins.

Extended C-band tunable multi-channel InP-based coherent receiver PICs

Fully integrated monolithic, multi-channel InP-based coherent receiver PICs and transceiver modules with extended C-band tunability are described. These PICs operate at 33 and 44 Gbaud per channel under dual polarization (DP) 16-QAM modulation. Fourteen-channel monolithic InP receiver PICs show integration and data rate scaling capability to operate at 44 Gbaud under DP 16-QAM modulation for combined 4.9 Tb/s total capacity. Six channel simultaneous operation of a commercial transceiver module at 33 Gbaud is demonstrated for a variety of modulation formats including DP 16-QAM for >1.2Tbit/s aggregate data capacity.

Grapevine Grafting: Scion Transcript Profiling and Defense-Related Metabolites Induced by Rootstocks

Rootstocks are among the main factors that influence grape development as well as fruit and wine composition. In this work, rootstock/scion interactions were studied using transcriptomic and metabolic approaches on leaves of the "Gaglioppo" variety, grafted onto 13 different rootstocks growing in the same vineyard. The whole leaf transcriptome of "Gaglioppo" grafted onto five selected rootstocks showed high variability in gene expression. In particular, significant modulation of transcripts linked to primary and secondary metabolism was observed. Interestingly, genes and metabolites involved in defense responses (e.g., stilbenes and defense genes) were strongly activated particularly in the GAG-41B combination, characterized in addition by the down-regulation of abscisic acid (ABA) metabolism. On the contrary, the leaves of "Gaglioppo" grafted onto 1103 Paulsen showed an opposite regulations of those transcripts and metabolites, together with the greater sensitivity to downy mildew in a preliminary in vitro assay. This study carried out an extensive transcriptomic analysis of rootstock effects on scion leaves, helping to unravel this complex interaction, and suggesting an interesting correlation among constitutive stilbenes, ABA compound, and disease susceptibility to a fungal pathogen.

Verrucarin A and roridin E produced on spinach by Myrothecium verrucaria under different temperatures and CO2 levels

The behavior of Myrothecium verrucaria, artificially inoculated on spinach, was studied under seven different temperature conditions (from 5 to 35 °C) and under eight different combinations of temperature and CO₂ concentration (14-30 °C and 775-870 or 1550-1650 mg/m³). The isolate used for this study was growing well on spinach, and the mycotoxins verrucarin A and roridin E were produced under all tested temperature and CO₂ conditions. The maximum levels of verrucarin A (18.59 ng/g) and roridin E (49.62 ng/g) were found at a temperature of 26-30 °C and a CO₂ level of 1550-1650 mg/m³. Rises in temperature as well as in temperature and CO₂ concentrations had a significant effect by increasing Myrothecium leaf spots on spinach. The biosynthesis of verrucarin A was significantly increased at the highest temperature (35 °C), while roridin E was influenced by the CO₂ concentration. These results show that a positive correlation between climate condition and macrocyclic trichothecene production is possible. However, because of the ability of M. verrucaria to produce mycotoxins, an increase in temperature could induce the spread of M. verrucaria in temperate regions; this pathogen may gain importance in the future.

Mycotoxin production in liquid culture and on plants infected with Alternaria spp. isolated from rocket and cabbage

Fungi belonging to the genus Alternaria are common pathogens of fruit and vegetables with some species able to produce secondary metabolites dangerous to human health. Twenty-eight Alternaria isolates from rocket and cabbage were investigated for their mycotoxin production. Five different Alternaria toxins were extracted from synthetic liquid media and from plant material (cabbage, cultivated rocket, cauliflower). A modified Czapek-Dox medium was used for the in vitro assay. Under these conditions, more than 80% of the isolates showed the ability to produce at least one mycotoxin, generally with higher levels for tenuazonic acid. However, the same isolates analyzed in vivo seemed to lose their ability to produce tenuazonic acid. For the other mycotoxins; alternariol, alternariol monomethyl ether, altenuene and tentoxin a good correlation between in vitro and in vivo production was observed. In vitro assay is a useful tool to predict the possible mycotoxin contamination under field and greenhouse conditions.

Root Rot of Spinach in Southern Italy Caused by Pythium aphanidermatum

During the spring of 2014, spinach (Spinacia oleracea L.) plants of the cv. Crocodile (Rijk Zwaan, De Lier, The Netherlands), grown in a clay loam soil under commercial greenhouse conditions near Salerno (southern Italy), showed stunting, extensive chlorosis, and root rot. Plants were irrigated by overhead sprinklers using well water. Symptoms first developed 20 days after sowing, at air temperatures of 23 to 30°C, and 35% of plants (approximately 15 million plants in 10 ha) were affected. Roots were severely affected, appeared water-soaked and brown, and were characterized by a soft rot. Eventually, affected plants wilted and collapsed. Fifty fragments, each 1 mm², were excised from symptomatic roots of 10 plants, dipped in a solution containing 1% sodium hypochlorite, rinsed in sterilized water, dried on sterilized paper towel, and plated on both potato dextrose agar (PDA) and the medium BNPRA, which is semi-selective for oomycetes (3). After 5 days of incubation under constant fluorescent light at 22 ± 1°C, 80% of the root sections developed oomycete colonies. One representative isolate, grown for 12 days on V8 agar medium (200 ml V8 Campbell Soup; 15 g agar; 0.5 g CaCO₃; 1 liter distilled water) and observed with a light microscope, showed aseptate hyphae 3.3 to 6.5 (mean 5.5) μm wide. Oogonia were globose, smooth, and 22.2 to 31.0 (average 26.3) μm in diameter. Antheridia were barrel-shaped, while oospores were globose and 17.3 to 22.6 (mean 20.9) μm in diameter. These morphological characters identified the microorganism as a Pythium sp. (4). The internal transcribed spacer (ITS) region of ribosomal DNA (rDNA) of this isolate was amplified using ITS1/ITS4 primers and sequenced. BLAST analysis (1) of the 647-bp segment showed 100% homology with ITS sequences of Pythium aphanidermatum in GenBank (Accession Nos. KJ755088.1, KJ162355.1, KF840479, and KF561235.1). The nucleotide sequence for the Italian spinach isolate was assigned No. KM111256. Pathogenicity tests were performed twice on 20-day-old spinach plants of the cv. Merlo (L'Ortolano, Cesena, Italy), grown in 2-liter pots in a steam-disinfested organic peat substrate (black peat, pH 6.5 to 6.8, N 110 to 190 mg/liter, P₂O₅ 140 to 230 mg/liter, K₂O 170 to 280 mg/liter) moistened to field capacity, and infested with wheat and hemp kernels colonized with isolate Py 1-14 of P. aphanidermatum at 1 g/liter. Five plants were transplanted into each of four pots filled with infested peat, while the same number of plants was grown in non-infested substrate as a control. Plants were kept in two growth chambers, each with 12 h of light per day at 20 or 30°C, and were irrigated daily to maintain the potting medium at field capacity. Symptoms first developed 5 days after the spinach was transplanted into infested potting medium in the growth chamber maintained at 30°C. After 10 days, all plants in this growth chamber were dead, while only 5% of the plants growing in infested potting medium in the 20°C growth chamber were affected. Control plants remained asymptomatic at both temperatures. P. aphanidermatum was re-isolated consistently from the symptomatic roots of plants grown in infested medium. No fungi were re-isolated from the asymptomatic control plants grown in non-infested substrate. To our knowledge, this is the first report of P. aphanidermatum causing root rot on S. oleracea in Italy. The same pathogen has been reported to cause root rot of spinach in other countries, including the United States (2). The disease is, at present, limited to the affected greenhouses observed in this study. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) M. L. Bates and M. E. Stanghellini. Plant Dis. 68:989, 1984. (3) H. Masago et al. Phytopathology 67:425, 1977. (4) T. Watanabe. Pictorial Atlas of Soil and Seed Fungi. CRC Press, FL., 2002.

PRE-PLANTING TREATMENTS WITH PHOSPHITE-BASED PRODUCTS AGAINST DIFFERENT FOLIAR AND SOIL-BORNE PATHOGENS OF VEGETABLE CROPS

Fifteen experimental trials were carried out under greenhouse conditions to evaluate the efficacy of preventative treatments based on phosphite salts on the following pathosystems: tomato/Phytophthora nicotianae, zucchini/P. capsici, lettuce/Fusarium oxysporum f.sp. Iactucae, rocket/Fusarium oxysporum f. sp. raphani, wild rocket/Plectosphaerella cucumerina and basii/Peronospora belbahrii. The possible use of phosphite salts in nursery cultivation systems is considered in comparison with chemical fungicides. Phosphites-based products reduced 66-88% and 56-72% the severity of Phytophthora crown root rot of tomato and zucchini, respectively. Four application with the phosphites-based products provided a disease reduction of Fusarium wilt of lettuce from of 33 to 83% and of 45 to 68% on cultivated rocket. These products provide the most constant results when applied in three treatments against Plectosphaerella cucumerina with a disease reduction ranging between 34%-82%. Phosphite-based products showed results statistically similar to mefenoxam when tested against downy mildew of basil. Their contribution to disease management can be very interesting, because they can complement other control measures.

EFFECT OF BIOSOLARISATION ON THE MICROBIAL POPULATIONS OF SUBSTRATES INFESTED WITH FUSARIUM OXYSPORUM BY PCR-DGGE

Biosolarisation consists of combining solarisation and organic matter application for controlling soilborne pathogens. The effects of this control strategy on the microbial community is almost unknown and needs to be investigated with molecular tools. The aim of the research was to investigate how biosolarisation can affect the structure of the microbial populations evaluated by a culture independent method using DGGE of PCR-amplified 18S-ITS genes-coding fragments from DNA extracted directly from infested substrate. Substrate samples were artificially infested with Fusarium oxysporum f. sp. conglutinans (FOC) and F. oxysporum f.sp. basilici (FOB) in order to evaluate the shift in fungal population by using culture independent methods. Solarisation was carried out with transparent polyethylene film during the summer period in a greenhouse located in Northern Italy, in combination or not with Brassica carinata defatted seed meals and/or compost. Biosolarisation treatment was carried out in a growth chamber by heating the substrate for 7 and 14 days at optimal (55-52 degrees C for 6 h, 50-48 degrees C for 8 h and 47-45 degrees C for 10 h/day) and sub-optimal (50-48 degrees C for 20 h, 45-43 degrees C for 8 h and 40-38 degrees C for 10 h/day) temperatures. Plate counts and polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) analyses were performed to evaluate the effect of biosolarisation on the microbial population. The abundance of FOC and FOB was reduced as a consequence of biosolarisation, while bacterial populations were higher compared to control samples during the experiment. PCR-DGGE fingerprints of the ascomycete community obtained from DNA directly extracted from infested substrate samples showed that the use of organic amendments increased the similarity of the fungal populations.

First Report of Root Rot Caused by Pythium aphanidermatum on Bell Pepper (Capsicum annuum L.) in Italy

During July 2012, symptoms of root rot were observed on bell pepper (Capsicum annuum) grown in 2,000 m² of commercial greenhouses near Cuneo in northern Italy. Symptoms first developed 30 to 40 days after transplanting, when greenhouse temperatures ranged from 25 to 30°C, and 10% of the plants were affected. Affected plants were stunted with leaf chlorosis, reduced growth, and sudden wilting. Roots were severely affected with a brown discoloration, water-soaking, and soft rot. Eventually, affected plants collapsed. Tissue fragments of 1 mm² were excised from symptomatic roots, dipped in a 1% sodium hypochlorite solution, and placed on potato dextrose agar (PDA) and an agar medium selective for oomycetes (3). Plates were incubated under constant fluorescent light at 22 ± 1°C for 5 days. An isolate grown for 12 days on V8 agar medium (200 ml V8 Campbell Soup, 15 g agar, 0.5 g CaCO₃, and 1 liter distilled water) showed aseptate hyphae that were 3.5 to 6.3 μm (avg. 5.2 μm) wide. Oogonia were globose, smooth, and 24.3 to 29.0 (avg. 25.1) μm in diameter. Antheridia were barrel-shaped, while oospores were globose, and 17.3 to 23.5 μm (avg. 21.2 μm) in diameter. These morphological characters identified the microorganism as a Pythium sp. (4). The ITS region of rDNA of a single isolate was amplified using the primers ITS1/ITS4 and sequenced. BLAST analysis (1) of the 781-bp segment (GenBank Accession KF840479) showed 100% homology with the ITS sequence of an isolate of Pythium aphanidermatum in GenBank (AY598622.2). Pathogenicity tests were performed twice on 30-day-old plants of C. annuum cv. Cuneo grown in 2-L pots (4 plants/pot), containing a steam-disinfested, organic peat substrate (70% black peat and 30% white peat, pH 5.5 to 6.0, N 110 to 190 mg/liter, P₂O₅ 140 to 230 mg/liter, K₂O 170 to 280 mg/liter) that was infested with wheat and hemp kernels colonized by the isolate of P. aphanidermatum, at a rate of 1 g colonized kernels/liter potting medium. The inoculum was prepared by autoclaving at 121°C for 30 min a mixture of wheat-hemp kernels (2:1 v/v) in a 1-liter flask, to which the bell pepper isolate of P. aphanidermatum was added in the form of colonized agar medium selective for oomycetes plugs. Before use, the inoculated flask was incubated for 10 days at 22°C in the dark. Four plants/pot were transplanted into each of four pots filled with the infested medium/growth chamber, while the same number of plants were grown in non-infested substrate in pots in each growth chamber. Plants were kept in two growth chambers, one set at 20°C and the other at 28°C. Symptoms first developed 7 days after inoculation. After 30 days, 50% of inoculated plants showed brown roots and died in the growth chamber set at 28°C, while only 10% of the plants were symptomatic at 20°C. Control plants remained asymptomatic at both temperatures. P. aphanidermatum was re-isolated consistently from the symptomatic roots of plants grown in the infested soil by using the same protocol as the original isolations, while no fungal colonies were obtained from asymptomatic roots of the non-inoculated control plants. To our knowledge, this is the first report of the presence of P. aphanidermatum on C. annuum in Italy. The same disease was reported in the United States (2). The importance of the disease, although limited in distribution at present to the greenhouses surveyed in northern Italy, could increase in areas where sweet pepper is grown intensively. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) D. O. Chellemi et al. Plant Dis. 84:1271, 2000. (3) H. Masago et al. Phytopathology 67:425, 1977. (4) T. Watanabe. Pictorial Atlas of Soil and Seed Fungi. CRC Press, Boca Raton, FL, 2002.

VARIETAL RESISTANCE TO CONTROL FUSARIUM WILTS OF LEAFY VEGETABLES UNDER GREENHOUSE

Fusarium wilts of leafy vegetables are difficult to manage under intensive cropping systems. The objective of this study was to evaluate, in three experimental trials, the susceptibility of commercial cultivars of lettuce, wild and cultivated rocket and lamb's lettuce to Fusarium wilts in orderto provide information to breeders, as well as to growers. Some of the cultivars of lettuce tested were completely resistant to the three races of Fusarium wilt. It is interesting to observe that most of the resistant cultivars were 'Batavia red'. Only few rocket cultivars commercially available show a partial resistant reaction to F. oxysporum f.sp. raphani, while, varietal resistance is not applicable at the moment to control Fusarium wilt of lamb's lettuce. The integration of cultural practices, use of resistant cultivars, when available, chemicals and biological control agents, permit to prevent and manage these important diseases on leafy vegetables for fresh-cut production.

CONTROL OF SOIL-BORNE DISEASES BY DIFFERENT COMPOSTS IN POTTED VEGETABLE CROPS

The composting process and the type and nature of wastes and raw materials influence the maturity, quality and suppressiveness of composts. Variability in disease suppression also depends on the pathosystem, on soil or substrate type, on chemical-physical conditions, like pH and moisture, and on the microbial component of compost. The aim of the research was to evaluate the suppressiveness of composts, originated from green wastes and/or municipal biowastes, and produced by different composting plants located in Europe. The composts were tested against soil-borne pathogens in greenhouse on potted plants: Fusarium oxysporum f.sp. busilici/basil, Pythium ultimum/cucumber, Rhizoctonia solani/bean. Composts were blended with a peat substrate at different dosages (10, 20 and 50% vol./vol.) 14 days before seeding or transplanting. Pythium ultimum and Rhizoctonia solani were mixed into the substrate at 0.5 g of wheat kernels L(-1) 7 days before seeding, while, in the case of Fusarium oxysporum f.sp. basilici, chlamydospores were applied at 1 x 10(4) CFU/g. Seeds of basil, cucumber and bean were sown into 2 L pots in greenhouse. The number of alive plants was counted and above ground biomass was weighed 30 days after seeding. The number of infected cucumber and basil plants was significantly reduced by increasing dosages of composts, but municipal compost was phytotoxic when applied at high dosages compared to green compost. Moreover, municipal compost increased the disease caused by Rhizoctonia solani on bean. The use of compost in substrates can be a suitable strategy for controlling soil-borne diseases on vegetable crops, but results depend on type of composts, application rates and pathosystems.

First Report of Southern Blight Caused by Sclerotium rolfsii on Common Bean (Phaseolus vulgaris) in Italy

Common bean (Phaseolus vulgaris L.) is grown worldwide for consumption of dry or green beans. During late spring of 2012, yellowing and wilting symptoms were observed in a commercial bean field cv. Lingua di fuoco in Cagliari Province (Sardinia, southern Italy) on 30% of plants 4 to 5 months after sowing. The first symptoms developed in May, when temperatures reached 18 to 30°C. Affected plants showed crown rot, necrosis of the cortex, and foliar chlorosis. As disease progressed, plants collapsed. In the presence of abundant moisture, white mycelium developed on the senescent tissue along with light to dark brown sclerotia (3.0 to 4.8 mm in diameter). Symptomatic tissue was disinfested for 1 min in 1% NaOCl and plated on potato dextrose agar (PDA) amended with 25 mg streptomycin sulfate/liter. The fungus that was isolated consistently from symptomatic plants onto PDA at 23°C grew rapidly in culture with silky-white, sterile mycelium, formed light to dark brown sclerotia (each 1.8 to 3.2 mm in diameter) after 7 days, and readily produced aerial hyphae. These morphological features are typical of Sclerotium rolfsii (2). The internal transcribed spacer (ITS) region of ribosomal DNA (rDNA) was amplified for one isolate using ITS1/ITS4 primers (4), and sequenced (GenBank Accession No. KF002510). BLASTn analysis (1) of the 656-bp segment showed 87% homology with the ITS sequence of an S. rolfsii isolate (JF819727). Pathogenicity of one isolate was confirmed by inoculating healthy P. vulgaris plants cv. Lingua di fuoco grown in 2-liter pots in a steamed potting mix containing 50% Tecno2 (70% white peat and 30% clay) and 50% Tiesse 3 (60% white peat, 20% clay, and 20% perlite) (Turco Silvestro terricci, Bastia d'Albenga, SV, Italy). Inoculum consisting of mycelium and sclerotia of the pathogen produced from 10-day-old cultures on PDA was mixed in the soil at 0.5 g/liter substrate. Four 7-day-old plants per pot, with three replicate pots, were used for inoculation. The same number of control plants grown in the same substrate were inoculated with non-colonized PDA as a negative control treatment. The pathogenicity test was repeated. Plants were kept in a growth chamber at 30°C and 85% RH. Inoculated plants developed symptoms of leaf yellowing within 10 days, followed by crown rot, appearance of white mycelium and sclerotia, and eventual wilting. Control plants remained asymptomatic. Isolations from inoculated plants demonstrated the absence of latent infections by the fungus S. rolfsii, but the fungus was not reisolated from non-inoculated control plants. To our knowledge, this is the first report of S. rolfsii infecting P. vulgaris in Italy. Southern blight has been reported on common bean in sub-tropical and tropical areas of the world (3), where it can cause severe crop losses. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) J. E. M. Mordue. CMI Descriptions of Pathogenic Fungi and Bacteria No. 410, 1974. (3) H. F. Schwartz et al. Page 20 in: Compendium of Bean Diseases. American Phytopathological Society Press, St. Paul, MN, 2005. (4) T. J. White et al. PCR Protocols. Page 315 in: A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990.

First Report of a New Leaf Spot Caused by Plectosphaerella cucumerina on Field Grown Endive (Cichorium endivia) in Italy

During summer 2012, symptoms of a new leaf spot disease were observed in several commercial fields in Treviglio (Bergamo, northern Italy) on plants of curly (Cichorium endivia var. crispum) and Bavarian (C. endivia var. latifolium) endive (Asteraceae). This crop is widely grown in the region for fresh market. The first symptoms on leaves of affected plants consisted of small (1 mm) black-brown spots of irregular shape, later coalescing into larger spots, up to 10 to 15 mm diameter. Eventually, spots were surrounded by a yellow halo. Particularly, affected tissues rotted quickly under high moisture. Disease severity was greatest at 75 to 90% RH and air temperature between 23 and 30°C, where affected tissues rotted quickly. This disease resulted in severe production losses. On one farm in particular, three different fields totaling 2 ha, 5 to 13% of the plants were affected. Diseased tissue was excised, immersed in a solution containing 1% sodium hypochlorite for 60 s, rinsed in water, then placed on potato dextrose agar (PDA) medium, containing 25 mg/liter of streptomycin sulphate. After 5 days, a fungus developed producing a whitish-orange mycelium when incubated under 12 h/day of fluorescent light at 23°C. The isolates obtained were purified on PDA. On this medium, they produced hyaline elliptical and ovoid conidia, rarely septate, measuring 5.0 to 9.0 × 1.7 to 3.9 (average 6.0 × 2.9) μm. Conidia were born on phialides, single, clavate, and 2.8 × 1.4 μm. Such characteristics are typical of Plectosphaerella sp. (1,2). The internal transcribed spacer (ITS) region of rDNA was amplified using the primers ITS1/ITS4 (3) and sequenced. BLAST analysis of the 530-bp segment obtained from C. endivia var. crispum isolate PLC28 and of the 527-bp from C. endivia var. latifolium isolate PLC 30, respectively, showed 99% similarity with the sequence of Plectosphaerella cucumerina (anamorph Plectosporium tabacinum), GenBank EU5945566. The nucleotide sequences of isolates PLC 28 and PLC 30 have been assigned the GenBank accession numbers KC293994 and KC293993, respectively. To confirm pathogenicity, tests were conducted on 30-day-old C. endivia plants. C. endivia var. crispum cv Myrna and C. endivia var. latifolium cv. Sardana plants, grown in 2-liter pots (1 plant per pot, 10 plants per treatment) were inoculated by spraying a 10⁶ CFU/ml conidial suspension of the two isolates of P. cucumerina, prepared from 10-day-old cultures, grown on PDA. Inoculated plants were maintained in a growth chamber at 25 ± 1°C and 90% RH for 5 days. Non-inoculated plants, only sprayed with water, served as controls. All plants inoculated with the two isolates, showed typical leaf spots 7 days after the artificial inoculation, similar to those observed in the field. Later, spots enlarged and leaves rotted. Non-inoculated plants remained healthy. P. cucumerina was reisolated from inoculated plants. The pathogenicity tests were conducted twice with identical results. This is, to our knowledge, the first report of P. cucumerina on endive n Italy, as well as worldwide. Due to the importance of the crop in Italy, this disease can cause serious economic losses. References: (1) A. Carlucci et al. Persoonia 28:34, 2012. (2) M. E. Palm et al. Mycologia 87:397, 1995. (3) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, 1990.

First Report of Damping-off Caused by Pythium aphanidermatum on Leaf Beet (Beta vulgaris subsp. vulgaris) in Italy

During July 2010, symptoms of crown and root rot were observed on leaf beet (Beta vulgaris L. subsp. vulgaris) grown in a commercial field near Torino (northern Italy). The first symptoms developed 25 days after sowing with temperatures ranging from 25 to 30°C, and 20% of plants were affected. Affected plants were stunted and leaves showed chlorosis and suddenly wilted. The collar and young stems were affected first and appeared brown, water-soaked, and were characterized by a soft rot. Eventually, all affected plants collapsed. Thin aerial mycelia were visible on the surface of the infected plants if maintained at a high relative humidity. Tissue fragments of 1 mm² were excised from the margins of the lesions, dipped in a solution containing 1% sodium hypochlorite, and plated on potato dextrose agar (PDA) and on a medium selective for oomycetes (2). Plates were incubated under constant fluorescent light at 22 ± 1°C for 5 days. Five isolates, grown on V8 medium (vegetable mix 300 g; agar 15 g; CaCO₃ 1.5 g; distilled water 1 liter) and observed under light microscope showed the morphological characters of Pythium aphanidermatum (3). This result was confirmed by PCR and sequence analysis. The internal transcribed spacer (ITS) region of rDNA of a single isolate (Py 7/10) was amplified using the primers ITS1/ITS4 and sequenced. BLAST analysis (1) of the 815 bp segment showed a 99% homology with the sequence of P. aphanidermatum (GenBank Accession JN695786). The nucleotide sequence has been assigned to the GenBank Accession JX462954. Pathogenicity tests were performed twice on B. vulgaris subsp. vulgaris grown in 2-liter pots, containing a steam disinfested organic peat substrate (70% black peat, 30% white peat, pH 5.5 to 6, N 110 to 190 mg L^-1, P₂O₅ 140 to 230 mg L^-1, K₂O 170 to 280 mg L^-1), infested with wheat and hemp kernels colonized with a strain of P. aphanidermatum at a rate of 1 g L^-1. Ten seeds per pot were sown in four pots filled with the infested medium, while the same number of seeds were sown in non-infested substrate. Plants were kept in two growth chambers, at 20 and 27°C. The first symptoms developed 7 days after the artificial inoculation. After 20 days, 70% of plants were infected at 27°C, while 10% were affected at 20°C. Control plants remained healthy at both temperatures. P. aphanidermatum was consistently reisolated from the lesions. To our knowledge, this is the first report of damping off of B. vulgaris subsp. vulgaris caused by P. aphanidermatum in Italy. The importance of the disease, at present limited, could increase in areas where leaf beet is intensively grown. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) H. Masago et al. Phytopathology 67:425, 1977. (3) T. Watanabe. Pictorial Atlas of Soil and Seed Fungi. CRC Press, Florida, 2002.

Effect of silicates and electrical conductivity on Fusarium wilt of hydroponically grown lettuce

Silicon can stimulate natural defense mechanisms in plants, reducing foliar diseases like powdery arid downy mildew on several crops, including lettuce. The effect of silicate on Fusarium wilt, caused by Fusarium oxysporum f. sp. lactucae was evaluated under greenhouse conditions on lettuce grown in soilless systems. Silicon, as potassium silicate, was added at 100 mg L(-1) of nutrient solution at three levels of electrical conductivity; 1.5-1.6 mS cm(-1) (E.C.1), 3.0-3.2 mS cm(-1) (E.C.2) and 4-4.2 mS cm(-1) (E.C.3). Pots containing lettuce plants were first inoculated with F. oxysporum f. sp. lactucae (3x10(5) chlamidospores ml(-1)) 15-20 days before transplanting. Disease severity and physiological parameters, including chlorophyll content, were analyzed weekly after transplanting. The addition of potassium silicate slightly reduced Fusarium wilt, at all levels of electrical conductivity under study, compared to the control. On the contrary, the increase of electrical conductivity of the nutrient solution showed no effect on the disease. The use of silicon was previously demonstrated to significantly reduce downy mildew on lettuce in soilless systems, and in this trial it demonstrated to slightly reduce disease severity of an important soil-borne pathogen like F. oxysporum f. sp. lactucae, suggesting the possibility to apply it successfully in soilless crops.

Production and release of asexual sporangia in Plasmopara viticola

To study the influence of environmental conditions on sporulation of Plasmopara viticola lesions under vineyard's conditions, unsprayed vines were inspected every second or third day and the numbers of sporulating and nonsporulating lesions were counted in two North Italy vineyards in 2008 to 2010. Infected leaves were removed so that only fresh lesions were assessed at each field assessment. Sporulation was studied at two scales, across field assessments and across the seasonal population of lesions. Frequencies of sporulating lesions were positively correlated with the numbers of moist hours in the preceding dark period (i.e., the number of hours between 8:00 p.m. and 7:00 a.m. with relative humidity ≥80%, rainfall >0 mm, or wetness duration >30 min). In a receiver operating characteristic analysis, predicted sporulation based on the occurrence of ≥3 moist hours at night provided overall accuracy of 0.85. To study the time course of sporulation on lesions which were not washed by rainfall, numbers of sporangia produced per square millimeter of lesion were estimated on individual cohorts of lesions over the whole infectious period. The numbers of sporangia per square millimeter of lesion increased rapidly during the first 4 days after the beginning of sporulation and then tapered off prior to a halt; the time course of cumulative sporangia production by a lesion followed a monomolecular growth model (R(2) = 0.97). The total number of sporangia produced by a square millimeter of lesion increased as the maximum temperature decreased and moist hours in the dark increased. To study the release pattern of the sporangia, spore samplers were placed near grapevines with sporulating lesions. Airborne sporangia were caught in 91.2% of the days over a wide range of weather conditions, including rainless periods. The results of this study provide quantitative information on production of P. viticola sporangia that may help refine epidemiological models used as decision aids in grape disease management programs.

Phytophthora capsici: A Soilborne Pathogen Dangerous on Grafted Tomato (Solanum lycopersicum × S. hirsutum) in Italy

During an extensive survey carried out in Piedmont (northern Italy) aimed at identifying the emerging soilborne diseases affecting tomato in commercial fields where alternatives to methyl bromide have been implemented in response to national and international regulations, sudden collapse of tomato plants, cv. Tomahawk, grafted on cv. Beaufort, were repeatedly observed in a commercial plastic tunnel operation. Affected plants suddenly collapsed 60 days after transplant during the month of May 2010. Symptoms included chlorosis, stunting, and severe root and crown rot, leading to sudden collapse of approximately 25% of the plants within 60 days of transplant. Symptomatic tissues from the root and collar of infected plants were surface disinfested for 1 min in a 1% NaOCl solution, rinsed for 5 min in water, and submerged in selective medium based on corn meal agar. A Phytophthora-like organism (2) with characteristic coenocytic hyphae was consistently isolated and transferred to V8 agar. The sporangia were spherical to ovoid, papillate, and 40 to 77 × 23 to 34 (average 55.1 × 30.3) μm. Oospores were globose and 22.2 to 30.8 μm. The internal transcribed spacer (ITS) region of rDNA of a single isolate was amplified using the primers ITS1/ITS4 and sequenced. BLAST analysis (1) of the 750-bp segment showed a 100% homology with the sequence of Phytophthora capsici JN382543.1. The nucleotide sequence has been assigned the GenBank Accession No. JX090306. Pathogenicity tests were performed on healthy 30-day-old tomato plants cv. Beaufort by using one strain of P. capsici grown for 15 days at 22 to 25°C on a mixture of 2:1 wheat/hemp kernels, and then 1 g per L of the inoculum was mixed into a substrate based on peat blonde/peat black (15:85 v/v). Two plants were transplanted into 3-L pots, with five replicates. Ten non-inoculated plants represented the control treatment; the trial was repeated once. All plants were kept in a greenhouse at temperatures ranging from 22 to 25°C. Inoculated plants became chlorotic 7 days after inoculation and root and crown rot developed 30 days after inoculation. Control plants remained symptomless. P. capsici consistently was reisolated from inoculated plants. In Italy, the presence of P. nicotianae on hybrids of Solanum lycopersicum × S. hirsutum is known (3), while, to the best of our knowledge, this is the first report of P. capsici on the hybrid S. lycopersicum × S. hirsutum in Italy. The economic importance of the disease can increase due to the expanding use of grafted tomato plants. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997 (2) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. APS Press, St Paul, MN, 1996. (3) A. Garibaldi and M. L. Gullino. Acta Hortic. 833:35, 2010. (4) H. M. Masago et al. Phytopathology 67:425, 1977.

First Report of Plectosphaerella cucumerina on Greenhouse Cultured Wild Rocket (Diplotaxis tenuifolia) in Italy

During spring 2012, symptoms of an unusual leaf spot disease were observed in several commercial greenhouses near Salerno (southern Italy) on plants of Diplotaxis tenuifolia (cv Selvatica). The first symptoms on leaves of affected plants consisted of small (1 mm) black-brown spots of irregular shape, later coalescing into larger spots, 1 cm in diameter. Spots were surrounded by a yellow halo, and were mostly located on the foliar limb, rib, and petiole. Affected leaves were often distorted, appearing hook-like. The disease was severe under 75 to 90% RH, at air temperature of 20 to 26°C, and caused severe production losses on about 50 ha. Particularly, affected tissues rotted quickly after packaging and during transit and commercialization of processed rocket. Diseased tissue was excised, immersed in a solution containing 1% sodium hypochlorite for 60 s, rinsed in water, then placed on potato dextrose agar (PDA) medium, containing 25 mg/l of streptomycin sulphate. After 5 days, a fungus developed producing a whitish-orange mycelium when incubated under 12 h/day of fluorescent light at 22°C. The isolates obtained were purified on PDA. On this medium, they produced hyaline elliptical and ovoid conidia, sometimes one-septate, measuring 4.5 to 9.2 × 1.7 to 3.5 (average 6.8 × 2.6) μm. Conidia were born on phialides, measuring 6.8 to 20.2 × 1.3 to 3.1 (average 16.5 × 2.1) μm. Such characteristics are typical of Plectosphaerella sp. (2). The internal transcribed spacer (ITS) region of rDNA was amplified using the primers ITS1/ITS4 (3) and sequenced. BLAST analysis of the 519-bp segment showed a 98% similarity with the sequence of Plectosphaerella cucumerina (GenBank Accession No. AB469880). The nucleotide sequence has been assigned the GenBank Accession JX185769. To confirm pathogenicity, tests were conducted on 45-day-old D. tenuifolia plants. Plants (21/treatment), grown in 15 liter pots (7 plants/pot) were inoculated by spraying a 1 × 10⁶ CFU/ml conidial suspension of one isolate of P. cucumerina, prepared from 10-day-old cultures, grown on PDA. Inoculated plants were maintained in a growth chamber at 23 ± 1°C, at 90% RH for 4 days. Non-inoculated plants served as control. Inoculated plants showed the typical first leaf spots 6 days after the artificial inoculation. Four days later, spots enlarged and leaves became distorted, showing chlorosis. Non-inoculated plants remained healthy. P. cucumerina was reisolated from inoculated plants. The pathogenicity test was conducted twice with identical results. This is, to our knowledge, the first report of P. cucumerina on D. tenuifolia in Italy as well as worldwide. P. cucumerina has been described as associated with root and collar rots of other horticultural crops in southern Italy (1). Due to the importance of the crop in Italy, this disease can cause serious economic losses. References: (1) A. Carlucci et al., Persoonia, 28:34, 2012. (2) M. E. Palm et al. Mycologia, 87:397, 1995. (3) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, 1990.

First Report of Leaf Spot of Lettuce (Lactuca sativa L.) Caused by Phoma tropica in Italy

Lettuce (Lactuca sativa L.) is widely grown in Italy, with the production for the preparation of ready-to-eat salads becoming increasingly important. During the spring of 2011, a previously unknown leaf spot was observed on L. sativa plants, cv Rubia, grown in several plastic tunnels in Lumbardy (northern Italy), 20 to 25 days after sowing. Thirty to forty per cent of leaves of the plants growing in the part of the tunnel with the highest relative humidity were affected. Leaves of infected plants showed extensive, irregular, dark brown, necrotic lesions with a chlorotic halo. Lesions initially ranged from 0.5 to 3 mm, then eventually coalesced, reaching 2 to 3 cm, showing a well-defined, dark brown border. Affected leaves senesced and withered. The crown was not affected by the disease. Diseased tissue was excised, immersed in a solution containing 1% sodium hypochlorite for 60 s, rinsed in water, then cultured on potato dextrose agar (PDA), amended with 25 mg/l of streptomycin sulphate. After 5 days, a fungus developed, producing a greenish grey mycelium with a white border when incubated under 12 h/day of fluorescent light at 21 to 23°C. In order to favor the production of conidia, the fungus was transferred on malt extract agar (MA) and maintained under 12 h/day of fluorescent light at 22°C. After 15 days, black pycnidia, 175 to 225 μm, developed, with hyaline, elliptical, unicellular conidia, measuring 3.21 to 6.7 × 1.08 to 3.2 (average 5.5 × 1.9) μm. On the basis of these morphological characteristics, the fungal causal agent of the disease could be related to the genus Phoma (2). The internal transcribed spacer (ITS) region of rDNA of the isolate PHT30 was amplified using the primers ITS1/ITS4 and sequenced. BLAST analysis (1) of the 466-bp segment showed a 99% similarity with the sequence of Phoma tropica (GenBank Accession No. JF923820.1). The nucleotide sequence has been assigned the GenBank Accession No. JQ954396. Pathogenicity tests were performed by spraying healthy 20-day-old lettuce plants, cv Rubia, with a spore suspension (1 × 10⁵ conidia/ml) prepared from 14-day-old colonies of the strain PHT30 grown on MA cultures. Plants inoculated with water alone served as controls. Ten plants per isolate were used. Plants were covered with plastic bags for 5 days after inoculation and maintained in a growth chamber at 20°C and 80% relative humidity. The first foliar lesions, similar to those occurring on the naturally infected plants, developed on leaves 12 days after inoculation. Control plants remained healthy. The pathogen was consistently reisolated from leaf lesions. The pathogenicity test was completed twice. To our knowledge, this is the first report of the presence of P. tropica on lettuce in Italy as well as worldwide. In the United States, the presence of P. exigua was reported in 2006 (3). The economic importance of the disease at present is limited, probably also because symptoms can be confused with those caused by Botrytis cinerea. However, P. tropica could become a more significant problem because of the importance of the crop. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) G. H. Boerema. Trans. Br. Mycol. Soc. 67:289, 1976. (3) S. Y. Koike. Plant Dis. 90:1268, 2006.

First Report of Rust Caused by Pucciniastrum circaeae on Fuchsia × hybrida in Italy

Fuchsia is a genus of flowering plants that is native to South America and New Zealand and belongs to the family Onagraceae. In September 2011, 2-year-old potted plants of Fuchsia × hybrida, cv. Citation, in a garden located near Biella (northern Italy) showed signs and symptoms of a previously unknown disease. Typically, infected plants showed leaf chlorosis followed by the appearance of necrosis on the adaxial leaf surfaces, while the abaxial surfaces showed orange uredinia irregularly distributed. As the disease progressed, infected leaves turned yellow and wilted. Affected plants showed a progressive phylloptosis and also flowering was negatively affected. Urediniospores were globose, yellow to orange, and measured 14.6 to 25.9 (average 19.6) μm. Teliospores were not observed. Morphological characteristics of the fungus corresponded to those of the genus Pucciniastrum. DNA extraction and PCR amplification were carried out with Terra PCR Direct Polymerase Mix (Clontech, Saint Germain-en-Laye, France) and primers ITS1/ITS4 (4). A 700-bp PCR product was sequenced and a BLASTn search (1) confirmed that the sequence corresponded with a 96% identity to Pucciniastrum circaeae. The nucleotide sequence has been assigned the GenBank Accession No. JQ029688. Pathogenicity tests were performed by spraying leaves of healthy 1-year-old potted Fuchsia × hybrida plants with an aqueous suspension of 1 × 10³ urediniospores ml^-1. The inoculum was obtained from infected leaves. Plants sprayed only with water served as controls. Three plants were used for each treatment. Plants were covered with plastic bags for 4 days after inoculation and maintained outdoors at temperatures ranging between 18 and 25°C. Lesions developed on leaves 20 days after inoculation with the urediniospore suspension, showing the same symptoms as the original plants, whereas control plants remained healthy. The organism that was recovered from the lesions after inoculation was the same as the one obtained from the diseased plants. The pathogenicity test was carried out twice with similar results. The presence of P. fuchsiae, later identified as P. epilobii, was repeatedly reported in the United States (3). P. epilobii and P. circaeae have closely related hosts and morphologically similar urediniospores. These species were reported to form a single group in molecular phylogenetic trees (2). This is, to our knowledge, the first report of P. circaeae on Fuchsia × hybrida in Italy. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997 (2) Y. M. Liang et al. Mycoscience 47:137, 2006. (3) L. B. Loring and L. F. Roth. Plant Dis. Rep. 48:99, 1964. (4) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, 1990.

First Report of Leaf Spot of Wild (Diplotaxis tenuifolia) and Cultivated (Eruca vesicaria) Rocket Caused by Alternaria japonica in Italy

Wild (Diplotaxis tenuifolia) and cultivated (Eruca vesicaria) rocket, popular crops in Italy as well as in many Mediterranean areas, are grown for fresh consumption as well as for dish decoration. During fall and winter of 2010 to 2011, extensive necroses were observed on leaves of D. tenuifolia and E. vesicaria that were grown in commercial greenhouses in Piedmont and Liguria (northern Italy). The disease affected 30 to 40% of 60-day-old plants. First symptoms were usually black-brown lesions, 1 to 30 mm in diameter, which progressively turned black. Lesions usually started on the upper side of older leaves at the leaf margins and tips and developed a yellow halo. Eventually, lesions also affected leaf veins and stems. A fungus was consistently isolated from infected leaves on potato dextrose agar and was grown on water agar (15 g/liter) amended with autoclaved rocket tissues (100 g/liter). After 12 days of growth at 22°C and 12-h dark/12-h light, conidia that were produced were dark brown, obclavate, obpyriform, ovoid or ellipsoid, with beaks. Round conidia without beaks were also present. Conidia showed two to seven (average three to four) transverse and one to three longitudinal septa, and measured 17.7 to 56.2 (average 30.9) × 6.6 to 17.8 (average 10.8) μm. Conidia were produced singly or in short chains (two to three elements) and mostly presented a conical or cylindrical beak, 1.8 to 7.3 (average 3.6) μm, pale light brown to brown. On the basis of its morphological characteristics, the pathogen was identified as an Alternaria sp. (3). DNA was extracted with Terra PCR Direct Polymerase Mix (Clontech, Mountain View, CA) and PCR was carried out with ITS 1/ ITS 4 primer (4). A 553-bp PCR product was sequenced and a BLASTn search (1) confirmed that the sequence corresponded to Alternaria japonica. The nucleotide sequence has been assigned the GenBank Accession No. JP 742643. Pathogenicity tests were performed by spraying leaves of healthy 30-day-old wild and cultivated rocket plants with an aqueous 1 × 10⁵ spore/ml suspension. The inoculum was obtained from cultures of the fungus grown on sterilized host leaves placed on water agar for 20 days in light/dark at 22 ± 1°C. Plants sprayed only with water served as controls. Three pots (four plants per pot) were used for each treatment. Plants were covered with plastic bags for 4 days after inoculation and maintained in a glasshouse at 22 ± 1°C. Lesions developed on leaves 7 days after inoculation with the spore suspension, whereas control plants remained healthy. A. japonica was consistently reisolated from these lesions. The pathogenicity test was carried out twice. The presence of A. japonica has been reported on several brassica hosts, such as Brassica napus, B. nigra, B. oleracea, and B. rapa (2). This is, to our knowledge, the first report of A. japonica on wild and cultivated rocket in Italy as well as in Europe. Because of the importance of rocket in many countries, the potential impact of this disease is high. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997 (2) J. C. David, IMI Description of Fungi and Bacteria. 144:1432, 2000. (3) E. G. Simmons. Alternaria. An Identification Manual. CBS Biodiversity Series 6, Utrecht, The Netherlands, 2007. (4) T. J. White et al. In: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, 1990.

First Report of Leaf Spot of Rocket (Eruca sativa) Caused by Fusarium equiseti in Italy

During the summer of 2010, rocket (Eruca sativa) plants grown in an open field and under a plastic tunnel in Piedmont (northern Italy) showed symptoms of a previously reported foliar disease. Symptoms were observed on 30-day-old plants and consisted of small, circular, brown leaf spots (1 to 3 to 10 to 12 mm in diameter), sometimes later becoming elliptical. Necrotic lesions were cracked in the center and showed a well-defined border, frequently surrounded by a violet-brown halo. Approximately 40% of the plants were affected with 30 to 40% of the leaves infected. An orange-brown colony with characteristics of Fusarium was isolated from leaf tissues of 30 infected plants on potato dextrose agar (PDA). Isolates were purified, subcultured on PDA, and single-spore cultures were obtained. On PDA, they produced orange-brown colonies and purple pigments. On Spezieller Nährstoffarmer agar (SNA) (1), the isolates produced hyaline macroconidia with dorsiventral curvature, five to seven septate, and measuring 36.2 to 49.3 × 3.4 to 5.3 (average 41.9 × 4.0) μm. Chlamydospores, solitary but also in short chains (two to three elements), measuring 7.2 to 15.3 (average 10.1) μm were produced on carnation leaf agar (CLA) after 10 days and became verrucose 20 days later. Macroconidia were produced on CLA in orange sporodochia from monophialides on branched conidiophores. Microconidia were not observed. Such characteristics are typical of the genus Fusarium (1). The rDNA ITS region (internal transcribed spacer) was amplified using the primers ITS1/ITS4 (2) and sequenced. BLASTn analysis of the 480-bp product obtained showed an E-value of 0.0 with Fusarium equiseti. The nucleotide sequence has been assigned the GenBank Accession No. JF460797. The translation elongation factor-1α (EF-1α) gene (GenBank Accession No. JN127347) was amplified using primers EF-1/EF-2 and sequenced. The 702-bp fragment showed 99% identity with F. equiseti (GenBank Accession No. FJ939673.1). To confirm pathogenicity, 20-day-old rocket plants were transplanted into 2-liter volume pots, filled with a steamed peat/perlite/sand (60:20:20 vol/vol) substrate and maintained in a growth chamber at 25 ± 1°C. Five pots per treatment were used, each pot containing two plants. The artificial inoculation was carried out either by spraying leaves with a spore suspension prepared from 15-day-old cultures of the pathogen on PDA or by applying CLA agar disks (6 mm in diameter) from 10-day-old cultures onto leaves. Control plants were inoculated with distilled water or with noninoculated agar disks. Plants were covered with plastic bags for 5 days. The first symptoms, consisting of chlorotic leaf halo and leaf spots surrounded by a violet-brown halo, developed 15 days after inoculation by foliar spraying and 5 days after inoculation by disks. Noninoculated plants remained healthy. F. equiseti was consistently isolated from symptomatic plants. The pathogenicity test was conducted twice. To our knowledge, this is the first report of F. equiseti on E. sativa in Italy. Currently, this disease is present in several farms in northern Italy. Its importance might increase because of the widespread cultivation of cultivated rocket in Italy. References: (1) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell, Ames, IA, 2006. (2) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, 1990.

First Report of Fusarium Wilt of Chicory (Cichorium intybus) Caused by Fusarium oxysporum in Italy

In the summer of 2009, a wilt of chicory was observed on 25 to 30% of 30-day-old Cichorium intybus L. cv. Clio plants grown outdoors on a commercial farm in Piedmont (northern Italy). Affected plants were chlorotic and stunted with poorly developed root systems compared with healthy plants. Black streaks were observed in the stem and proximal part of the leaf vascular system in wilted plants. Fusarium oxysporum Schltdl. was isolated from symptomatic vascular tissue on a Fusarium-selective medium (1) from 80% of samples. Grown on potato dextrose agar (PDA) for 4 days at 23°C, the colonies, initially white and later pale pink, produced hyaline microconidia that were oval-elliptical and cylindrical in shape measuring 5.6 to 14.9 (average 10.2) × 2.1 to 4.5 (3.0) μm, borne on short monophialides measuring 8.2 to 16.1 (average 13.2) × 2.1 to 4.2 (3.3) μm. Macroconidia were slightly curved, three-septate, with a slightly hooked apical cell and a foot-shaped basal cell measuring 24.9 to 41.6 (average 32.2) × 3.2 to 5.2 (4.3) μm. Chlamydospores were both terminally and intercalary, solitary but also in short chains (2 to 4 elements) measuring 21.1 to 41.0 (average 27.2) μm (2). The internal transcribed spacer (ITS) rDNA region was amplified using the primers ITS1/ITS4 and sequenced. BLASTn analysis of the 527-bp amplicon (GenBank Accession No. HQ644423) obtained had 98% sequence identity with F. oxysporum (GenBank Accession No. FJ605247). The translation elongation factor-1α (EF-1α) gene was amplified using primers EF-1/EF-2 and sequenced (GenBank Accession No. GU564259). The 663-bp fragment had 99% sequence identity with F. oxysporum (GenBank Accession Nos. EU313540, EU313539, and DQ837696). Pathogenicity tests were conducted on 15-day-old chicory plants from two cultivars (Clio and Katia). Thirty-five plants per cultivar were inoculated by dipping their roots in a 1 × 10⁶ CFU/ml suspension of isolate FusCic45B recovered from wilted chicory. Inoculated and noninoculated plants were transplanted into five pots filled with 10 liters of steamed mix (peat/perlite/sand, 60:20:20 vol/vol) and were maintained in a glasshouse at 25 to 27°C. Wilt symptoms and vascular discoloration of the roots, crown, and veins developed 15 days after inoculation on all inoculated plants. Plants of cv. Clio were more susceptible. F. oxysporum was always reisolated from infected plants using the Fusarium-selective medium. All noninoculated plants remained healthy. The pathogenicity test was conducted twice. To our knowledge, this is the first report of wilt caused by F. oxysporum on chicory, C. intybus, in Italy as well as worldwide. References: (1) H. Komada. Rev. Plant Prot. Res. 8:114, 1975. (2) E. Nelson et al. Fusarium Species: An Illustrated Manual for Identification. The Pennsylvania State University Press, University Park, 1983.

First Report of Collar and Root Rot Caused by Phytophthora tentaculata on Witloof Chicory (Cichorium intybus) in Italy

Witloof chicory (Cichorium intybus L.) is an important crop in Italy where most of the crop is still produced in soil. In September 2009, chicory plants (cv. Pan di Zucchero) grown on a commercial farm in Tarquinia (central Italy) showed symptoms of a previously unknown disease. Symptoms, observed 20 days after transplanting, consisted of stunting, yellowing of leaves, and a crown and root rot. Affected plants turned brown, wilted, and eventually died. At the soil level, dark brown-to-black water-soaked lesions coalesced and often girdled the stem. All of the crown and root system was affected. At this location, the disease was severe and widespread, with 60% of observed plants being affected. A Phytophthora-like organism was consistently isolated on a medium selective for oomycetes (4) after disinfestation of lower stem and root pieces of C. intybus for 1 min in a solution containing 1% NaOCl. Tissue fragments of 1 mm² were excised from the margins of the root and crown lesions. The pathogen genus was identified as Phytophthora based on morphological and physiological features. Sporangia were produced for identification by growing a pure culture for 15 days on modified V8 juice agar medium (Campbell V8 juice [200 ml], agar [15 g], CaCo₃ [0.5 g], and sterile water [800 ml]) under alternating light and dark (12/12 h). Sporangia were pyriform to ovoid, papillate, and measured 33.3 to 59.2 × 18.9 to 30.2 μm (average 39.9 × 25.8 μm). Chlamydospores developed in 28-day-old cultures and measured 21.3 to 30.2 × 19.5 to 29.7 μm (average 24.4 × 23.6 μm). Oogonia were globose and measured 26 to 41 μm (average 32.5 μm). Eighty percent of antheridia were paragynous. Amphyginous antheridia (15 to 20%) were also observed. Oospores were scarcely produced and measured 24 to 32 μm in diameter. The internal transcribed spacer (ITS) region of rDNA of a single isolate was amplified using the primers ITS4/ITS6 and sequenced. BLAST analysis (1) of the 851-bp segment showed 100% homology with the sequence of Phytophthora tentaculata. The nucleotide sequence has been assigned GenBank Accession No. GU949536. Pathogenicity of this isolate was confirmed by inoculating C. intybus cv. Pan di Zucchero plants 20 days after transplant. The same isolate was grown for 15 days on a mixture of 70:30 wheat/hemp kernels and then 5 g/liter of the inoculum was mixed into a substrate containing a mixture of blond and black peat (15:85 vol/vol), pH 5.5. Five plants per 2-liter pot were transplanted and four replicates were carried out. Twenty noninoculated plants represented the control treatment. The trial was repeated. Plants were kept in two growth chambers at two temperatures (20 and 25°C). Symptoms similar to those observed in the field developed 7 days after inoculation. Twenty days later, 100 and 40% of the plants were dead at 25 and 20°C, respectively. Control plants remained symptomless. P. tentaculata was consistently reisolated from symptomatic plants. To our knowledge, this is the first report of P. tentaculata on C. intybus in the world ( http://nt.ars-grin.gov/fungaldatabases/index.cfm ). P. tentaculata was recently reported on lavender in Spain (2) and oregano in Italy (3). The economic importance of this disease is relatively low on most commercial farms. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) L. Alvarez et al. Plant Dis. 90:523, 2006. (3) P. Martini et al. Plant Dis. 93:843, 2009. (4) H. Masago et al. Phytopathology 67:425, 1977.

First Report of Collar and Root Rot Caused by Pythium ultimum on Coriander in Italy

Coriander, Coriandrum sativum L., is an annual herb in the family Apiaceae. This plant, native to southern Europe, northern Africa, and southeastern Asia, is used in cooking as well as for medicinal uses. The leaves are commonly referred to as cilantro. In October 2009, severe outbreaks of a previously unknown root rot were observed in a commercial field located in the Alessandria Province (northern Italy) on 20-day-old plants belonging to cv. Comune. Five percent of plants were affected, showing stunting and extensive chlorosis starting on external leaves that eventually wilted. Root systems and collars of diseased plants appeared rotted. In advanced stages, young leaves were affected and the plants eventually collapsed and tissues dried out. Tissue fragments of 1 mm² were excised from the roots of infected plants, dipped in a solution containing 1% sodium hypochlorite, and plated on potato dextrose agar (PDA) and a medium selective for Oomycetes (3). Plates were incubated under constant fluorescent light at 22 ± 1°C for 4 to 5 days. One isolate, grown on V8 medium (vegetable mix, 300 g; agar, 15 g; CaCO₃, 1.5g; and distilled water, 1 liter), and observed under a light microscope showed hyphae generally aseptate, ranging from 1.3 to 6.24 μm in diameter, and produced sporangia consisting of complexes of swollen hyphal branches. Oogonia were globose, smooth, and 20.3 to 33.4 (average 25.4) μm in diameter. Antheridia were monoclinous, extending from immediately below oogonium, and measured 10.8 to 17.8 × 7.6 to 12.7 (average 14.4 × 10.4) μm. Oospores were single, globose, aplerotic and thick walled, and 15.8 to 24.2 (average 17.8) μm in diameter. These morphological characters were used to identify the microorganism as a Pythium sp. (3). The internal transcribed spacer (ITS) region of rDNA of a single isolate was amplified using the primers ITS1/ITS4 (2,4) and sequenced. BLAST analysis (1) of the 874-bp segment showed a 100% homology with the sequence of Pythium ultimum. The nucleotide sequence has been assigned the GenBank Accession No. GU478314. Pathogenicity tests were performed twice on coriander cv. Comune. Plants were grown in 2-liter pots containing a Brill Type 5 substrate (Brill Substrate GmbH & Co. KG, Niedersachsen, Germany) consisting of 15% blond peat, 85% black peat, pH 5.5 to 6, and pasteurized at 80°C for 30 min. The potting mix was infested at a rate of 5 g/liter with wheat and hemp kernels colonized with one strain of P. ultimum. Ten plants (1 plant per pot) were grown in the infested substrate and 10 plants were grown in noninfested substrate. Plants were kept in a growth chamber at 20°C. The first symptoms, consisting of reduced growth and chlorosis, developed within 7 days, while control plants remained healthy. P. ultimum was consistently isolated from the roots. To our knowledge, this is the first report of P. ultimum causing disease of coriander in Italy as well as worldwide. At this time, the economic importance of Pythium rot on coriander in Italy remains unknown. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) W. Chen et al. Exp. Mycol.16:22, 1992. (3) T. Watanabe. Pictorial Atlas of Soil and Seed Fungi. CRC Press, Boca Raton, FL, 2002. (4) T. J. White et al. Page 38 in: PCR protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, 1990.

First Report of Leaf Blight on Woodland Sage Caused by Rhizoctonia solani AG 1 in Italy

Woodland sage (Salvia nemorosa L.; Lamiaceae) is a hardy herbaceous perennial plant that is easy to grow and propagate and is used in parks and grown as potted plants. During the summer of 2009 in a nursery near Torino in northern Italy, a leaf blight was observed on 30-day-old plants of cv. Blau Koenigin grown in pots under shade. Semicircular, water-soaked lesions developed on leaves just above the soil line at the leaf-petiole junction and later along leaf margins. Lesions expanded along the midvein until the entire leaf was destroyed. Blighted leaves turned brown, withered, and clung to the shoots. No symptoms were observed on the roots. Severely infected plants died. Diseased tissue was disinfested for 10 s in 1% NaOCl, rinsed with sterile water, and plated on potato dextrose agar (PDA) amended with 25 mg/liter of streptomycin sulfate. A fungus with morphological characters of Rhizoctonia solani (3) was consistently recovered. Ten-day-old mycelium grown on PDA at 22 ± 1°C appeared light brown, rather compact, and with radial growth. Sclerotia were irregular and measured between 0.5 and 2 mm. Pairings were made with tester isolates of AG 1, 2, 3, 4, 5, 6, 7, 11, and AG B1. The only successful anastomosis was with tester isolate AG 1 (ATCC 58946). The hyphal diameter at the point of anastomosis was reduced, the anastomosis point was obvious, and cell death of adjacent cells was observed. Results were consistent with other reports on anastomosis reactions (2). The description of sclerotia of the isolate AG1 was typical for subgroup 1A Type 2 (3). The internal transcribed spacer (ITS) region of rDNA was amplified using primers ITS4/ITS6 and sequenced. BLASTn analysis (1) of the 688 bp showed a 100% homology with the sequence of R. solani AG-1A and the nucleotide sequence has been assigned (GenBank Accession No. HM044764). For pathogenicity tests, the inoculum of one isolate of R. solani from the nursery was prepared by growing the pathogen on PDA for 7 days. The foliage of 30-day-old potted plants of S. nemorosa cv. Blau Koenigin was artificially inoculated with an aqueous suspension of PDA and mycelium fragments (1 g per mycelium per plant) prepared from cultures with a blender. Plants were covered with plastic bags for 3 days. Plants inoculated with water and PDA fragments alone served as control treatments. Plants were maintained in a glasshouse at 20 to 25°C. The first symptoms, similar to those observed in the nursery, developed 7 days after foliar inoculation. R. solani was consistently reisolated from infected leaves. Control plants remained healthy. The pathogenicity test was carried out twice with similar results. To our knowledge, this is the first report of leaf blight of S. nemorosa caused by R. solani in Italy as well as worldwide. The importance of the disease is still unknown. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) D. E. Carling. Page 35 in: Rhizoctonia Species: Taxonomy, Molecular Biology, Ecology, Pathology and Disease Control. Kluwer Academic Publishers, the Netherlands, 1996. (3) B. Sneh et al. Identification of Rhizoctonia Species. The American Phytopathological Society, St Paul, MN, 1991.

First Report of Leaf Spot Caused by Phoma multirostrata on Fuchsia × hybrida in Italy

Fuchsia × hybrida (Onagraceae) is widely used in gardens and very much appreciated as a potted plant. During the summer of 2008, a severe foliar disease was observed on 1- to 2-year-old plants in several gardens located near Biella (northern Italy). Small necrotic spots were observed on the upper and lower sides of infected leaves. Spots enlarged to form round areas of 2 to 12 mm in diameter and were well defined by a brown-purple margin at temperatures between 15 and 25°C. Severely infected leaves wilted and abscised as disease progressed. The disease occurred on 100% of the plants and at least 30% of the leaf surface was affected. Stems and flowers were not affected by the disease. A fungus was consistently isolated from infected leaves on potato dextrose agar amended with 25 mg/liter of streptomycin. The fungus was grown on leaf extract agar, including 30 g of autoclaved fuchsia leaves per liter, and maintained at 22°C (12-h light, 12-h dark). After 30 days, black pycnidia 150 to 450 μm in diameter developed, releasing abundant hyaline, elliptical, nonseptate conidia measuring 5.6 to 14.3 (10.3) × 1.9 to 5.6 (3.5) μm. On the basis of these morphological characteristics, the fungus was identified as a Phoma sp. (2). The internal transcribed spacer (ITS) region of rDNA of the isolate coded FuHy1 was amplified using primers ITS4/ITS6 (3) and sequenced. BLAST analysis (1) of the 488-bp segment obtained showed an E-value of 0.0 with Phoma multirostrata. The nucleotide sequence has been assigned GenBank Accession No. GU220539. Pathogenicity tests were performed by spraying leaves of healthy 6-month-old potted Fuchsia × hybrida plants with a spore and mycelial suspension (1 × 10⁶ spores or mycelial fragments per milliliter). Noninoculated plants sprayed with water served as controls. Five plants were used for each treatment. Plants were covered with plastic bags for 5 days after inoculation and kept under greenhouse conditions at 20 to 24°C. Symptoms previously described developed on leaves 12 days after inoculation, whereas control plants remained healthy. The fungus was consistently reisolated from the lesions of the inoculated plants. The pathogenicity test was carried out twice. To our knowledge, this is the first report of the presence of P. multirostrata on fuchsia in Italy as well as worldwide. The importance of the disease is still limited in Italy. References: (1) S. F. Altschud et al. Nucleic Acids Res. 25:3389, 1997. (2) G. H. Boerema and G. J. Bollen. Persoonia 8:111, 1975. (3) D. E. L. Cooke and J. M. Duncan. Mycol. Res. 101:667, 1997.

First Report of Fusarium Wilt of Endive (Cichorium endivia) Caused by Fusarium oxysporum in Italy

In the summer of 2007, a wilt of endive (Cichorium endivia) cv. Myrna plants was observed on several commercial farms near Alessandria in northern Italy. Approximately 40% of the plants on each farm were symptomatic. Affected plants were stunted and yellow and their root systems were poorly developed. Basal leaves eventually wilted. Black streaks were observed in the proximal part of the leaf vascular system. Fusarium oxysporum was consistently isolated from symptomatic vascular tissue on a Fusarium-selective medium (1). To confirm identification of the pathogen, the translation elongation factor 1α and the ribosomal DNA intergenic spacer (IGS) region were partially sequenced (2). Genomic DNA was extracted from mycelia growing on potato dextrose agar. Amplification of the EF-1α region generated a sequence of 648 bp; the IGS amplicon was 2,500 bp. The EF-1α sequence (GenBank Accession No GQ398152) was 99% similar to the sequence of a F. oxysporum strain isolated from soil and a strain pathogenic on cotton plants (GenBank Accession No. EU246574). The IGS sequence (GenBank Accession No GQ398153) was 97% similar to the sequence of a F. oxysporum strain (GenBank Accession No. EF661647). Pathogenicity tests were conducted on 15-day-old endive plants (cv. Myrna). Ten plants were inoculated by dipping their roots in a 1 × 10⁶ CFU/ml suspension of one of the isolates recovered from a wilted endive plant. Inoculated and noninoculated plants were transplanted into pots filled with steamed soil and maintained in a glasshouse at 23 to 28°C. Wilt symptoms and vascular discoloration of the roots, crown, and veins developed 60 days after inoculation. F. oxysporum was consistently reisolated from infected plants. Noninoculated plants remained healthy. The pathogenicity test was conducted twice. To our knowledge, this is the first report of wilt caused by F. oxysporum on endive in Italy. References: (1) H. Komada. Rev. Plant Prot. Res. 8:114, 1975. (2) G. Mbofung et al. Phytopathology 97:87, 2007.

First Report of Leaf Spot Caused by Pseudomonas cichorii on Coreopsis lanceolata in Italy

Coreopsis lanceolata L. (Compositae), an ornamental species grown in parks and gardens, is very much appreciated for its long-lasting flowering period. In August of 2008, pot-grown plants with necrotic leaf lesions were observed in a commercial nursery located near Biella (northern Italy). Lesions were present, especially along the margin of basal leaves, and sometimes had a chlorotic halo. On infected leaves, dark brown necrosis developed. Leaf stalks were sometimes affected. In many cases, the leaves, especially those at collar level, were withered. Of 1,500 plants, 15% were infected by the disease. Microscopic examination did not reveal any fungal structures within the lesions. Small fragments of tissue from 30 affected leaves were macerated for 15 min in casein hydrolysate and 0.1-ml aliquots of the resulting suspension were spread onto Luria Bertani agar (LB) and potato dextrose agar (PDA). Plates were maintained at 22 ± 1°C for 48 h. No fungi were isolated from the leaf spots on LB or PDA. Colonies similar to those of Pseudomonas spp. were consistently isolated on LB. Colonies were fluorescent on King's medium B, levan negative, oxidase positive, potato soft rot negative, arginine dihydrolase negative, and tobacco hypersensitivity positive (LOPAT test). The bacterial colonies were identified as Pseudomonas cichorii (2). The internal transcribed spacer (ITS) region of rDNA was amplified using primers 27F and 1492R and sequenced (GenBank Accession No. FJ534557). BLAST analysis (1) of the 998-bp segment showed a 98% homology with the sequence of P. cichorii. The pathogenicity of one isolate was tested twice by growing the bacterium in nutrient broth shake cultures for 48 h at 20 ± 1°C. The suspension was centrifuged, the cell pellet resuspended in sterile water to a concentration of 10⁷ CFU/ml, and 30 4-month-old healthy coreopsis plants were sprayed with the inoculum. The same number of plants was sprayed with sterile nutrient broth as a control. After inoculation, plants were covered with plastic bags for 48 h and placed in a growth chamber at 20 ± 1°C. Five days after inoculation, lesions similar to those seen in the field were observed on all plants inoculated with the bacterium, but not on the controls. Ten days later, 40% of the leaves were withered. Isolations were made from the lesion margins on LB and the resulting bacterial colonies were again identified as P. cichorii. The pathogen caused the same symptoms also on plants of Dendranthema frutescens (cv. Camilla), Chrysanthemum morifolium (cvs. Eleonora and Captiva), and an Osteospermum sp. (cv. Wild side) when artificially inoculated with the pathogen with the same methodology. The same bacterial leaf spot caused by P. cichorii was observed in 2005 in other nurseries in the same area on Phlox paniculata (3). To our knowledge, this is the first report of bacterial leaf spot caused by P. cichorii on C. lanceolata in Italy. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) H. Bergey et al. Bergey's Manual on Determinative Bacteriology. Williams and Wilkins, Baltimore, MD, 1994. (3) A. Garibaldi et al. Plant Dis. 89:912, 2005.

First Report of Leaf Blight on Fan Columbine (Aquilegia flabellata) Caused by Rhizoctonia solani AG 4 in Italy

Aquilegia flabellata (Ranunculaceae), fan columbine, is a perennial herbaceous plant with brilliant blue-purple flowers with white petal tips. It can also be grown for cut flower production. In April of 2008, in several nurseries located near Biella (northern Italy), a leaf blight was observed on 10 to 15% of potted 30-day-old plants grown on a sphagnum peat substrate at 15 to 20°C and relative humidity of 80 to 90%. Semicircular, water-soaked lesions developed on leaves just above the soil line at the leaf-petiole junction and later along the leaf margins. Lesions expanded over several days along the midvein until the entire leaf was destroyed. Blighted leaves turned brown, withered, and abscised. Severely infected plants died. Diseased tissue was disinfested for 10 s in 1% NaOCl, rinsed with sterile water, and plated on potato dextrose agar (PDA) amended with 25 mg/liter streptomycin sulfate. A fungus with the morphological characteristics of Rhizoctonia solani was consistently recovered, then transferred and maintained in pure culture. Ten-day-old mycelium grown on PDA at 22 ± 1°C appeared light brown, rather compact, and had radial growth. Sclerotia were not present. Isolates obtained from affected plants successfully anastomosed with tester isolate AG 4 (AG 4 RT 31, obtained from tobacco plants). Results were consistent with other reports on anastomosis reactions (2). Pairings were also made with tester isolates of AG 1, 2.1, 2.2, 3, 6, 7, 11, and BI with no anastomoses observed between the recovered and tester isolates. The internal transcribed spacer (ITS) region of rDNA was amplified using primers ITS4/ITS6 and sequenced. BLASTn analysis (1) of the 648-bp fragment showed a 100% homology with the sequence of R. solani AG-4 AB000018. The nucleotide sequence has been assigned GenBank Accession No. FJ 534555. For pathogenicity tests, the inoculum of R. solani was prepared by growing the pathogen on PDA for 10 days. Five plants of 30-day-old A. flabellata were grown in 3-liter pots. Inoculum consisting of an aqueous suspension of PDA and mycelium disks (5 g of mycelium + agar per plant) was placed at the collar of plants. Five plants inoculated with water and PDA fragments alone served as control treatments. Plants were maintained in a greenhouse at temperatures between 20 and 24°C. The first symptoms, similar to those observed in the nursery, developed 7 days after the artificial inoculation. R. solani was consistently reisolated from infected leaves and stems. Control plants remained healthy. The pathogenicity test was carried out twice with similar results. The presence of R. solani AG1-IB on A. flabellata has been reported in Japan (4), while in the United States, Rhizoctonia sp. is described on Aquilegia sp. (3). This is, to our knowledge, the first report of leaf blight of A. flabellata caused by R. solani in Italy as well as in Europe. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) D. E. Carling. Grouping in Rhizoctonia solani by hyphal anastomosis reactions. In: Rhizoctonia Species: Taxonomy, Molecular Biology, Ecology, Pathology and Disease Control. Kluwer Academic Publishers, The Netherlands, 1996. (3) D. F. Farr et al. Fungi on Plants and Products in the United States. The American Phytopathological Society, St Paul, MN, 1989. (4) E. Imaizumi et al. J. Gen. Plant Pathol. 66:210, 2000.

Report of Leaf Blight on Washington Lupine (Lupinus polyphyllus) Caused by Rhizoctonia solani AG 4 in Italy

Lupinus polyphyllus (Leguminosae), Washington lupine, is a perennial herbaceous plant. In March 2008, in a campus greenhouse at the University of Torino, Grugliasco (northern Italy), a leaf blight was observed on 20% of potted 30-day-old plants. Semicircular, water-soaked lesions developed on leaves just above the soil line at the leaf-petiole junction and later along the leaf margins. Lesions expanded for several days along the midvein until the entire leaf was destroyed. Blighted leaves turned brown, withered, clung to the shoots, and matted on the surrounding foliage. Severely infected plants died. Plants were grown in a sphagnum peat/perlite/clay (70:20:10) substrate at temperatures between 18 and 25°C and relative humidity of 60 to 80%. Diseased tissue was disinfested for 10 s in 1% NaOCl, rinsed with sterile water, and plated on potato dextrose agar (PDA) amended with 25 mg/liter of streptomycin sulfate. A fungus with the morphological characteristics of Rhizoctonia solani (4) was consistently and readily recovered, then transferred and maintained in pure culture. Ten-day-old mycelium grown on PDA at 20 ± 1°C appeared light brown, rather compact, and exhibited radial growth. The isolates of R. solani successfully anastomosed with tester isolate AG 4 (AG 4 RT 31, obtained from tobacco plants). The hyphal diameter at the point of anastomosis was reduced, the anastomosis point was obvious, and cell death of adjacent cells was observed. Results were consistent with other reports on anastomosis reactions (3). Pairings were also made with tester isolates AG 1, 2.1, 2.2, 3, 6, 7, 11, and BI with no anastomoses observed between the recovered and tester isolates. The internal transcribed spacer (ITS) region of rDNA was amplified using primers ITS4/ITS6 and sequenced. BLASTn analysis (1) of the 660-bp fragment showed 100% homology with the sequence of R. solani. The nucleotide sequence has been assigned GenBank Accession No. FJ486272. For pathogenicity tests, the inoculum of R. solani was prepared by growing the pathogen on PDA for 10 days. Plants of 30-day-old L. polyphyllus were grown in 10-liter containers (10 plants per container) on a steam disinfested sphagnum peat/perlite/clay (70:20:10) medium. Inoculum, consisting of an aqueous suspension of mycelium disks prepared from PDA cultures (5 g of mycelium per plant), was placed at the collar of plants. Plants inoculated with water and PDA fragments alone served as control treatments. Three replicates were used. Plants were maintained in a greenhouse at temperatures between 18 and 23°C. First symptoms, similar to those observed in the nursery, developed 10 days after the artificial inoculation. R. solani was consistently reisolated from infected leaves and stems. Control plants remained healthy. The pathogenicity test was repeated twice. The susceptibility of L. polyphyllus to R. solani was reported in Poland (2). This is, to our knowledge, the first report of leaf blight of L. polyphyllus caused by R. solani in Italy. The importance of the disease is at the moment limited. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) W. Blaszczak. Rocz. Nauk. Roln. Ser A 85:705, 1962. (3) D. E. Carling. Grouping in Rhizoctonia solani by hyphal anastomosis reactions. In: Rhizoctonia Species: Taxonomy, Molecular Biology, Ecology, Pathology and Disease Control. Kluwer Academic Publishers, The Netherlands, 1996. (4) B. Sneh et al. Identification of Rhizoctonia species. The American Phytopathological Society, St Paul, MN, 1991.

First Report of Leaf Blight on Foxglove (Digitalis purpurea) Caused by Rhizoctonia solani AG-1-IA in Italy

Digitalis purpurea (Scrophulariaceae), foxglove, is used in flower gardens. In the spring of 2008, leaf blight was observed in a nursery near Biella (northern Italy) on 30% of potted 30-day-old plants grown in a peat substrate at temperatures from 20 to 25°C and relative humidity at 75 to 80%. Semicircular, water-soaked lesions developed on leaves just above the soil line at the blade-petiole junction and later along the leaf margins. Lesions expanded for several days along the midvein until the entire leaf was affected. Blighted leaves turned brown, withered, clung to the shoots, and matted on the surrounding foliage. Diseased tissue was disinfested for 10 s in 1% NaOCl, rinsed with sterile water, and plated on potato dextrose agar (PDA) amended with 100 mg/liter of streptomycin sulfate. A fungus with the morphological characteristics of Rhizoctonia solani was consistently and readily recovered, then transferred and maintained in pure culture (4). The isolates of R. solani obtained from affected plants successfully anastomosed with tester isolate AG 1 (ATCC 58946). The hyphal diameter at the point of anastomosis was reduced, the anastomosis point was obvious, and cell death of adjacent cells was observed. Results were consistent with other reports on anastomosis reactions (2). Pairings were also made with tester isolates AG 2, 3, 4, 6, 7, 11, and AG BI and anastomosis was not observed. Ten-day-old colonies grown on PDA appeared light brown, rather compact, and radial. Numerous sclerotia of uniform size (0.5 to 3 mm in diameter) and sometimes joined laterally were formed. Descriptions of mycelium and sclerotia were typical for subgroup IA Type 2 (4). The internal transcribed spacer (ITS) region of rDNA was amplified using primers ITS4/ITS6 and sequenced. BLASTn analysis (1) of the 724-bp fragment showed a 99% homology with the sequence of R. solani (GenBank Accession No. EU591800). The nucleotide sequence has been assigned GenBank Accession No. FJ467490. For pathogenicity tests, the inoculum of R. solani was prepared by growing the pathogen on PDA for 10 days. Plants of 30-day-old D. purpurea were grown in 10-liter containers (6 plants per container) in a steam disinfested peat/clay/perlite (70:20:10) substrate. Disks of PDA cultures were placed on leaves (1 cm² of mycelium per plant). Plants inoculated with PDA alone served as control treatments. Three replicates were used. Plants were maintained in a growth chamber at 24 ± 1°C with 12 h light/dark. First symptoms developed 12 days after the artificial inoculation. R. solani was consistently reisolated from infected leaves and stems. Control plants remained healthy. The pathogenicity test was repeated twice. R. solani was isolated from a small percentage of infected seeds of D. purpurea in India (3). This is, to our knowledge, the first report of leaf blight of D. purpurea caused by R. solani in Italy as well as in Europe. The spread of R. solani in nurseries might cause a decrease in trade. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) D. E. Carling. Grouping in Rhizoctonia solani by hyphal anastomosis reactions in: Rhizoctonia Species: Taxonomy, Molecular Biology, Ecology, Pathology and Disease Control. Kluwer Academic Publishers, the Netherlands, 1996. (3) K. K. Janardhanan and D. Ganguly. Indian Phytopathol. 16:379, 1963. (4) B. Sneh et al. Identification of Rhizoctonia Species. The American Phytopathological Society, St Paul, MN, 1991.