Didymella corylicola sp. nov., a new fungus associated with hazelnut fruit development in Italy

A new fungal species constantly associated with hazelnut (Corylus avellana) fructification starting from its primordia is described. The fungus is associated with hazelnut fruit during all their developmental stages, being consistently more present in spring (March–June). A 4-year survey has been conducted, from young fruit formation to full kernel maturity including also the post-harvest phase, to collect fungi associated with damaged/discoloured kernels. A collection of 60 isolates of a new species has been obtained in this study, which is here described as Didymella corylicola sp. nov. Multi-locus phylogenies based on four genomic loci (nuITS and LSU rDNA, RPB2 and TUB2) in combination with morphological data confirmed the fungus to represent a new species of Didymella (Didymellaceae). The occurrence of D. corylicola sp. nov. might have an impact on the quality of hazelnut production by contributing to kernel defects.

Liberomycespistaciae sp. nov., the causal agent of pistachio cankers and decline in Italy

A new canker and decline disease of pistachio (Pistaciavera) is described from Sicily (Italy). Observations of the disease and sampling of the causal agent started in spring 2010, in the area where this crop is typically cultivated, Bronte and Adrano (Catania province) and later extended to the Agrigento and Caltanissetta provinces. Isolations from the margins of twig, branch and stem cankers of declining plants resulted in fungal colonies with the same morphology. Pathogenicity tests on 5-year-old potted plants of Pistaciavera grafted on P.terebinthus reproduced similar symptoms to those observed in nature and the pathogen was confirmed to be a coloniser of woody plant tissue. Comparison of our isolates with the type of the apparently similar Asteromellapistaciarum showed that our isolates are morphologically and ecologically different from A.pistaciarum, the latter being a typical member of Mycosphaerellaceae. Asteromellapistaciarum is lectotypified, described and illustrated and it is considered to represent a spermatial morph of Septoriapistaciarum. Multi-locus phylogenies based on two (ITS and LSU rDNA) and three (ITS, rpb2 and tub2) genomic loci revealed isolates of the canker pathogen to represent a new species of Liberomyces within the Delonicicolaceae (Xylariales), which is here described as Liberomycespistaciaesp. nov. (Delonicicolaceae, Xylariales). The presence of this fungus in asymptomatic plants with apparently healthy woody tissues indicates that it also has a latent growth phase. This study improves the understanding of pistachio decline, but further studies are needed for planning effective disease management strategies and ensuring that the pathogen is not introduced into new areas with apparently healthy, but infected plants.

First Report of Phytophthora megasperma Causing Decline and Death on Celtis australis in Italy

European hackberry (Celtis australis L.) is a popular shade tree mainly planted in southern Europe and known to be tolerant to dry and poor soils. In early autumn 2013, hackberry plants grown in soil in a commercial nursery located in the floodplain in Umbria region showed symptoms of wilting, dieback, and death. Up to 100% of the canopy was affected, and over 60% of the plants were symptomatic or dead. A Phytophthora species was consistently isolated from symptomatic 6-year-old plants by plating small pieces of collar and root tissues, cut from the margin of dark-brown necrotic lesions, onto P₅ARPH selective medium (4). Pure cultures were obtained by single-hyphal transfers on potato dextrose agar (PDA). Sporangia, produced on pepper seeds in soil extract solution (3), were nonpapillate and noncaducous, measuring 34.0 to 85.0 × 22.0 to 50.0 μm. Oospores had an average diameter of 44 μm with mostly paragynous antheridia. On the basis of morphological features, the isolates were identified as P. megasperma Drech. (2). The identity was confirmed by sequencing the cytochrome c oxidase subunit II (Cox II) (5), which gave 100% identity with P. megasperma sequences available in GenBank (GU222070), and by sequencing the internal transcribed spacer (ITS) using the universal primers ITS4 and ITS6, which gave 99% identity with the AF266794 sequence from Cooke et al. (1). The sequences of one isolate (AB239) were deposited in the European Nucleotide Archive (ENA) with accession numbers HG973451 and HG973450 for Cox II and ITS, respectively. Pathogenicity tests were conducted in the greenhouse with isolate AB239 on eight 2-year-old potted European hackberry plants. Mycelial plugs (5 mm diameter) cut from the margins of actively growing 8-day-old cultures on PDA were inserted through the epidermis to the phloem at the collar level. Two plants were used as controls and treated as described above except that sterile PDA plugs replaced the inoculum. Inoculated plants were kept for 4 weeks in a greenhouse at 24 ± 2°C. During that period, inoculated plants showed wilting symptoms similar to those observed in the field. Lesions were evident at all the inoculation points progressing downward to the roots. Colonies of Phytophthora were isolated from the margins of lesions and identified as P. megasperma, thus fulfilling Koch's postulates. Controls remained symptomless. P. megasperma taxonomy is rather complex since it embraces different subgroups, including host specialized forms (formae speciales), some of which are recognized as biological species. Based on morphological and molecular data presented here, the Phytophthora isolates from hackberry belong to P. megasperma sensu stricto, which is included in the "pathogenic to a broad range of hosts" (BHR) group (1). This pathogen is rather polyphagous, attacking mainly fruit and ornamental woody plants, commonly Prunus spp., Malus spp., and Actinidia deliciosa. Like other homothallic Phytophthora species, it is particularly dangerous due to its abundant production of thick-walled resting oospores that enable long-term survival in the soil. To our knowledge this is the first report of P. megasperma sensu stricto (1) on C. australis and its family Ulmaceae/Cannabaceae. References: (1) D. E. L. Cooke et al. Fungal Genet. Biol. 30:17, 2000. (2) D. C. Erwin and O. K. Ribeiro, American Phytopathological Society, St. Paul, MN, 1996. (3) E. Ilieva et al. Eur. J. Plant Path. 101:623, 1995. (4) S. N. Jeffers and S. B. Martin. Plant Dis. 70:1038, 1986. (5) F. N. Martin and P. W. Tooley. Mycologia 95:269, 2003.

First Report of Phytophthora hydropathica Causing Wilting and Shoot Dieback on Viburnum in Italy

The genus Viburnum comprises over 150 species of shrubs and small trees such as Laurustinus (Viburnum tinus L.), which is one of the most widely used ornamental plants in private and public gardens. Furthermore, it commonly forms stands of natural woodland in the Mediterranean area. In autumn 2012, a survey was conducted to determine the presence of Phytophthora ramorum on Viburnum in commercial nurseries in the Latium region where wilting, dieback, and death of twigs were observed on 30% of the Laurustinus plants. A Phytophthora species was consistently recovered from soil rich in feeder roots from potted Laurustinus plants showing symptoms. Soil samples were baited with rhododendron leaves. Small pieces of leaf tissue cut from the margin of lesions were plated on P₅ARPH selective medium (4). Pure cultures, obtained by single-hypha transfers on potato dextrose agar (PDA), were petaloid. Sporangia formation was induced on pepper seeds (3). Sporangia were almost spherical, ovoid or obpyriform, non-papillate and non-caducous, measuring 36.6 to 71.4 × 33.4 to 48.3 μm (average 53.3 × 37.4 μm) with a length/width ratio of 1.4. Chlamydospores were terminal and 25.2 to 37.9 μm in diameter. Isolates were considered heterothallic because they did not produce gametangia in culture or on the host. All isolates examined had 30 to 35°C as optimum temperatures. Based on these morphological characteristics, the isolates were identified as Phytophthora hydropathica (2). Morphological identification was confirmed by internal transcribed spacer (ITS), and mitochondrial partial cytochrome oxidase subunit 2 (CoxII) with BLAST analysis in the NCBI database revealing 99% identity with ITS and 100% identity with CoxII. The sequences of the three isolates AB234, AB235, and AB236 were deposited in European Nucleotide Archive (ENA) with the accession nos. HG934148, HG934149, and HG934150 for ITS and HG934151, HG934152, and HG934153 for CoxII, respectively. Pathogenicity tests were conducted in the greenhouse on a total of six 1-year-old shoots cut from V. tinus plants with two inoculation points each. Mycelial plugs cut from the margins of actively growing 8-day-old cultures on PDA were inserted through the epidermis into the phloem. Controls were treated as described above except that sterile PDA plugs replaced the inoculum. Shoots were incubated in test tubes with sterile water in the dark at 24 ± 2°C. After 2 weeks, lesions were evident at the inoculation points and symptoms were similar to those caused by natural infection. P. hydropathica was consistently re-isolated from the margin of lesions, while controls remained symptomless. In the United States in 2008, P. hydropathica was described as spreading from irrigation water to Rhododendron catawbiense and Kalmia latifolia (2). This pathogen can also attack several other horticultural crops (1), but to our knowledge, this is the first report of P. hydropathica causing wilting and shoot dieback on V. tinus. References: (1) C. X. Hong et al. Plant Dis. 92:1201, 2008. (2) C. X. Hong et al. Plant Pathol. 59:913, 2010. (3) E. Ilieva et al. Eur. J. Plant Path. 101:623, 1995. (4) S. N. Jeffers and S. B. Martin. Plant Dis. 70:1038, 1986.

First Report of Phytophthora tropicalis on Rhododendron in Italy

The genus Rhododendron comprises over 1,000 species, which represent many important ornamental shrubs. Microbial isolations were made from Rhododendron catawbiense plants showing symptoms of wilt, dieback, and death of shoots obtained from two nurseries in the Latium region in the late summer of 2012. A Phytophthora species was consistently recovered by plating small pieces of stem and collar tissues, cut from the margin of lesions, on P₅ARPH selective medium. Pure cultures were obtained by single-hyphal transfers and they grew in a rosaceous pattern on potato dextrose agar (PDA) at an optimum temperature of 28 to 30°C. Sporangia formation was induced on pepper seeds (3). Sporangia were ellipsoid, fusiform or obpyriform, papillate, occasionally bipapillate, caducous, with a long pedicel (up to 100 μm), and mean dimensions of 45 × 25 μm with a mean length/width ratio of 1.8. Chlamydospores ranged from 25 to 32 μm in diameter. Isolates were considered heterothallic because they did not produce gametangia in vitro or in planta. On the basis of morphological features, the isolates were identified as Phytophthora tropicalis Aragaki & Uchida. Identity was confirmed by sequence comparison in GenBank with 99% homology both for internal transcribed spacer (ITS) and mitochondrial partial COI for cytochrome oxidase subunit 1. The sequences of two isolates AB211 and AB212 were deposited in the European Nucleotide Archive (ENA) with accession nos. HF937577 and HF937578 for ITS, and HF937579 and HF937580 for COI, respectively. Pathogenicity tests were conducted in the greenhouse on a total of six 1-year-old shoots cut from R. catawbiense plants with two inoculation points each. Mycelial plugs cut from the margins of actively growing 8-day-old cultures on PDA were inserted through the epidermis to the phloem. Controls were treated as described above except for inoculation with sterile PDA plugs. Inoculated shoots were incubated in test tubes with sterile water for 1 week in the dark at 26 ± 2°C. Lesions were evident at the inoculation points. P. tropicalis was consistently reisolated from the margin of symptomatic tissues. Control shoots remained symptomless. In Italy, P. tropicalis has been reported on several ornamental species (1) and on apricot trees (4) indicating a broad host range. On the same host it has been reported in Virginia, United States (2). To the best of our knowledge, this is the first report of Phytophthora damage on Rhododendron caused by P. tropicalis in Italy. References: (1) S. O. Cacciola et al. Plant Dis. 90: 680, 2006. (2) C. X. Hong et al. Plant Dis. 90: 525, 2006. (3) E. Ilieva et al. Eur. J. Plant Path. 101: 623, 1995. (4) A. Pane et al. Plant Dis. 93: 844, 2009.

A newly developed real-time PCR assay for detection and quantification of Fusarium oxysporum and its use in compatible and incompatible interactions with grafted melon genotypes

A reliable and species-specific real-time quantitative polymerase chain reaction (qPCR) assay was developed for detection of the complex soilborne anamorphic fungus Fusarium oxysporum. The new primer pair, designed on the translation elongation factor 1-α gene with an amplicon of 142 bp, was highly specific to F. oxysporum without cross reactions with other Fusarium spp. The protocol was applied to grafted melon plants for the detection and quantification of F. oxysporum f. sp. melonis, a devastating pathogen of this cucurbit. Grafting technologies are widely used in melon to confer resistance against new virulent races of F. oxysporum f. sp. melonis, while maintaining the properties of valuable commercial varieties. However, the effects on the vascular pathogen colonization have not been fully investigated. Analyses were performed on 'Charentais-T' (susceptible) and 'Nad-1' (resistant) melon cultivars, both used either as rootstock and scion, and inoculated with F. oxysporum f. sp. melonis race 1 and race 1,2. Pathogen development was compared using qPCR and isolations from stem tissues. Early asymptomatic melon infections were detected with a quantification limit of 1 pg of fungal DNA. The qPCR protocol clearly showed that fungal development was highly affected by host-pathogen interaction (compatible or incompatible) and time (days postinoculation). The principal significant effect (P ≤ 0.01) on fungal development was due to the melon genotype used as rootstock, and this effect had a significant interaction with time and F. oxysporum f. sp. melonis race. In particular, the amount of race 1,2 DNA was significantly higher compared with that estimated for race 1 in the incompatible interaction at 18 days postinoculation. The two fungal races were always present in both the rootstock and scion of grafted plants in either the compatible or incompatible interaction.

First Report of Phytophthora megasperma Associated with Decline and Death of Common Walnut Trees in Italy

Common walnut (Juglans regia L.) is an important nut crop in Italy, which is the fifth largest producer of walnut in Europe. In recent years, walnut decline and subsequent death has increased in many Italian commercial orchards. In the summer of 2010, several declining trees were present in waterlogged area of a walnut orchard located in the Veneto region. Symptoms included sparse foliage, wilting, and shoot and branch dieback. By the next year, a larger area of about 1 ha with 20% of dead trees was present, and soil/root samples were subjected to azalea leaf baiting and successively cultured on PARBH medium (3). Isolates were identified as Phytophthora megasperma based on morphological characteristics (2) and DNA sequence analysis. Sporangia were 35.0 to 62.0 × 12.0 to 30.0 μm, nonpapillate, and noncaducous when produced in soil extract solution. Oogonia had an average diameter of 36 μm with mostly paragynous antheridia. Identity was confirmed by sequence comparison in NCBI database with 99% and 100% identity for internal transcribed spacer (ITS) and mitochondrial partial COI (4) for cytochrome oxidase subunit 1, respectively. The sequences of the isolate AB199 were deposited in GenBank with the accession nos. HE805270 and HE805269 for ITS and COI, respectively. Pathogenicity tests were conducted in the greenhouse on six 1-year-old walnut shoots with two inoculation points each. Mycelial plugs cut from the margins of actively growing 8-day-old cultures on PDA were inserted through the epidermis to the phloem. Controls were treated as described above except for inoculation with sterile PDA plugs. After inoculation, shoots were incubated in test tubes with sterile water for 1 week in the dark at 22 ± 2°C. Lesions were evident at the inoculation points. P. megasperma was consistently reisolated from the margin of symptomatic tissues. Controls remained symptomless. P. megasperma is a polyphagous, ubiquitarious Phytophthora species that attacks many crops and fruit species including walnut. Although several other species of Phytophthora have been reported from Italy (1), to the best of our knowledge, this is the first report of Phytophthora decline on common walnut in Italy caused by P. megasperma. References: (1) A. Belisario et al. Acta Hort. 705:401, 2006. (2) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (3) G. C. Papavisas et al. Phytopathology 71:129, 1981. (4) G. P. Robideau et al. Mol. Ecol. Resour. 11:1002, 2011.

Mechanisms governing the responses to anthracnose pathogen in Juglans spp

Juglans nigra and Juglans regia are two highly economically important species for wood and fruit production that are susceptible to anthracnose caused by Gnomonia leptostyla. The identification of genotypes resistant to anthracnose could represent a valid alternative to agronomic and chemical management. In this study, we analyzed 72 walnut genotypes that showed a variety of resistance phenotypes in response to natural infection. According to the disease severity rating and microsatellite fingerprinting analysis, these genotypes were divided into three main groups: (40) J. nigra resistant, (1) J. nigra susceptible, and (31) J. regia susceptible. Data on leaf emergence rates and analysis of in vivo pathogenicity indicated that the incidence of anthracnose disease in the field might be partially conditioned by two key factors: the age and/or availability of susceptible leaves during the primary infection of fungus (avoidance by late flushing) and partial host resistance. NBS profiling approach, based on PCR amplification with an adapter primer for an adapter matching a restriction enzyme site and a degenerate primer targeting the conserved motifs present in the NBS domain of NBS-LRR genes, was applied. The results revealed the presence of a candidate marker that correlated to a reduction in anthracnose incidence in 72 walnut genotypes.

Morphological and molecular analysis of Fusarium lateritium, the cause of gray necrosis of hazelnut fruit in Italy

Fusarium lateritium is a globally distributed plant pathogen. It was recently reported as the causal agent of nut gray necrosis (NGN) on hazelnut. Isolate characterization within F. lateritium was undertaken to investigate how morphological and molecular diversity was associated with host and geographic origin. Morphological studies combined with inter-simple-sequence repeat (ISSR) analysis, and phylogenetic analyses using translation elongation factor 1α (TEF-1α), β-tubulin genes, and nuclear ribosomal DNA internal transcribed spacer (ITS) sequences were conducted to resolve relationships among 32 F. lateritium isolates from NGN-affected hazelnut fruit, and 14 from other substrates or 8 from other hosts than hazelnut. Colonies of F. lateritium from hazelnut showed dark grayish-olive differing from the orange-yellow color of all other isolates from other hosts. Generally, isolates from NGN-affected fruit failed to produce sporodochia on carnation leaf agar. The influence of host and substrate on the genetic structure of F. lateritium was supported by ISSR and analyzed with principal coordinates analysis. A relationship between hazelnut and genetic variation was inferred. Phylogenetic analysis of ITS provided limited resolution while TEF-1α and β-tubulin analyses allowed a clear separation between the European and non-European F. lateritium isolates retrieved from GenBank, regardless of host. Though morphological traits of F. lateritium isolates from hazelnut were generally uniform in defining a typical morphogroup, they were not yet phylogenetically defined. In contrast, the typology related to slimy deep orange cultures, due to spore mass, grouped clearly separated from the other F. lateritium isolates and revealed a congruence between morphology and phylogeny.

Distinct colonization patterns and cDNA-AFLP transcriptome profiles in compatible and incompatible interactions between melon and different races of Fusarium oxysporum f. sp. melonis

BACKGROUND

Fusarium oxysporum f. sp. melonis Snyd. & Hans. (FOM) causes Fusarium wilt, the most important infectious disease of melon (Cucumis melo L.). The four known races of this pathogen can be distinguished only by infection on appropriate cultivars. No molecular tools are available that can discriminate among the races, and the molecular basis of compatibility and disease progression are poorly understood. Resistance to races 1 and 2 is controlled by a single dominant gene, whereas only partial polygenic resistance to race 1,2 has been described. We carried out a large-scale cDNA-AFLP analysis to identify host genes potentially related to resistance and susceptibility as well as fungal genes associated with the infection process. At the same time, a systematic reisolation procedure on infected stems allowed us to monitor fungal colonization in compatible and incompatible host-pathogen combinations.

RESULTS

Melon plants (cv. Charentais Fom-2), which are susceptible to race 1,2 and resistant to race 1, were artificially infected with a race 1 strain of FOM or one of two race 1,2 w strains. Host colonization of stems was assessed at 1, 2, 4, 8, 14, 16, 18 and 21 days post inoculation (dpi), and the fungus was reisolated from infected plants. Markedly different colonization patterns were observed in compatible and incompatible host-pathogen combinations. Five time points from the symptomless early stage (2 dpi) to obvious wilting symptoms (21 dpi) were considered for cDNA-AFLP analysis. After successful sequencing of 627 transcript-derived fragments (TDFs) differentially expressed in infected plants, homology searching retrieved 305 melon transcripts, 195 FOM transcripts expressed in planta and 127 orphan TDFs. RNA samples from FOM colonies of the three strains grown in vitro were also included in the analysis to facilitate the detection of in planta-specific transcripts and to identify TDFs differentially expressed among races/strains.

CONCLUSION

Our data suggest that resistance against FOM in melon involves only limited transcriptional changes, and that wilting symptoms could derive, at least partially, from an active plant response.We discuss the pathogen-derived transcripts expressed in planta during the infection process and potentially related to virulence functions, as well as transcripts that are differentially expressed between the two FOM races grown in vitro. These transcripts provide candidate sequences that can be further tested for their ability to distinguish between races.Sequence data from this article have been deposited in GenBank, Accession Numbers: HO867279-HO867981.

First Report of Fusarium semitectum as the Agent of Twig Cankers on Persian (English) Walnut in Italy

English (Persian) walnut (Juglans regia) is the most widely cultivated walnut species. During the last 10 years, the increment of walnut cultivation in Italy has been accompanied by changes in cultural management. Changes were addressed to develop highly specialized cultivations with intensive pruning, fertilization, irrigation, and chemical treatments. For these reasons, more consideration has been given to the sanitary situation, in particular since 1998 when brown apical necrosis (BAN) was first observed (1). BAN is a fungal complex disease causing fruit drop, in which several Fusarium spp. are involved, among which Fusarium semitectum represents one of the major causal agents (2). From 2005 onward, investigations on sources of inoculum for BAN led to observing the presence of twig cankers on walnut trees cv. Lara located in northern Italy (Po valley). Cankers observed in late spring to summer were usually small (1 to 3 cm long) and mainly occurred on the new growth strongly incited by intensive pruning. Pale orange sporodochia were evident on lesions. Isolations were made from the margins of lesions, and small fragments of tissues (approximately 3 mm) were plated onto potato dextrose agar (PDA) after surface disinfection with 1% NaOCl. Whitish, light brown colonies were consistently obtained. On PDA, the production of fusoid, 1- to 3-celled mesoconidia was abundant. This characteristic was combined with the presence of two-spored polyphialides with a "rabbit-ear" appearance. Three to five septate macroconidia (38 × 4 μm) were produced in sporodochia on carnation leaf agar (CLA). On the basis of morphological characteristics (3), the fungus was identified as F. semitectum Berk. & Ravenel (synonyms F. incarnatum and F. pallidoroseum). Sequence comparison of internal transcribed spacer (ITS) and translation elongation factor 1-alpha (TEF1-α) was used to support the identification. A 99% identity for ITS was obtained with Accession No. AY633745 from Vietnam, while for TEF 1-α, a comparison was not available in GenBank. The sequences of one isolate (ISPaVe1946) were deposited in GenBank (Accession No. FN430680 for ITS and No. FN430737 for TEF 1-α). Pathogenicity tests were conducted outdoors on 1-year-old shoots of J. regia potted plants using ISPaVe1946 single-spored isolate. Mycelial plugs of 5-mm diameter, cut from the margin of PDA actively growing cultures, were placed under the bark and protected with Parafilm to prevent desiccation. Six inoculation points were performed. Controls were inoculated with plain PDA plugs. Within 2 months after inoculation, cankers developed in all inoculated points and were similar to those observed in nature. Controls showed no symptoms. Koch's postulates were fulfilled and the pathogen was constantly reisolated from lesions. To our knowledge, this is the first report of F. semitectum as the causal agent of twig cankers on walnut in Italy. This pathogen was already reported as an agent of canker on walnut in Argentina (4). References: (1) A. Belisario et al. Inf. Agrario 21:51, 1999. (2) A. Belisario et al. Plant Dis. 86:599, 2002. (3) J. F. Leslie et al. The Fusarium Laboratory Manual. Blackwell Publishing Press Ltd, Oxford, UK, 2006. (4) S. Seta et al. Plant Pathol. 53:248, 2004.

First Report of Fusarium lateritium as the Agent of Nut Gray Necrosis on Hazelnut in Italy

Hazelnut (Corylus avellana) is a traditionally cultivated nut species in Italy. Italy is the second largest producer of hazelnut in the world after Turkey. In early summer of 2000, a severe fruit drop (up to 60%) was observed in several hazelnut orchards located in the Latium Region in central Italy. The severity of yield losses led to investigating the etiology of the disease subsequently named nut gray necrosis (NGN) based on symptoms observed on the affected fruit. Symptoms consisted of a brown grayish necrotic spot/patch on the nut shell and bracts, sometimes involving the petiole (1). Isolations of the potential pathogen were from tissue that was sampled starting from bloom of female flowers to fully ripened fruit. Isolations from symptomatic tissue consisted of placing onto potato dextrose agar (PDA) small tissue fragments (approximately 3 mm) cut from the margin of lesions, while asymptomatic material (entire flowers or young fruit) was sectioned into small pieces. All the material was previously surface disinfected with 1% NaOCl. Slow-growing, dark grayish olive colonies were obtained consistently within 14 days of incubation at 20 to 22°C from symptomatic and asymptomatic material. Sporodochia were rarely produced on PDA, but never on carnation leaf agar. Dark grayish olive colonies were assigned to a Fusarium sp. Detached hazelnut fruit exposed to 20 μl of a mycelial suspension (10⁵ CFU/ml) and incubated in a moist chamber at room temperature for 10 days produced orange sporodochia bearing 3 to 5 septate macroconidia (35 × 4 μm). On the basis of morphology, the fungus was identified as Fusarium lateritium Nees. (3,4). The identity was confirmed by internal transcribed spacer rDNA sequence comparison with BBA65248 (GenBank Accession No. AF310980). The sequences of two isolates, ISPaVe1874 and ISPaVe1976, were deposited in GenBank (Accession Nos. FN547420 and FN547445, respectively). Pathogenicity tests were performed in planta by inoculating, with the aforementioned isolates, young to fully formed fruit (approximately 24 mm in diameter) either with a drop of mycelial (10⁶ CFU/ml) or conidial (10⁶ conidia/ml) suspension. Drops were placed between the nut and leafy involucre. Controls were treated with sterile water only. Within 2 weeks after inoculation, a grayish necrosis developed on all the inoculated fruit and was similar to symptoms originally observed in the field. No differences were observed between the two methods of inoculation. On full-sized fruit, lesions extended from the shell to inner tissues. The pathogen was consistently reisolated from lesions. Controls showed no symptoms. To our knowledge, this is the first report of F. lateritium as the causal agent of nut gray necrosis on hazelnut in Italy, and this pathogen has never been reported as an agent of necrosis and drop of hazelnut fruit, but it was previously reported as an agent of twig cankers (2). References: (1) A. Belisario et al. Inf. Agrario 59:71, 2003. (2) A. Belisario et al. Plant Dis. 89:106, 2005. (3) J. F. Leslie et al. The Fusarium Laboratory Manual. Blackwell Publishing Press Ltd, Oxford, UK, 2006. (4) P. E. Nelson et al. Fusarium Species: An Illustrated Manual for Identification. Pennsylvania State University Press, 1983.

First Report of Leaf Blight and Root and Foot Rot of a Strelitzia Caused by Phytophthora nicotianae in Italy

Bird of paradise, also known as crane flower (Strelitzia reginae Aiton), is a monocotyledonous flowering plant indigenous to South Africa. It is commonly grown and commercialized as an ornamental plant and it is appreciated for its beautiful flowers. In October of 2008, dark leaf spots and leaf blight associated with a severe root and foot rot were observed on several plants of S. reginae grown in a private garden located in Fiumicino, Italy. Small fragments of tissues (approximately 3 mm) collected from the base of leaves and roots and the margins of brown lesions, previously surface disinfected with 0.5% NaOCl, were plated onto potato dextrose agar (PDA) and incubated at 22°C in the dark. White, web-like, slow-growing colonies with coenocytic mycelium and hyphal swellings consistently developed from all plated tissue samples. Sporangia were ovoid or ellipsoid with prominent papillae (including some bipapillate) and frequently caducous with a short stalk. The dimensions of sporangia were 27 to 64 × 23 to 45 μm (average 43 × 35 μm). Chlamydospores were terminal or intercalary and approximately 30 μm in diameter. Isolates were considered heterothallic because they did not produce gametangia in vitro or in planta. On the basis of morphological features, isolates were identified as Phytophthora nicotianae (Breda de Haan). The identity was confirmed by internal transcribed spacer (ITS) sequence comparison in NCBI database with 99% identity with sequences available in GenBank (e.g., EU331089) and with cytochrome c oxidase subunit I (Cox I) with 99% identity with AY564196 by Kroon et al. (2). The sequences of one isolate, AB177, were deposited in GenBank (Accession Nos. FN430681 and FN552051 for ITS and Cox I, respectively). Pathogenicity tests were conducted in the greenhouse on leaves of a 1-year-old potted S. reginae plant by placing 5-mm-diameter mycelial plugs, cut from the margins of 10-day-old actively growing cultures, with mycelium in contact with plant tissues gently wounded with a needle. Controls were treated as described above, except that PDA sterile plugs were used. Plants were misted with water and placed in sealed plastic bags for 48 h. After 10 days, artificially wounded strelitzia leaves showed lesions (approximately 1 cm long). Controls remained symptomless. All inoculated leaves showed the same leaf symptoms as observed on naturally diseased plants. The pathogen was consistently reisolated from lesions. P. nicotianae has been reported as the causal agent of leaf blight and stem, collar, and root rot on several plants (1). It has been reported as an agent of Phytophthora blight on strelitzia in Japan (3). To our knowledge, this is the first report of P. nicotianae on strelitzia in Italy. References: (1) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (2) L. P. N. M. Kroon et al. Fungal Genet. Biol. 41:766, 2004. (3) S. Uematsu et al. Ann. Phytopathol. Soc. Jpn. 60:746, 1994.

First Report of Stemphylium vesicarium as Causal Agent of Wilting and Root Rotting of Radish Sprouts in Italy

A consistent contamination from a Stemphylium sp. was detected on radish (Raphanus sativus) seeds by a seed blotter test. Twenty-five percent of seed lots were contaminated. Stemphylium vesicarium (teleomorph Pleospora allii) was identified on the basis of morphological characters of conidia and conidiophores (4). Conidia were golden brown to dark drown, oblong to oval with one to four transverse and one to three longitudinal septa, constricted at one to three of the major transverse septa. Conidia dimensions ranged from 12 to 22 × 30 to 40 μm. Conidiophores were straight or occasionally one-branched with a swollen apex and one to four septate. Pseudothecia with asci and ascopores were observed on radish seeds. Asci were cylindrical to clavate with eight ascospores with up to six transverse septa and numerous longitudinal septa. Species identification was also confirmed after comparing the sequences of the internal transcribed spacer (ITS) region of rDNA and gpd (glyceraldehyde-3-phosphate dehydrogenase) (3) of four isolates with those of Stemphylium species already present in the NCBI database. Accessions Nos. AM 746020 to AM746023 and AM883174 to AM883177 were deposited for ITS and gpd, respectively. Artificial inoculations were carried out on radish seeds previously disinfected with 1% sodium hypochlorite for 10 min and then plated on S. vesicarium sporulating colonies grown on potato dextrose agar (PDA). The four sequenced isolates were tested for pathogenicity. Disinfected seeds were plated onto PDA only and used as a control. After 48 h of incubation, seeds were sown in sterilized soil in plastic plates. The emerging and the eventually dead plants were counted. Stem necrosis and root rotting developed on sprouts within the first week after sowing. On the surviving infected plantlets, wilting and death occurred on more than 70% of the plants within 4 weeks after sowing. Control plantlets obtained from disinfected seeds remained healthy. The fungus reisolated from wilted and dead plants was morphologically identical to the original isolates, thus confirming S. vesicarium as the causal agent. In Italy, this pathogen is common on asparagus (1), but it has also been reported on Allium spp., tomato, and pear. On European pear it is the causal agent of brown spot (2), a destructive disease in the Mediterranean area but also in the Netherlands and other continental European countries. On the basis of these results, seed contamination with S. vesicarium can represent a threat for the production of radish for sprout consumption. To our knowledge, this is the first report of S. vesicarium on radish plantlets in Italy. References: (1) F. Del Zan et al. L'informatore Agrario 11:95, 1989. (2) I. Llorente and E. Montesinos. Plant Dis. 90:1368, 2006. (3) B. M. Pryor and D. M. Bigelow. Mycologia 95:1141, 2003. (4) E. G. Simmons. Sydowia 38:284, 1985.

First Report of Zucchini Collapse by Fusarium solani f. sp. cucurbitae Race 1 and Plectosporium tabacinum in Italy

Zucchini plant collapse has been often associated with Fusarium solani f. sp. cucurbitae race 1, which is the causal agent of Fusarium crown and foot rot disease of cucurbits. In Italy, F. solani f. sp. cucurbitae race 1 has been reported on zucchini (Cucurbita pepo) in a greenhouse in the Tuscany Region (4). In spring 2005, a severe outbreak was observed on zucchini in a vast area of cultivation in the province of Venice. Isolations from necrotic vessels gave more than 20 single-spore cultures. On the basis of morphological characteristics, they were identified as F. solani (2) and Plectosporium tabacinum (3). The internal transcribed spacer (ITS) region of rDNA was amplified and sequenced. A fragment of 454 and 531 bp was 99% homologous with sequence PSU66732 and AF150472 of F. solani f. sp. cucurbitae race 1 and P. tabacinum, respectively, in the NCBI database. The nucleotide sequences have been assigned Accession No. AM408782 for F. solani f. sp. cucurbitae race 1 and AM408781 for P. tabacinum. Pathogenicity tests were conducted with four isolates of each species on 15-day-old zucchini plants and on fruit. Plants were inoculated by dipping the roots in a conidial suspension of 10⁶ spores ml^-1 for 10 min. Control plants were dipped in sterile water. Five replicates for the inoculated and control plants were used. All plants were maintained in a greenhouse at approximately 24°C. After 14 days, inoculations with F. solani f. sp. cucurbitae race 1 gave symptoms of a cortical rot at the base of the stem with a progressive yellows and wilting of leaves, while plants inoculated with P. tabacinum displayed a moderate wilting. Fruit were washed under running water, disinfected with a solution of 3% sodium hypochlorite and 5% ethanol for 1 min, and inoculated with 6-mm-diameter mycelial plugs cut from the margin of 10-day-old cultures grown on PDA. Plugs were inserted into holes (approximately 2 mm deep) made with a sterile 7-mm-diameter cork borer. Five replicates per isolate were used. Fruit were kept at room temperature (22 to 24°C) in a moist chamber. All isolates induced symptoms of fruit rotting 10 days after inoculation. All controls remained healthy. The colonies reisolated from the inoculated plants and fruit were morphologically identical to the original isolates. The results obtained proved that F. solani f. sp. cucurbitae race 1 can be considered the major pathogen in zucchini collapse, at the same time P. tabacinum may play a role in this syndrome as reported for other cucurbits (1). To our knowledge, this is the first report of zucchini plant collapse caused by F. solani f. sp. cucurbitae race 1 and P. tabacinum, and the first report of P. tabacinum on zucchini in Italy. References: (1) V. J. Garcia-Jimenez et al. EPPO Bull. 30:169, 2000. (2) P. E. Nelson et al. Fusarium Species: An Illustrated Manual for Identification. Pennsylvania State University, University Park, 1983. (3) M. E. Palm et al. Mycologia 87:397, 1995. (4) G. Vannacci and P. Gambogi. Phytopathol. Mediterr. 19:103, 1980.

Polyphasic classification of Alternaria isolated from hazelnut and walnut fruit in Europe

Brown apical necrosis of English walnut and grey necrosis of hazelnut are destructive fruit diseases caused by a complex of opportunistic fungi including several small-spored catenulate Alternaria taxa. Thirty Alternaria isolates recovered from walnut and hazelnut fruit that were pathogenic on their respective host were compared along with type or representative isolates of A. alternata, A. tenuissima, A. arborescens, and A. infectoria using morphological and molecular criteria. Morphological examination using standardized procedures separated the walnut and hazelnut isolates into three morphological groups: the A. alternata group, the A. tenuissima group, and the A. arborescens group based upon common characteristics of the conidium and the sporulation apparatus. To evaluate genetic relationships among these groups, AFLP markers, inter simple sequence repeat (ISSR) markers, and histone gene sequence data were compared. Based upon AFLP data, the A. alternata and A. tenuissima groups comprised a single lineage, and the A. arborescens group comprised a separate lineage. ISSR data supported the grouping by AFLP data except for three isolates of the A. alternata group that clustered with the A. arborescens group. Base substitution of the H4 gene supported the discrimination of the A. arborescens group from the A. alternata and A. tenuissima groups. Tests of hypotheses based upon groupings derived from the various data sets supported the discrimination of the A. arborescens group but did not support the discrimination of the A. alternata group from the A. tenuissima group.

First Report of Phytophthora cambivora Causing Bleeding Cankers and Dieback on Beech (Fagus sylvatica) in Italy

European beech (Fagus sylvatica) is an important forest tree species common in northern and central Europe. In Italy, this species is typical in mountain areas over 1,000 m above sea level. In the last decade, decline and death was reported on European beech caused by several Phytophthora species (2), and P. pseudosyringae was recently reported in Italy (3). During 2004 and 2005, seven declining and dying F. sylvatica trees, older than 20 years, were observed in the Veneto Region of Italy with symptoms of bleeding cankers at the base of trunks and on branches. Cankers on the collar showed tongue-shaped necroses of the inner bark and cambium tissues. Four trees were in a public park of Mestre and three were in a forest stand in the province of Belluno. Samples were taken from declining trees, one in the park and two in the forest. Inner bark and cambium tissue pieces were cut from the canker margins, cultured on CARPBHy-agar (corn meal agar amended with 250 μg ml^-1 ampicillin, 10 μg ml^-1 rifampicin, 10 μg ml^-1 pimaricin, 15 μg ml^-1 benomyl, 50 μg ml^-1 hymexazol), and incubated at 20°C. Ten morphologically similar isolates were subcultured as single hyphal tips and characterized. These isolates produced nonpapillate sporangia that were ovoid, obpyriform or ellipsoid, and exhibited predominately internal proliferation in soil extract. Hyphal swellings with outgrowths were present under those conditions. The morphological characteristics were consistent with those of P. cambivora (1). Base sequences of the ITS region of rDNA were determined for six of the isolates, and an 832-bp fragment was amplified for each isolate and that sequence was 100% homologous with sequences DQ396418 and AY880985 of P. cambivora in the NCBI database ( http://www.ncbi.nlm.nih.gov/BLAST/ ). The sequence of one isolate, ISPaVe 1950, was deposited in GenBank (Accession No. AM269752). Pathogenicity tests were conducted with 2-year-old potted beech seedlings. Inoculum of representative isolates was grown for 4 weeks on sterilized millet seeds moistened with V8 broth and added to soil at 3% (wt/vol). Control plants received sterilized inoculum only. The soil was flooded for 48 h. Inoculations were performed during May 2005 at 15 to 35°C with six replicates for the inoculated and control plants. The plants were maintained outdoors and assessed after 3 months. Wilt, root rot, and dark brown lesions at the collar developed on inoculated plants, but not on the controls. Symptoms were similar to those on naturally infected trees. The pathogen reisolated from the inoculated plants was morphologically identical to the original isolates, which confirmed P. cambivora as the causal agent. To our knowledge, this is the first report of P. cambivora on beech in Italy. References: (1) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (2) T. Jung et al. Mycologist, 19:159, 2005. (3) E. Motta et al. Plant Dis. 87:1005, 2003.

First Report of Twig Canker of Hazelnut Caused by Fusarium lateritium in Italy

Cultivation of hazelnut (Corylus avellana L.) has considerable economic potential in Italy, in particular, in the northern Lazio Region. Since early summer of 2000, cankered twigs have been observed on hazelnut trees that were severely affected by gray necrosis, which is a disease complex causing fruit drop (1). In subsequent years, sunken areas were observed on 1-year-old shoots from late April through May. The resulting cankers had reddish brown margins and the death of the cambium in the infected area and produced an L-shaped malformation of twigs. Girdling of the twig by the canker resulted in death of the foliage. Yellow-to-orange sporodochia were evident on cankers by early June. Isolations were made from the margins of young cankers from 20 twigs collected from 10 trees. Tissue pieces were plated onto potato dextrose agar (PDA) after surface disinfection with 1% sodium hypochlorite. Slow-growing, cream-to-reddish brown colonies with sparse aerial mycelium emerged from 80% of diseased tissue pieces within 10 days of incubation at 20 to 22°C. Conidial production was induced by keeping pure cultures at 22 to 25°C under natural light but out of direct sunlight. Within 1 month, sporodochia bearing ellipsoidal, spindle-shaped, commonly 1 to 3 septate macroconidia developed. Intercalary chlamydospores were often present in chains. Single conidia were subcultured on carnation leaf agar (CLA). On the basis of morphological and cultural characteristics, the fungus was identified as Fusarium lateritium Nees. (2). Pathogenicity tests were conducted outdoors on the current year's shoots of hazelnut trees with four isolates derived from single conidia of F. lateritium. Inocula used were either mycelial plugs cut from the margin of actively growing cultures or small (10 × 10 mm) pieces of sterile cheesecloth soaked in 1 × 10⁶ conidia per ml suspension. The mycelial plugs were placed under the bark, while the soaked cheesecloth pieces were wrapped around an area that had been wounded by gently scraping off a length of the bark (approximately 10 mm) with a sterile needle. All the inoculations were wrapped with Parafilm to prevent desiccation. Six inoculations per isolate were performed. In a similar manner, controls were inoculated with agar plugs or water only. After 3 months, the length and width of each canker were measured. For both inoculation methods, cankers were similar to those observed in nature and averaged 20.6 × 5 mm, while the controls did not show any symptoms. F. lateritium was consistently reisolated from the canker margins of the inoculated shoots. To our knowledge, this is the first report of F. lateritium causing twig cankers on hazelnut. The fungus has been reported to cause cankers on several tree species, including Malus domestica (apple), Morus spp. (mulberry), Sophora japonica (Japanese pagoda tree), Robinia pseudoacacia (black locust), Citrus spp., and Pyrus pyrifolia (Asian pear). References: (1) A. Belisario et al. Inf. Agrario 59(6):71, 2003. (2) P. E. Nelson et al. Fusarium Species: An Illustrated Manual for Identification. Pennsylvania State University, University Park, 1983.

First Report of Alternaria Species Groups Involved in Disease Complexes of Hazelnut and Walnut Fruit

During the last 5 years, two new diseases, brown apical necrosis (BAN) and gray necrosis (GN), were observed on English walnut (Juglans regia) and hazelnut (Corylus avellana), respectively (2,3). Both diseases caused severe fruit drop resulting in yield loss often exceeding 30%. Previous work demonstrated that BAN and GN are disease complexes caused by several fungi (Alternaria spp., Fusarium spp., and a Phomopsis sp.) (2,3). In both diseases, preliminary identification of Alternaria spp. revealed they were a complex of small-spored catenulate taxa related to A. alternata. To further characterize these taxa, additional pathogenicity tests and morphological examinations were conducted with isolates obtained from each host. Single-spored isolates were prescreened for pathogenicity by inoculating detached, surface-disinfested hazelnut leaves or walnut leaflets (1). Only isolates that produced foliar lesions after 5 days were used in subsequent fruit inoculations. From this screening, 35 isolates were selected (19 from walnut and 16 from hazelnut). For each isolate, attached fruit of respective hosts were inoculated at bloom by placing 10 μl of a conidial suspension (1 × 10⁶ conidia per ml of H²O + 0.26% agar) onto the stigmas (150 fruit per isolate). Controls (150 fruit) were treated with agar solution only. After 15 days, fruit were examined for development of disease symptoms, and examination continued until fruit maturation (late July). Approximately 20 to 50% of the inoculated fruit displayed discoloration or necrosis of internal tissue, particularly the pericarp and the embryo, although symptoms were more limited than those typically seen in fully expressed BAN and GN. No differences in symptoms were evident among the isolates tested. The controls showed no symptom development initially, although 5% began to develop discoloration at fruit maturity. Fungal isolates used as inoculum were reisolated from all symptomatic fruit by surface disinfesting tissue from the margins of necrotic lesions. For each isolate, the conidial characteristics were described from cultures grown under defined conditions (4). Three distinct groups of isolates were identified. Alternata sp. group isolates produced conidial chains (8 to 20 spores) with numerous secondary and occasionally tertiary chains branching from apical and median cells. Conidia were typically ovate and often possessed a one-celled apical extension. Tenuissima sp. group isolates developed conidial chains (10 to 22 spores) with occasional branching forming secondary chains from apical and median cells. Conidia were ovate to obclavate, often with long apical extensions (10 to 35 μm). Arborescens sp. group isolates developed conidial chains (5 to 12 spores) with numerous secondary, tertiary, and quaternary short chains branching from apical cells. Conidia were typically ovate with minimal apical extensions. Of the walnut isolates, 12, 4, and 3 were from the arborescens, alternata, and tenuissima sp. groups, respectively. Of the hazelnut isolates, 7, 6, and 3 were from the arborescens, alternata, and tenuissima sp. groups, respectively. The finding that Alternaria from several distinct sp. groups can cause similar disease on a single host is consistent with previous work on pistachio, almond, and pear (4). References: (1) A. Belisario et al. Plant Dis. 83:696, 1999. (2) A. Belisario et al. Plant Dis. 86:599, 2002. (3) A. Belisario et al. Inf. Agrario 59:71, 2003. (4) B. M. Pryor et al. Phytopathology 92:406, 2002.

First Report of Phytophthora nicotianae and P. citricola Associated with English Walnut Decline in Europe

English (Persian) walnut (Juglans regia), among the most widely cultivated species of Juglans worldwide, is cultivated primarily for fruit production but also for timber. In the last 10 years, walnut decline causing leaf yellowing, sparse foliage, overall decline, and plant death has increased in Italian commercial orchards. In Italy, Phytophthora cactorum, P. cambivora, P. cinnamomi, and P. cryptogea are associated with this disease (1,4). Over the last 5 years, P. cinnamomi was the most widely isolated and destructive species (1). Recently, a different species of Phytophthora was isolated from diseased roots and soil from around lateral roots of 10 declining trees in two orchards in the Veneto Region of northern Italy. Another species of Phytophthora was isolated consistently from rotted roots of declining walnut trees in two orchards in the Campania Region of southern Italy. Phytophthora spp. were isolated directly from plant material or Rhododendron spp. leaf baiting on soil samples with PARBhy selective medium (10 mg of pimaricin, 250 mg of ampicillin [sodium salt], 10 mg of rifampicin, 50 mg of hymexazol, 15 mg of benomyl, 15 g of malt extract, 20 g of agar in 1,000 ml of H₂O). Two species of Phytophthora were identified based on morphological and cultural characteristics (2). The species from trees in the Veneto Region was identified as P. nicotianae. All isolates produced papillate, spherical to obturbinate, occasionally caducous sporangia with short pedicels, terminal and intercalary chlamydospores, and were mating type A2. The species isolated from trees in the Campania Region was identified as P.citricola. Isolates were homothallic, produced semipapillate, persistent, obclavate to obpyriform sporangia, occasionally with two apices, and antheridia paragynous. Identifications were confirmed by comparing restriction fragment length polymorphism patterns of the internal transcribed spacer region of rDNA with those obtained from previously identified species of Phytophthora. Pathogenicity of two isolates each of P. citricola and P. nicotianae was tested on 2-year-old potted walnut seedlings. Inocula were prepared by inoculating sterilized millet seeds moistened with V8 broth with plugs of mycelium and incubated for 4 weeks at 20°C in the dark. Infested seeds were added to potting soil at a rate of 3% (wt/vol). One day later, pots were flooded for 48 h to promote sporulation. Ten noninoculated seedlings were used as the control. Symptoms were assessed 2 months after inoculation. Seedlings inoculated with P. nicotianae developed necrosis of feeder and lateral roots, but only limited infection of taproots. Seedlings inoculated with P. citricola developed necroses at the insertion points of lateral roots. All four isolates produced visible damage to lateral roots on inoculated plants. P. nicotianae and P. citricola were reisolated from respectively infected roots. Results from these inoculations confirmed P. nicotianae and P. citricola as root pathogens of English walnut. Both species were associated with walnut decline as reported in the United States (3). To our knowledge, this is the first report of P. nicotianae and P. citricola on J. regia in Europe. References: (1) A. Belisario et al. Petria 11:149. (2) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (3) M. E. Matheron and S. M. Mircetich. Phytopathology 75:977, 1985. (4) A. M. Vettraino et al. Plant Dis. 86:328, 2002.

First Report of Wilt and Dieback on Pokeweed (Phytolacca decandra) Caused by Phytophthora nicotianae

Pokeweed (Phytolacca decandra, synonym Phytolacca americana) is a root perennial plant that produces a succulent annual stem. In late June 2001, a severe dieback occurred on a group of pokeweed plants being grown as ornamentals in a garden in Rome. Disease symptoms consisted of leaf wilting followed by collapse of the plant. Stem collars and roots had dark brown-to-black water-soaked lesions. A wet rot was observed on plants with advanced disease symptoms. Isolations, from sections of roots and stems previously washed in running tap water, were made on PARBhy selective medium (10 mg of pimaricin, 250 mg of ampicillin [sodium salt], 10 mg of rifampicin, 50 mg of hymexazol, 15 mg of benomyl, 15 g of malt extract, and 20 g of agar in 1,000 ml of H2O) (2), followed by incubation at 20°C. A species of Phytophthora identified based on morphological and cultural characteristics (1) was isolated consistently from rotted roots and collars of diseased plants. All isolates produced papillate, spherical, ovoid to obturbinate, noncaducous sporangia and terminal and intercalary chlamydospores. Hyphal swellings with hyphal outgrowths were present. Observed characteristics were similar to those described for P. nicotianae. Isolates were mating type A2 with amphigynous antheridia in paired cultures with the A1 tester isolate of P. nicotianae. Identification was confirmed by comparing restriction fragment length polymorphism patterns of the internal transcribed spacer region of ribosomal DNA with those obtained from previously identified Phytophthora species. Pathogenicity tests were conducted on 10 2-month-old potted pokeweed plants. Inoculum was prepared by inoculating sterilized millet seeds moistened with V8 broth with plugs of mycelium and growing for 4 weeks. The inoculum was added to potting soil at 3% (wt/vol), and sporulation was induced by flooding the soil for 48 h. Five uninoculated plants were used as controls. Plants were maintained outdoors and assessed for symptoms within 2 months after inoculation. Wilting, root rot, and dark brown lesions on the collar developed on inoculated plants. The pathogen was reisolated from the inoculated plants and morphologically identical to the original isolates, which confirmed P. nicotianae as the causal agent of the disease. Few diseases have been reported on Phytolacca decandra. This species is not only an invasive weed, but is also cultivated as an ornamental and medicinal plant. In addition, antiviral (PAP) and antifungal (Pa-AFP) proteins that are used as a remedy for several human and plant infections have been extracted from the plant. To our knowledge, this is the first report of P. nicotianae on pokeweed. References: (1) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (2) A. M.Vettraino et al. Plant Pathol. 50:90, 2001.

Resistance to Fusarium oxysporum f. sp. melonis Race 1,2 in Muskmelon Lines Nad-1 and Nad-2

Of seven doubled-haploid melon lines parthenogenetically originated using irradiated pollen, two lines, Nad-1 and Nad-2, were selected for resistance to Fusarium wilt after successive inoculations with F. oxysporum f. sp. melonis race 1,2w virulent isolate. Nad-1 and Nad-2 were compared with the commercial hybrids and with the parent cvs. Isabelle and Giallo di Paceco. Evaluation of germplasm extended over a 2-year period showed a higher resistance of Nad-1 and Nad-2 plants to Fusarium oxysporum f. sp. melonis race 1,2 than other genotypes tested in this study. The resistance expressed in the two doubled-haploid lines could be due to their homozygous state that maximizes the expression of the genes for resistance already present in the parental line Isabelle. The use of this source of resistance may be exploited commercially either in rootstocks or to facilitate breeding for F1 hybrids. Future research will concentrate on the identification of genetic markers associated with resistance to race 1,2 using these doubledhaploid lines.

Occurrence and Etiology of Brown Apical Necrosis on Persian (English) Walnut Fruit

In 1998, a severe fruit drop was observed in Italy, principally on cv. Lara Persian (English) walnut (Juglans regia). Dropped fruit showed a brown patch at the blossom end and blackening and rot of inner tissues. The disease, called brown apical necrosis (BAN), was investigated on fruit collected in Italy and France in 1999. In 2000, studies were carried out in three walnut orchards located in Italy and in France to substantiate the etiology of BAN. Isolations performed from inner diseased fruit tissues yielded several fungi, in decreasing frequency of isolation: species of Fusarium and Alternaria, and one species each of Cladosporium, Colletotrichum, and Phomopsis. However, only Fusarium spp. were recovered from stigmas of BAN-affected fruit. The fungi associated with BAN-diseased fruit and species composition differed among locations and over time, confirming results obtained in previous investigations. The species of Fusarium used in pathogenicity tests reproduced BAN-disease symptoms when inoculated on fruit, whereas an Alternaria alternata isolate caused only limited necrosis of the style. However, the role of the other fungi commonly isolated from BAN-diseased fruit remains to be defined. The walnut blight pathogen, Xanthomonas arboricola pv. juglandis, occasionally was isolated from BAN-diseased fruit. No correlation was found between the extent of external brown patches and the size of inner lesions. Repeated isolations from and inoculations of fruit demonstrated that BAN can be considered a complex disease, and the inner infections originate from the style of the fruit.

First Report of Phytophthora cryptogea in Walnut Stands in Italy

English (Persian) walnut (Juglans regia L.) is among the most widely cultivated species in pure and mixed plantations of broadleaved trees in Italy. A decline of walnut of increasing occurrence has been reported recently in new plantations in central and northern Italy. Symptoms of the decline were typically characterized by yellowing of the foliage, defoliation, and plant death. Dark, flame-shaped necroses were often present at the collar. Phytophthora cactorum, P. cambivora, and P. cinnamomi were among the species associated with necrotic tissues of the collar and main roots (1). Furthermore, a Phytophthora sp. was isolated from soil removed from the lateral root zone of 6 of 15 declining trees in 3 walnut plantations, 2 in northern Italy and 1 in central Italy. Isolations were made by baiting with Rhododendron leaves and plating on PARBhy selective medium (3). The species isolated was identified as P. cryptogea on the basis of morphological and cultural characteristics (2). All isolates produced oval to obpyriform, nonpapillate sporangia and were mating type A2. Identification of the isolates was confirmed by comparing the restriction fragment length polymorphism patterns of the internal transcribed spacer region of ribosomal DNA with those obtained from previously identified Phytophthora species. Pathogenicity tests on potted 2-year-old walnut seedlings were conducted using two isolates of P. cryptogea. Inoculum was prepared by growing isolates on sterilized millet seeds added to soil at 2.5% (wt/vol). Sporulation was induced by 24-h flooding of the soil. Symptoms were assessed 1 month after inoculation. Ten uninoculated seedlings were used as controls. Inoculated seedlings showed no symptoms on the tap root, but there were extensive necroses of lateral roots ranging from 14 to 75% (average 38.6 ± 6.7 SE) of total lateral root (dry weight) compared with values of 0 to 11% (average 3 ± 1.5 SE) for uninoculated seedlings. P. cryptogea was easily reisolated from infected lateral roots and from the soil of inoculated pots. The inoculation trials confirmed P. cryptogea as a feeder-root pathogen of walnut in Italy. To our knowledge, this is the first report of P. cryptogea on English walnut in Italy. This species often has been associated with walnut decline in the United States (2) and on other woody plants in Italy (3). References: (1) A. Belisario et al. Petria 11:127, 2001. (2) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Association, St. Paul, MN, 1996. (3) A. M. Vettraino et al. Plant Pathol. 50:90, 2001.

[Bronchial hyperreactivity to methacholine in a group of bakers sensitized to wheat flour]

BACKGROUND

Bakers' allergic diseases are a well known occurrence. Wheat flour is the most important allergen responsible for rhinoconjunctivitis and IgE mediated asthma. The good correlation between atopy, wheat flour sensitization and allergic diseases is also well known. In a previous study we described the results concerning sensitivity to wheat flour in a group of 300 bakers, followed up for 8 years. In this study we showed that the same subjects who were sensitive to wheat flour had no symptoms.

AIM

The aim of this study was to carry out the metacholine test for bronchial hyperreactivity in a group of 14 bakers selected from the group of 300 previously studied.

METHODS

The subjects underwent: pulmonary function test, IgE test, skin prick test with grass pollen, Dermatophagoides farinae, Dermatophagoides pteronissinus, wheat flour, and the metacholine test.

RESULTS

The results of the metacholine test showed only one positive case in a subject with positive skin prick test. This agreed with the assumptions of our previous study that showed a sensitization (10%) to wheat flour but a low prevalence of allergic symptoms.

CONCLUSIONS

Limited to the subjects studied, the results indicate an absence of a relationship between positive prick tests and aspecific bronchial hyperreactivity. Recent research that suggest a probable different genetic control of atopy, bronchial hyperreactivity and asthma is discussed. In our opinion effective primary and secondary prevention could account for this absence of relationship.

[Four-year follow-up of a group of workers with allergic sensitization employed in breeding of insects for biological pest control]

In two previous papers we reported allergic diseases in workers employed in breeding insects for biological pest control. It was found that Ephestia kuehniella, Orius laevigatus and other insects caused allergic rhinoconjunctivitis and asthma. The aim of this new study was to assess the relationship between the implementation of the recommended preventive measures and the decrease in sensitization in exposed workers. We performed a four-year follow-up of exposed workers, using the prick test and RAST with specific allergens and pulmonary function test at the end of the work shift. The results showed a decrease in skin test sensitization for Orius and Ephestia, a decrease in allergic diseases in the previously studied workers, and no symptoms in recently employed workers. These results confirm the validity of the recommended preventive measures: semi-closed cycles, gloves, protective masks, overalls and sunglasses.

First Report of Root and Collar Rot by Sclerotium rolfsii on Apple Trees in Italy

Sclerotium rolfsii Sacc. (teleomorph Athelia rolfsii (Curzi) Tu & Kimbrough) is a polyphagous, soilborne plant pathogen. In summer 1998, a sudden death of 2-year-old apple trees (Malus domestica Borkh.) cv. Royal Gala grafted on M9 rootstock was observed in an orchard near Rome, Italy. Symptoms were stunted vegetation, leaf chlorosis, and root and collar rot. A fungus identified as S. rolfsii was observed producing sclerotia and whitish mycelial strands on root and collar bark. Isolations from roots and at the margin of subcortical necrosis on the collar consistently yielded S. rolfsii colonies on potato dextrose agar (PDA); sclerotia developed within 7 days. Koch's postulates were fulfilled by inoculating 10 1-year-old apple tree cv. M9 rootstocks, grown in 3.5-liter pots, with an S. rolfsii isolate grown for 1 week on PDA at 25°C. One ground plate per plant was used, placed around collar and main roots. Five control plants were treated with PDA only. Rootstocks were kept in the greenhouse at 26 ± 2°C. Within 2 months, 70% of inoculated plants died, with marked necrosis girdling the collar. The other inoculated plants showed a general decline, with widespread necrosis on collars and main roots. Control plants remained healthy. S. rolfsii was reisolated from collars and roots of symptomatic plants. S. rolfsii has been recorded on apple trees in the U.S., India, China, and Israel. In Italy, it is destructive on several crops, and was recently recorded on walnut (1). This first outbreak of S. rolfsii on apple in Italy may have been favored by exceptionally warm late spring and summer temperatures. Reference: (1) A. Belisario and L. Corazza. Plant Dis. 80:824, 1996.

First Report of Alternaria alternata Causing Leaf Spot on English Walnut

A foliar disease of English walnut (Juglans regia L.) was observed in 1998 in an orchard in northern Italy. Symptoms consisted of circular, necrotic spots bordered with concentric zones of darker tissue. Average lesion diameter was 20 mm, although lesions could extend to half of the leaflet lamina. A fungus identified as Alternaria alternata (Fr.:Fr.) Keissl. (1) was observed on the necrotic tissue and was consistently isolated from the margins of the necrosis. Conidia from leaves were brown, ellipsoid to ovoid (primary conidia 28 to 60 × 8 to 15 μm; secondary conidia 10 to 30 × 7 to 13 μm), with walls often ornamented, 1 to 6 transversely septate and 0 to 3 longitudinally septate. For pathogenicity tests, three isolates were grown on potato dextrose agar for 2 weeks. Inoculations were performed on detached, surface-sterilized, healthy J. regia leaflets. Four drops (5 μl each) of a sterile water suspension of 1 × 10⁵ conidia per ml were placed on each leaflet; three leaves per isolate were used. Leaves were incubated in a moist chamber. After 10 days, leaf spots similar to the original symptoms developed on all the inoculated points for all three isolates, and the pathogen was reisolated. Control leaflets inoculated with sterile, distilled water remained symptomless. The experiment was performed three times and the results were similar. Alternaria alternata is a well-known pathogen on many crops but a few records report this fungus as a causal agent of leaf spot on deciduous trees. This is the first report of A. alternata on English walnut. Reference: (1) E. G. Simmons. Mycotaxon 37:79, 1990.

First Report of Myrothecium verrucaria from Muskmelon Seeds

Myrothecium verrucaria (Albertini & Schwein.) Ditmar:Fr. was isolated from muskmelon (Cucumis melo L.) seeds of Charentais-T, a culti var used as a differential host with no resistance to Fusarium oxysporum f. sp. melonis races. A white floccose mycelial mat developed on melon seeds during incubation on moist blotters. Mycelia were mass transferred from melon seeds onto potato dextrose agar (PDA) medium. At 25°C in the dark, a mycelial mat with characteristic annelations of greenish-black sporodochia, without setae, was produced. Conidia (2 to 3 × 6 to 10 μm) were lemon shaped, with a typical conical mucous appendage at one end, which was visible with Loeffer's flagella stain (1). Based on these characteristics, the fungus was identified as M. verrucaria. For pathogenicity studies, surface sterilized seeds of C. melo cv. Charentais-T were coated with M. verrucaria conidia by gently rubbing the seeds on sporodochia produced on 15-day-old cultures on PDA. Once coated, seeds were plated onto water agar and on sterile moist blotters in 9-cm-diameter petri dishes. Plates were incubated at 28°C in the dark. Five seeds per plate and three plates per experiment were used. Experiments were replicated three times. Control seeds were plated without coating. After 7 days, on water agar, 90% of melon seeds failed to germinate while the remaining 10% produced young seedlings that died from root rot and necrotic lesions on the hypocotyl. After 12 days on moist blotters, 100% of the melon seedlings died, showing necrotic lesions on the hypocotyl and on the main root. The pathogen was reisolated from symptomatic melon seedlings. All control seeds germinated and grew into healthy seedlings. M. verrucaria, known to be a seed-borne pathogen, has been isolated from soil and plants worldwide (2). This is the first report of M. verrucaria pathogen on muskmelon. This fungus is not a serious concern when seeds are dressed with fungicides. References: (1) K. V. A. Thompson and S. C. Simmens. Nature. 193:196, 1962. (2) S.-M. Yang and S. C. Jong. Plant Dis. 79:994, 1995.

[Occupational asthma caused by dioctyl-phthalate in a bottle cap production worker]

The authors describe a clinical case of occupational asthma due to dioctyl-phthalate in a worker using a conveyor belt for bottle stoppers. The dioctyl-phthalate is used for the production of PVC and as a compound of many other substances. The literature describes many cases of occupational asthma do to phthalate anhydride but few cases do to dioctyl phthalate. The clinical history, the environmental monitoring data, the pulmonary function tests such as bronchodilatation test by salbutamol, peak flow meter daily monitoring for three weeks, and stop and start work test showed a good correlation with the work and the worker's asthma. The authors emphasize that a detailed clinical history and a careful analysis of the production cycle are very useful and, as simple and non invasive tests, can play an important role in the diagnosis of occupational asthma.

Airborne contact dermatitis from 2-amino-2-methyl-1-propanol in a cosmetic company

The authors described two cases of airborne contact dermatitis caused by 2-amino-2-methyl-1-propanol (AMP 100) in two subjects with periorbital erythema and itching skin. The AMP 100 has been used to replace ammonia as a hair dye component in the cosmetic industry with the purpose to eliminate its smell. Patch tests proved positive only to dilutions of 10% and 20% in the two described patients, as well as in other six asymptomatic subjects operating in the same working environment. The authors have diagnosed an irritative airborne contact dermatitis by AMP 100.

[Sensitization and allergic pathology in a group of workers employed in insect breeding for biological pest control]

On the basis of the results of a previous study and immuno-allergological tests, a group of workers employed in breeding insects for biological pest control were studied to ascertain whether any new sensitizations to arthropods recently included in the work cycle occurred and whether any new allergic diseases were observed. The results confirmed a high sensitization to Ephestia kuehniella and to Orius, the latter probably due to contamination; sensitization to Tetranicus urticae and to Planococcus citri were observed, although to a lesser degree. It is concluded that the insects used in biological pest control are highly allergogenic and that the protective devices used up to the present were ineffective; the authors therefore recommend the use of closed or semi-closed cycles along with local ventilation equipment.

[Psychosomatic changes in video terminal operators]

The incidence of psychosomatic symptoms in a group of VDT operators is evaluated and compared with a control group (people not working at VDTs) by using questionnaires. The dta show that some psychosomatic symptoms are much more frequent in VDT operators in comparison with the control group.

[Ocular symptoms and video display terminals: study of a group of video-terminal operators]

Ocular symptoms have been evaluated on a VDT operators group, by using questionnaires and an ophthalmological screening. The results show that some ocular fatigue symptoms are much more frequent in VDT operators in comparison with the control group. VDT operators working more than 4 hours/day at VDT are the most affected.

[Evaluation of stress indicators in 2 groups of video display terminal operators]

The results of a study on 68 VDT operators are hereby presented. Various biochemical indexes are evaluated as markers of stress. In particular, urinary catecholamines and their metabolites (E, NE, DA, HVA, VMA), ACTH, cortisol, NEFA and fructosamine have been tested by the Authors. Each assay has been performed both in basal conditions, and after the completion of subjects workshift, taking into account the normal hormonal biorhythms. The data which emerged have been analyzed by statistical method ("Student t" with coupled data). Each subject data was confronted before and after workshift. The number of hours of VDT exposure and the different types of duties have been considered and evaluated. The results show that, although the data are all included within the normal range, some of the tested parameters after workshift are significantly higher, compared with the same parameters referring to the basal condition. In particular, Epinephrine and Norepinephrine seem to be the most effective markers of stress. Analogous studies will be pursued in the future by the Authors on a larger number of VDT operators.

[Pathology caused by video terminals: critical review]

A review of data resulting from the studies on health aspects of VDT operators is hereby presented and discussed by the Authors. In particular, researches on visual, musculoskeletal, dermatological and reproductive system alterations in VDT operators, together with psychological aspects, are evaluated and problems involved in radiation emission from VDTs are exposed too. Preventive measures are mentioned. According to the majority of the studies--up to now--no valid evidence of any abnormalities has been provided that can be specifically attributed to VDT work. The necessity of further researches on psycho-organic aspects of work with VDT is suggested by the Authors.

[Work with video display terminals: evaluation of psychosomatic aspects in a group of VDT operators]

The prevalence of psychosomatic symptoms in a group of VDT telephone operators is evaluated and compared with a control group (people not working at VTDs), by using questionnaires. The results show that psychosomatic symptoms are much more frequent in VDT operators in comparison with the control group.

[Ocular fatigue syndrome in subjects exposed to video display terminals: definition and evaluation in a group of VDT operators]

The incidence of the "ocular fatigue syndrome" in a group of VDT telephone operators is evaluated and compared with a control group (people not working at VDT), by using questionnaires. The results show that the "ocular fatigue syndrome" is much more frequent in VDT operators in comparison with the control group.

[Round shadow in the lung of an unusual origin: chronic pneumonitis caused by occupational exposure to synthetic fibers]

A case of granulomatous pneumonia due to synthetic fibres was observed; no specific symptoms, blood patterns, radiographic findings were found. Some clinical considerations on this unusual syndrome are reported.

[Therapy of spontaneous pneumothorax. Results of 20 years' experience]

256 spontaneous pneumothorax episodes in 165 patients were treated during the period 1956-1978. Continuous aspiration with drainage of the pleural cavity was employed in 156 cases, and parietal pleurectomy for 36 recurrent or undrainable cases. One patient in the latter group underwent bilateral parietal pleurectomy. The soundness of aspirative drainage on the occasion of the first episode is underscored by the low percentage of recurrences. The indications for pleurectomy are discussed. Its effectiveness is apparent from the good functional results it offers, in addition to an absence of relapses.