First Report of Shoot Blight of Grapevine Caused by Sclerotinia sclerotiorum in Illes Balears, Mallorca, Spain

In 2021, grapevines (Vitis vinifera L.) cv. Callet growing in a commercial vineyard located at Pollença (northeast of the island of Majorca, Spain) showed severe symptoms of shoot blight during spring and early summer, with an incidence of 70%. Symptoms consisted of elongated cankered-like lesions, surrounded by water-soaked darker tissues, that developed at the base or around the middle nodes of the shoot. For fungal isolation, shoot samples with lesions were collected, surface disinfected with 2% NaCl for 90s, rinsed twice with deionized water and placed in Petri plates containing potato dextrose agar (PDA). The plates were incubated at 25°C under 12 h light-darkness for 6 days. Isolations consistently yielded on kind of fungal colonies that produced white mycelium and black spherical to elongated sclerotia (2 to 10 mm in diameter). Morphological characterization was consistent with the description of Sclerotinia sclerotiorum (Lib.) de Bary (Bolton et al. 2006). Three isolates (UIB 118-1, UIB 118-26, and UIB 129-41) were preserved and deposited in the Culture Collection of Microbiology-Faculty of Sciences, University of Balearic Islands, Spain. Genomic DNA was extracted from isolates UIB 118-26 and UIB 129-41 using the EZNA Miniprep Kit (Omega Bio-Tek, Norcross, GA). The internal transcribed spacer (ITS) region of ribosomal DNA, β-tubulin (BTUB) and calmodulin (CAL) gene regions were amplified using ITS1F-ITS4 (Gardes and Bruns, 1996; White et al. 1990), Bt-2a/Bt-2b (Glass and Donaldson 1995) and CAL228F/CAL737R (Carbone and Kohn 1999) primer sets, respectively. Amplicons were sequenced and deposited in GenBank with accession numbers MZ604647 and MZ604648 for ITS, OK634402 and OK634403 for BTUB and OK634404 and OK634405 for CAL. BLASTn search showed that isolates were >99 % (ITS, BTUB and CAL) identical to S. sclerotiorum GenBank accession no. KF859933, CP017815 and KF871381, respectively. Pathogenicity tests were conducted using eight one-year old grapevines cv. Cabernet Sauvignon. Old and new green shoots were inoculated by inserting a 6-mm plug of mycelium taken from actively growing cultures on PDA into cuts made at the base and at the distal part of each shoot with a sterile scalpel with a total of eight inoculation points per plant. Inoculated wounds were sealed with Parafilm tape to avoid rapid dehydration. Inoculated plants and an equal number of wounded but non-inoculated plants (negative controls) were maintained at 25 ± 1°C for 48 h in plastic containers to ensure a high relative humidity (>90%). After 5 days, the infection girdled and rotted the green new shoots, whereas the older partially lignified shoots developed a localized long brown lesion that reached 16 cm in length. Due to the rotting of the basal part of the petiole, leaves turned gray, wilted, and died, easily detaching from the stem. In advanced stages of the disease, 7 days after infection, branches died and fell with the leaves remained attached (Fig 1 A, B). Reisolations from diseased shoots were successfully performed on PDA to fulfill Koch's postulates. S. slerotiorum was previously reported on grapevine causing shoot blight in Chile (Latorre and Guerrero, 2001), Korea (Jong-Han et al. 2009), California-USA (Boland and Hall, 1994) and Australia (Hall et al. 2002). AlsoS. sclerotiorum was reported among the endophytic mycobiota associated with Vitis vinifera in the Iberian Peninsula (Gonzalez and Tello, 2011) but not as a pathogen causing visible symptoms on that crop. So, this is the first report of the occurrence of S. slerotiorum as a pathogen of grapevines in Spain causing symptoms of canker and shoot blight. This finding highlights a potential risk of this fungal disease for the wine industry in the Mediterranean region and specially for Spain, the country with the largest acreage devoted to grapevines. Although chemical and biological are suitable control strategies, disease management is difficult as sclerotia of Sclerotinia can remain in the soil for up to eight years (Adams and Ayears, 1979), and preventive surveys are greatly recommended as an important epidemiological tool to monitor the epidemiology of disease and identify potential outbreaks of this new pathogen on grapevine in Spain.

Lasiodiplodia regiae sp. nov.: A New Species Causing Canker and Dieback of Fruit Trees in China

Canker and dieback are serious fungal diseases of woody plants that can cause huge economic losses to orchards. The purpose of this study was to classify and assess the pathogenicity of fungal species associated with canker and dieback on fruit trees growing in Henan Province, China. In total, 150 isolates of Botryosphaeriaceae were obtained from six different fruit trees exhibiting typical symptoms of stem canker, branch dieback, and gummosis. Morphological examinations and phylogenetic analysis of ITS, tef1, tub2, and rpb2 revealed two Botryosphaeriaceae species, which are Botryosphaeria dothidea and a novel species, Lasiodiplodia regiae, respectively. Using Koch's postulates, we confirmed that the different isolates of L. regiae can cause disease in their original hosts. The pathogenicity tests showed that L. regiae can cause canker, dieback, and gummosis symptoms in four different hosts, indicating a relatively wider host range. Moreover, 10 L. regiae isolates exhibited similar symptoms but different levels of virulence on shoots of peach trees under field conditions. This study demonstrated that L. regiae was a new causal agent of canker and dieback of six fruit tree species, which could be a serious risk to the orchard industry in China. Furthermore, the findings provide a foundation for further epidemiological studies and the development of management strategies.

Genetic Diversity and Fungicide Sensitivity of Cytospora plurivora on Peach

Cytospora plurivora D.P. Lawr., L.A. Holland & Trouillas has been associated with recent premature peach tree decline in South Carolina, but very little is known about the pathogen or chemical control options. Ninety-three C. plurivora isolates were collected in 2016 and 2017 from 1-year-old peach wood and symptomatic scaffold limbs, respectively, from orchards in six towns in South Carolina. Six unique genotypes were identified based on substantial ITS1-5.8S-ITS2 sequence variability and classified G1 to G6. Three of the genotypes (G2, G3, and G6) were isolated in high frequency in multiple locations of both years. In addition to the genotypic variation, multiple phenotypes were observed between and within genotype groups. Species identity was determined using additional gene loci: ACT, TUB, and EF, and isolates were found to belong to C. plurivora for all genotype groups. All tested genotypes were sensitive to thiophanate-methyl (FRAC 1) but exhibited slightly lower sensitivity to propiconazole and difenoconazole (both FRAC 3). Boscalid, fluopyram (both FRAC 7s), azoxystrobin, and pyraclostrobin (both FRAC 11s) were ineffective in vitro at inhibiting mycelial growth of C. plurivora genotypes. Field inoculation of peach and nectarine trees revealed that all genotypes developed twig cankers with differences in virulence. G1 was most virulent, and G6 was least virulent. This study provides a link between the C. plurivora genetic variability and virulence and provides fungicide sensitivity information that could be used to improve disease management practices.

First report of Neopestalotiopsis sp. causing trunk disease on European chestnut in Spain

In April 2021, a brownish-brown vascular lesion was observed in the stemwood of a five-year-old chestnut (Castanea sativa Mill.) rootstock when cutting for grafting in Villaviciosa (Asturias, Northern Spain). To identify the causal agent, a cross section of the steam was cut, surface-sterilized with 96% ethanol and dried, plated on potato dextrose agar (PDA) and incubated at 25ºC. Fungal colonies were consistently isolated and after 5 days developed abundant greyish-white mycelium. For molecular identification, the internal transcribed spacer (ITS) gene region of rDNA of the strain LPPAF-975 was amplified with the ITS1/ITS4 primers (White et al. 1990) using the TerraTM PCR Direct Polymerase Mix (Takara Bio Company, CA, USA). This sequence was deposited in GenBank (accession no: OR002144) and showed 99.80% identity over a 507 pb alignment with the Neopestalotiopsis isolate 328-16 (accession no: OK166668) isolated on blueberry in Serbia and Nespestalotiopsis australis strains LNZH0701 and LNZH0752 (accession nos: OM919511-12) both isolated on blueberry in China. To clarify the identification, beta-tubulin (tub2) and translation elongation factor alpha-1 (tef1-a) were amplified (Glass & Donaldson 1995, Walker et al. 2010, respectively). Beta-tubulin sequence (accession no: OR001747) was 99.52% of identity with sequences of several species of Neopestalotiopsis, and elongation factor (accession no: OR001748) was 99.57% identity with sequences previously deposited for N. clavispora (accession nos: OP684010-11, MZ097377-79). The phylogenetic tree was constructed with the three concatenated sequences using the Maximum Likelihood method based on the Tamura-Nei model (Tamura and Nei, 1993), and their topological robustness was evaluated by bootstrap analysis based on 1,000 replicates using Mega 11 (Tamura et al, 2021). However, strain LPPAF-975 clustered with N. javaensis, N. rosae and N. vacciniicola, therefore the species remains unidentified. Pathogenicity tests were carried out on ten five-year-old chestnut plants on which a half 5-mm-diameter PDA plug from the edge of an actively growing colony of the fungus was inoculated by a cut in the bark of one to three branches per plant and then wrapped with Parafilm©. Five plants inoculated as above but without the fungus were used as controls. Plants were cultivated in pots provided with drip irrigation in a tunnel under natural conditions. The assay was conducted twice. External cankers around the inoculated area were observed a month after inoculation, while control plants did not show any lesions. The fungus was re-isolated on all the inoculated plants, but not from controls. As all the re-isolated strains had the same morphology, one of them was randomly selected and identified by sequencing, thus fulfilling Koch's postulates. Cross-sections of plants showed lesions similar to that initially found, with 100% of the plants damaged at the point of inoculation, and 80 and 65% 1 cm above and below, respectively. Pathogen was newly re-isolated and identified from one of these cross-sections. To the best of our knowledge, this is the first report worldwide of Neopestalotiopsis sp. causing disease on Castanea sativa. This pathogen could represent a threat to the maintenance of the biodiversity of traditional chestnut varieties, multiplied by grafting on rootstocks in nurseries, which would incur considerable economic losses.

First Report of Olive Branch Dieback in Croatia Caused by Cytospora pruinosa Défago

Olive (Olea europaea L.) is a very important crop grown in the Mediterranean part of Croatia. Olive branch and fruit dieback symptoms were observed in two olive orchards in Istria, Croatia. The samples from symptomatic trees were collected and brought to the laboratory for analysis. Based on their morphological characterization, isolated fungi were identified as Cytospora sp. Two representative isolates (one per orchard) were taken for molecular analysis, and based on DNA sequence data of the ITS and TUB gene regions, and phylogenetic analysis of the sequences, the isolates were identified as Cytospora pruinosa Défago. To determine pathogenicity, pathogenicity tests were conducted on detached olive branches and two-year-old olive trees in the greenhouse. This is the first report of C. pruinosa causing olive branch and fruit dieback in Croatia.

First Report of Cytospora azerbaijanica Causing Cytospora Canker and Shoot Dieback on Peach (Prunus persica) in California, U.S.A

Peaches (Prunus persica L.) are an important crop in the United States with California leading the nation in peach production, with approximately 505,000 tons valued at $378.3 million (USDA National Agricultural Statistics Service, 2021, https://www.nass.usda.gov/). From April to July 2022, symptoms of branch and scaffold canker as well as shoot dieback were observed in three peach (cvs. Loadel, Late Ross and Starn) orchards located in San Joaquin County, California. Samples were collected from about 12 trees for each cultivar. Fast-growing, white, flat colonies were consistently isolated from active cankers on acidified potato dextrose agar (APDA) following the method described by (Lawrence et al. 2017). Pure fungal cultures were obtained by transferring single hyphal tips onto new APDA Petri plates. A total of 22 isolates were obtained. Each fungal isolate was recovered from a single diseased branch (40 to 55% recovery). All isolates in this study shared similar morphological characteristics. Fungal colonies were fast-growing with relatively even but slightly dentate margin, flat with white to off-white mycelium that turned vinaceous buff to pale greyish sepia (Rayner 1970) with age. Black, globose, ostiolated pycnidia, 0.8-(1.3)-2.2 mm diameter, with brownish surface hyphae formed on peach wood embedded in PDA after approximately three weeks and exudated buff-colored mucilage. Pycnidia were both solitary and aggregated and had multiple internal locules sharing invaginated walls. Conidiogenous cells were hyaline, smooth-walled, septate, tapering towards the apex, 13-(18.2)-25.1 × 0.8-(1.3)-1.9 µm (n = 40). Conidia were hyaline, allantoid, smooth, aseptate, 5.5-(6.3)-7.1 × 1.4-(1.9)-2.3 µm (n = 40). Genomic DNA was extracted and sequences of the internal transcribed spacer region (ITS) using ITS5/ITS4 universal primers, translation elongation factor 1α gene (TEF) using primers EF1-728F/EF1-986R, second largest subunit of RNA polymerase II (RPB2) using primers RPB2-5F2/fRPB2-7cR, and actin gene region (ACT) using primers ACT-512F/ACT-783R were obtained and compared with sequences available in GenBank (Lawrence et al. 2018; Hanifeh et al. 2022). Isolates were identified as Cytospora azerbaijanica following DNA sequencing and morphological identification. Consensus sequences of the four genes of two representative isolates (SJC-66 and SJC-69) were deposited into GenBank database (ITS: OQ060581 and OQ060582; ACT: OQ082292, OQ082295; TEF: OQ082290 and OQ082293; RPB2: OQ082291 and OQ082294). The Basic Local Alignment Search Tool (BLAST) indicated that the sequenced RPB2 genes of isolates (SJC-66 and SJC-69) were at least 99% identical to that of Cytospora sp. strain shd47 (Accession: MW824360) covering at least 85% of the sequences. The actin genes from our isolates were at least 97.85% identical to that of Cytospora sp. strain shd47 (Accession: MZ014513), covering 100% of the sequences. The translation elongation factor gene from isolates (SJC-66 and SJC-69) was at least 96.4% identical to that of Cytospora sp. strain shd166 (Accession: OM372512), covering 100% of the query. Those top hit strains belong to C. azerbaijanica, recently reported by Hanifeh et al. (2022). Pathogenicity tests were performed by inoculating eight wounded, 2- to 3-year-old healthy branches on each of eight 7-year-old peach trees, cvs. Loadel, Late Ross and Starn, using 5-mm-diameter mycelium plugs collected from the margin of an actively growing fungal colony on APDA. Controls were mock-inoculated with sterile agar plugs. Inoculation sites were covered with petroleum jelly and wrapped with Parafilm to keep moisture. The experiment was performed twice. After four months, inoculation tests resulted in vascular discoloration (canker) above and below the inoculation sites (average necrosis length of 114.1 mm). Cytospora azerbaijanica was re-isolated from all infected branches (70 to 100% recovery) completing Koch's postulates. Controls remained symptomless and no fungi were isolated from the slightly discolored tissue. Cytospora species are destructive canker and dieback pathogens of numerous woody hosts worldwide. Recently, C. azerbaijanica was reported in causing canker disease of apple trees in Iran (Hanifeh et al. 2022). To our knowledge, this is the first report of C. azerbaijanica causing canker and shoot dieback of peach trees in the United States and worldwide. These findings will aid towards a better understanding of genetic diversity and host range of C. azerbaijanica.

Validation of an Alternative Small Stem Assay for Blight Resistance in Chestnut Seedlings and Recommendations for Broader Use

We evaluated an alternative small stem assay (AltSSA) for blight resistance in backcross hybrid chestnut trees (Castanea dentata/mollissima). Whereas standard small stem assays (SSAs) are done by inoculating small incisions in stems, in our AltSSA, 4- to 5-mm stems are cut off, and the exposed (living) stem tips are inoculated with discs of Cryphonectria parasitica inoculum and temporarily covered with plastic sleeves. Intended primarily for forward selection, this method was designed to be easy to implement, to consistently induce cankering, and to better enable seedling recovery via the development of lateral shoots from the lower stem. After 90+ days, cankers are evaluated and removed, and seedlings are prepared for out-planting. Previous results showed that AltSSAs performed at least as well as a common SSA method in distinguishing resistant and susceptible types. In this follow-up analysis of 35 lines of backcross seedlings studied in 2020 and 2021, we showed that mean orange zone canker length (OZCL) and a multifactor principal components analysis-based blight resistance index gave results consistent with predictions derived from two methods of blight resistance phenotyping and percentage of American chestnut ancestry of the parents of each line. As expected, based upon the apparent polygenic inheritance of blight resistance in backcross chestnut trees, mean OZCL of backcross families ranged from intermediate (F₁ hybrid-level) to low (wild-type American chestnut-level). Consistent with prior results, canker production was near 100%, survivorship after out-planting was very high, and postinoculation stem dieback was not apparently related to the stem tip inoculations. Altogether, these results suggest that the AltSSA is a viable method for early detection of relative blight resistance in seedlings and may enable a reduction in the numbers of trees out-planted and placed under care for long-term evaluation and breeding. Thus, the AltSSA can prevent time, resources, and orchard space from being used on susceptible trees.

A New Species of Neoscytalidium hylocereum sp. nov. Causing Canker on Red-Fleshed Dragon Fruit (Hylocereus polyrhizus) in Southern Thailand

During 2020-2021, cultivated red-fleshed dragon fruit (Hylocereus polyrhizus) in Phatthalung province, southern Thailand, was infected with canker disease in all stages of growth. Small, circular, sunken, orange cankers first developed on the cladodes of H. polyrhizus and later expanded and became gray scabs with masses of pycnidia. The fungi were isolated using the tissue transplanting method and identified based on the growth of the fungal colony, and the dimensions of the conidia were measured. Their species level was confirmed with the molecular study of multiple DNA sequences, and their pathogenicity was tested using the agar plug method. Morphological characterization and molecular identification of the internal transcribed spacer (ITS), translation elongation factor 1-α (tef1-α) and β-tubulin (tub) sequences revealed the fungal pathogen to be a new species. It was named Neoscytalidium hylocereum sp. nov. The biota of the new species, N. hylocereum, was deposited in Mycobank, and the species was assigned accession number 838004. The pathogenicity test was performed to fulfil Koch's postulates. N. hylocereum showed sunken orange cankers with a mass of conidia similar to those observed in the field. To our knowledge, this is the first report of H. polyrhizus as a host of the new species N. hylocereum causing stem cankers in Thailand.

Re-evaluation of the Fungal Diversity and Pathogenicity of Cytospora Species from Populus in China

Poplar is widely cultivated in China because of its strong ecological adaptability, fast growth, easy reproduction, and short rotation period. However, it suffers from severe threat from canker disease caused by Cytospora species. The present study revealed the presence of Cytospora species from Populus in China. A total of six species of Cytospora were isolated from Populus in six provinces in China, including five known species (C. ailanthicola, C. chrysosperma, C. donglingensis, C. paratranslucens, and C. sophoriopsis) and one novel species (C. populi) based on morphological and phylogenetic analyses of ITS, act, rpb2, tef1-α, and tub2 gene sequences. Cytospora ailanthicola, C. chrysosperma, C. paratranslucens, and C. sophoriopsis are confirmed as pathogens by pathogenicity tests of which C. paratranslucens showed the strongest virulence, followed by C. ailanthicola, C. chrysosperma, and C. sophoriopsis. The mycelial growth rates of isolates from the six species had 22.5 to 27°C as the optimum temperatures, and the optimum pH values were 5.9 to 7.1. The effectiveness of six carbon sources on the mycelial growth showed that colonies grew the fastest in the presence of fructose and grew the slowest using xylose. This study represents a significant evaluation of Cytospora causing poplar canker disease in China.

First report of Neofusicoccum australe causing dieback of honeybush in the Western Cape, South Africa

Honeybush (Cyclopia spp.) is an indigenous, leguminous member of the Cape fynbos biome growing in the coastal winter rainfall districts of the Western and Eastern Cape Provinces of South Africa (Joubert et al. 2011). Honeybush is used for the production of herbal teas and is harvested from wild-growing and cultivated plantations (du Toit et al. 1998). Very little is known regarding diseases caused by pathogens on this indigenous plant. Only one report of twig dieback on honeybush caused by several Diaporthe Nitschke species have been reported in South Africa (Smit et al. 2021). Several honeybush producers reported poor growth and dieback in their C. subternata plantations in the Western Cape Province, South Africa. Symptoms included twig dieback, branch dieback, death of branches as well as death of entire plants. In April 2008, branches from 8-year-old cultivated plants with dieback symptoms were collected in Stellenbosch. Fungal isolations were carried out from affected material as described by Van Niekerk et al. (2004) which consistently revealed the presence of a Botryosphaeriaceae species. Two isolates were grown on water agar with sterile pine needles and incubated at 25˚C using a 12-hour day/night cycle and near-ultraviolet light. Pycnidia formed after two weeks. Morphological characteristics similar to Neofusicoccum australe (Slippers, Crous & Wingfield) Crous, Slippers & Phillips were observed (Phillips et al. 2013). Conidia were hyaline, aseptate, fusiform with subtruncate bases (16.8-)18.8-22.1(-24.6) × (4.8-)5.3-6.1(-6.4) µm (n=50). Conidiogenous cells were holoblastic, hyaline and subcylindrical to flask-shaped tapering to the apex (11-15 × 2 µm) (n=10). Colonies on potato dextrose agar were light primrose turning olivaceous grey after 7 days with a light-yellow pigment diffusing into the medium. Mycelia was moderately dense with an appressed centre mat. The identity of the isolates was further confirmed by sequencing the ribosomal RNA Internal Transcribed Spacer (ITS) and the elongation factor 1-alpha (EF-1α) gene regions using primer pairs ITS4-ITS5 (White et al. 1990) and EF1-728F-EF1-986R (Alves et al. 2008), respectively. Sequences had a 100% similarity to N. australe ex-type CMW6837 isolate (accessions AY339262 and AY339270) (Slippers et al. 2004). Two isolates (STEU6554 and STEU6557) were deposited in the culture collection at the Department of Plant Pathology at Stellenbosch University and the sequences were submitted to GenBank with accession numbers ON745603, ON745604, ON746573 and ON746574. Pathogenicity tests using the two N. australe isolates were conducted by inoculating two shoots each of three field-grown C. subternata plants with a 4mm colonised potato dextrose agar (PDA) mycelium plug of each isolate on wounds made by a 4mm cork borer (Van Niekerk et al. 2004). A third shoot was inoculated with a uncolonized PDA plug as the negative control. After 12 weeks, brown-black lesions that were significantly longer (average 55.2 mm) than the uncolonized agar plug control (16.1 mm) were observed. Lesions were observed in all three plants. Neofusicoccum australe was re-isolated (van Niekerk et al. 2004) from all inoculated shoots confirming Koch's postulates. The economic impact and damages caused by N. australe as well as its incidence and severity on honeybush in South Africa is unknown. However, the pathogen caused dieback of entire branches and death of plants indicating that it could be an important pathogen of honeybush. Additionally, N. australe is one of the most important disease-causing Botryosphaeriaceae pathogens on a wide range of economical fruit and vine crops globally (Mojeremane et al. 2020). This is the first report of N. australe as a known pathogen causing decline and dieback of C. subternata in South Africa. References: Alves, A. et al. 2008. Fungal Divers. 28:1. du Toit, J. et al. 1998. J. Sustain. Agric. 12:67. Joubert, E. et al. 2011. S. Afr. J. Bot. 77:887. Mojeremane, K. et al. 2020. Phytopathol. Mediterr. 59:581. Phillips, A. J. et al. 2013. Stud. Mycol. 76:51. Slippers, B. et al. 2004. Mycologia 96:1030. Smit, L. et al. 2021. Eur. J. Plant Pathol. 161:565. van Niekerk, J. M. et al. 2004. Mycologia 96:781. White, T. J. et al. 1990. Pages 315 in: In PCR Protocols: A Guide to Methods and Applications. Academic Press Inc, USA. Declaration. The author(s) declare no conflict of interest Acknowledgments. This work benefitted from the financial support of the Agricultural Research Council, Infruitec-Nietvoorbij, South Africa.

Diseases Severity, Genetic Variation, and Pathogenicity of Ceratocystis Wilt on Lansium domesticum in South Sumatra, Indonesia

Ceratocystis wilt disease has caused significant mortality in duku (Lansium domesticum) since 2014 and has now spread to all districts in South Sumatra, Indonesia. Recently, 16 isolates from duku representing populations from various districts in South Sumatra were isolated. Analysis for the morphological characteristic of the isolate showed that the population has a uniform morphology. Genetic analysis based on internal transcribed spacer (ITS) and β-tubulin sequences verified that the population has being dominated by the ITS5 haplotype of Ceratocystis fimbriata and a new ITS group, the ITS7b haplotype that was localized in Musi Banyuasin. Both haplotypes were highly pathogenic to duku. Inoculation tests on various forest and agroforestry plant hosts showed that both haplotypes were highly pathogenic to Acacia mangium, moderately pathogenic to Acacia carsicarpa, Eucalyptus urophylla, and Melaleuca cajuputi, but weakly pathogenic to Dyera costulata, Hevea brasiliensis, and Alstonia scholaris. Therefore, this pathogen becomes a serious threat to Indonesia's biodiversity due to its ability to infect forest and agroforestry plants, especially the indigenous ones.

Etiology of Botryosphaeria Panicle and Shoot Blight of Pistachio (Pistacia vera) Caused by Botryosphaeriaceae in Italy

Pistachio (Pistacia vera) is an important crop in Italy, traditionally cultivated in Sicily (southern Italy) for several decades now. In recent years, new orchards have been planted in new areas of the island. Field surveys conducted in 2019 revealed the presence of symptomatic trees showing shoot dieback, cankers, fruit spots, and leaf lesions. Isolations from symptomatic samples consistently yielded fungal species in the Botryosphaeriaceae family. Identification of collected isolates was conducted using morphological and molecular analyses. Morphological characterization was based on conidia measurements of representative isolates and also effects of temperatures on mycelial growth was evaluated. DNA data derived from sequencing the ITS, tef1-α, and tub2 gene regions were analyzed via phylogenetic analyses (maximum parsimony and maximum likelihood). Results of the analyses confirmed the identity of Botryosphaeria dothidea, Neofusicoccum hellenicum, and N. mediterraneum. Pathogenicity tests were conducted on detached twigs and in the fields both on shoots as well as on fruit clusters using the mycelial plug technique. The inoculation experiments revealed that among the Botryosphaeriaceae species identified in this study N. hellenicum (occasionally detected) and N. mediterraneum were the most aggressive based on lesion length on shoots and fruits. N. mediterraneum was the most widespread among the orchards while B. dothidea can be considered a minor pathogen involved in this complex disease of pistachio. Moreover, to our knowledge, this is the first report of N. hellenicum in Italy.

A New Disease for Europe of Ficus microcarpa Caused by Botryosphaeriaceae Species

The Indian laurel-leaf fig (Ficus microcarpa) is an important ornamental tree widely distributed in the urban areas of Italy. Surveys conducted in 2019 and 2020 on several tree-lined streets, squares, and public parks in Catania and Siracusa provinces (Sicily, southern Italy) revealed the presence of a new disease on mature trees. About 9% of approximately 450 mature plants showed extensive branch cankers and dieback. Isolations from woody tissues obtained from ten symptomatic plants consistently yielded species belonging to the Botryosphaeriaceae family. The identification of the recovered fungal isolates was based on a multi-loci phylogenetic (maximum parsimony and maximum likelihood) approach of the ITS, tef1-α, and tub2 gene regions. The results of the analyses confirmed the presence of three species: Botryosphaeria dothidea, Neofusicoccum mediterraneum, and N. parvum. Pathogenicity tests were conducted on potted, healthy, 4-year-old trees using the mycelial plug technique. The inoculation experiments revealed that all the Botryosphaeriaceae species identified in this study were pathogenic to this host. Previous studies conducted in California showed similar disease caused by Botryosphaeriaceae spp., and the pathogenic role of these fungi was demonstrated. To our knowledge, this is the first report of Botryosphaeriaceae affecting Ficus microcarpa in Europe.

Highly Efficient Generation of Canker-Resistant Sweet Orange Enabled by an Improved CRISPR/Cas9 System

Sweet orange (Citrus sinensis) is the most economically important species for the citrus industry. However, it is susceptible to many diseases including citrus bacterial canker caused by Xanthomonas citri subsp. citri (Xcc) that triggers devastating effects on citrus production. Conventional breeding has not met the challenge to improve disease resistance of sweet orange due to the long juvenility and other limitations. CRISPR-mediated genome editing has shown promising potentials for genetic improvements of plants. Generation of biallelic/homozygous mutants remains difficult for sweet orange due to low transformation rate, existence of heterozygous alleles for target genes, and low biallelic editing efficacy using the CRISPR technology. Here, we report improvements in the CRISPR/Cas9 system for citrus gene editing. Based on the improvements we made previously [dicot codon optimized Cas9, tRNA for multiplexing, a modified sgRNA scaffold with high efficiency, citrus U6 (CsU6) to drive sgRNA expression], we further improved our CRISPR/Cas9 system by choosing superior promoters [Cestrum yellow leaf curling virus (CmYLCV) or Citrus sinensis ubiquitin (CsUbi) promoter] to drive Cas9 and optimizing culture temperature. This system was able to generate a biallelic mutation rate of up to 89% for Carrizo citrange and 79% for Hamlin sweet orange. Consequently, this system was used to generate canker-resistant Hamlin sweet orange by mutating the effector binding element (EBE) of canker susceptibility gene CsLOB1, which is required for causing canker symptoms by Xcc. Six biallelic Hamlin sweet orange mutant lines in the EBE were generated. The biallelic mutants are resistant to Xcc. Biallelic mutation of the EBE region abolishes the induction of CsLOB1 by Xcc. This study represents a significant improvement in sweet orange gene editing efficacy and generating disease-resistant varieties via CRISPR-mediated genome editing. This improvement in citrus genome editing makes genetic studies and manipulations of sweet orange more feasible.

Neofusicoccum mediterraneum Is Involved in a Twig and Branch Dieback of Olive Trees Observed in Salento (Apulia, Italy)

Olive trees are infected and damaged by Botryosphaeriaceae fungi in various countries. The botryosphaeriaceous fungus Neofusicoccum mediterraneum is highly aggressive and is a major concern for olive groves in Spain and California (USA), where it causes 'branch and twig dieback' characterized by wood discoloration, bark canker, and canopy blight. During surveys of olive groves in Apulia (southern Italy), we noticed that-in some areas-trees were heavily affected by severe branch and twig dieback. In addition, chlorosis and the appearance of red-bronze patches on the leaf preceded the wilting of the foliage, with necrotic leaves persisting on the twigs. Given the severity of the manifestation in zones also subject to olive quick decline syndrome (OQDS) caused by Xylella fastidiosa subsp. pauca, we investigated the etiology and provide indications for differentiating the symptoms from OQDS. Isolation from diseased wood samples revealed a mycete, which was morphologically and molecularly identified as N. mediterraneum. The pathogenicity tests clearly showed that this fungus is able to cause the natural symptoms. Therefore, also considering the low number of tested samples, N. mediterraneum is a potential causal agent of the observed disease. Specifically, inoculation of the twigs caused complete wilting in two to three weeks, while inoculation at the base of the stem caused severe girdling wedge-shaped cankers. The growth rate of the fungus in in vitro tests was progressively higher from 10 to 30 °C, failing to grow at higher temperatures, but keeping its viability even after prolonged exposure at 50 °C. The capacity of the isolate to produce catenulate chlamydospores, which is novel for the species, highlights the possibility of a new morphological strain within N. mediterraneum. Further investigations are ongoing to verify whether additional fungal species are involved in this symptomatology.

Biological and molecular characterization of linalool-mediated field resistance against Xanthomonas citri subsp. citri in citrus trees

The biological and molecular traits of the Ponkan mandarin (Citrus reticulata Blanco) were characterized in an investigation of the mechanisms of field resistance against citrus canker disease caused by the bacterial pathogen, Xanthomonas citri subsp. citri (Xcc). Various conventional citrus varieties that show diverse responses to Xcc were investigated, and the temporal changes in Xcc titer in response to linalool concentrations among the varieties revealed differences in Xcc proliferation trends in the inoculated leaves of the immune, field-resistant and susceptible varieties. In addition, increased linalool accumulation was inversely related to Xcc titers in the field-resistant varieties, which is likely caused by host--pathogen interactions. Quantitative trait locus (QTL) analysis using the F1 population of the resistant Ponkan mandarin and susceptible 'Harehime' ('E-647' × 'Miyagawa-wase') cultivar revealed that linalool accumulation and Xcc susceptibility QTLs overlapped. These results provide novel insights into the molecular mechanisms of linalool-mediated field resistance to Xcc, and suggest that high linalool concentrations in leaves has an antibacterial effect and becomes a candidate-biomarker target for citrus breeding to produce seedlings with linalool-mediated field resistance against Xcc.

Limited Evidence for Accumulation of Latent Infections of Canker-Causing Pathogens in Shoots of Stone Fruit and Nut Crops in California

Prevalence of latent infections of the canker-causing fungi Botryosphaeria dothidea and species of Cytospora, Diplodia, Lasiodiplodia, Neofusicoccum, and Phomopsis in young shoots of almond, prune, and walnut trees in California was studied to test the hypotheses that latent infections accumulate from current-season shoots to 1-year-old shoots in the orchard and there are distinct associations among pathogen taxa present as latent infections in the same shoot. Samples of newly emerged and 1-year-old shoots were periodically collected in each almond, prune, and walnut orchard for two growing seasons. A real-time quantitative PCR assay was used to quantify latent infection with three parameters: incidence, molecular severity, and latent infection index. Diplodia spp. were absent from most samples. For almond, Lasiodiplodia spp. and Cytospora spp. were detected with a maximum incidence >90%, while B. dothidea and Neofusicoccum spp. incidence was <20% in most cases. In prune orchards, the incidence levels of B. dothidea were >50% in most cases, while those of Cytospora spp. and Lasiodiplodia spp. were 30 to 60% and 30 to 100%, respectively. For walnut, many samplings showed higher incidence in 1-year-old (30 to 80%) than in newly emerged shoots (10 to 50%). Accumulation of latent infection between the two shoot age classes was detected in only a few cases. The percentages of samples showing coexistence of two, three, and four pathogen taxa in the same shoot were 20 to 25, <10, and <5%, respectively. Pairwise associations among pathogen taxa in the same shoot were significant in many cases.

Occurrence of Canker and Wood Rot Pathogens on Stone Fruit Propagation Material and Nursery Trees in the Western Cape of South Africa

Dieback and canker of young stone fruit trees can cause suboptimal growth and even death under severe conditions. One source of inoculum of canker pathogens could be through nursery trees harboring latent infections that would not be visible to inspections done according to the deciduous fruit scheme. The objectives of this study were to identify the canker and wood rot fungal pathogens present in nursery stone fruit trees as well as in propagation material and to evaluate their pathogenicity. Isolations were made from scion and rootstock propagation material and from certified nursery stone fruit trees. The plant material sampled did not have any external symptoms. The certified nursery trees when cross-sectioned displayed brown discoloration from the pruning wound, the bud union, and often the crown. Fungal species isolated were identified by sequencing of the relevant barcoding genes and phylogenetic analyses thereof. Canker- and wood rot-associated fungi were identified. Buds used for budding had low levels of infection, with 1.2% of dormant buds infected and 0.4% of green buds infected. The dormant rootstock shoots had a canker pathogen incidence of 6.2% before they were planted in the nursery fields and increased inasmuch as the ungrafted, rooted rootstock plants had 11.1% infection with canker and wood rot pathogens. Out of 1,080 nursery trees, the canker- and wood rot-associated fungi infected 21.8% of trees. The canker-causing pathogens that were isolated the most were Cadophora luteo-olivacea and Diplodia seriata. A low incidence of wood rot fungi was found, with only 1.5% of nursery trees infected. In total, 26 new reports of fungal species on stone fruit in South Africa were made. Of these, 22 have not been found on stone fruit worldwide. The pathogenicity trials' results confirmed the pathogenic status of these newly reported species. All of the isolates tested formed lesions significantly longer than the control, 4 months after wound inoculation of 2-year-old shoots of two plum orchards. Lasiodiplodia theobromae was the most virulent species on both plum cultivars. The results of this research showed that nursery stone fruit trees and propagation material can harbor latent infections. Different management practices need to be evaluated to prevent these infections to ensure healthier stone fruit nursery trees.

Comparative genome analyses suggest a hemibiotrophic lifestyle and virulence differences for the beech bark disease fungal pathogens Neonectria faginata and Neonectria coccinea

Neonectria faginata and Neonectria coccinea are the causal agents of the insect-fungus disease complex known as beech bark disease (BBD), known to cause mortality in beech forest stands in North America and Europe. These fungal species have been the focus of extensive ecological and disease management studies, yet less progress has been made toward generating genomic resources for both micro- and macro-evolutionary studies. Here, we report a 42.1 and 42.7 mb highly contiguous genome assemblies of N. faginata and N. coccinea, respectively, obtained using Illumina technology. These species share similar gene number counts (12,941 and 12,991) and percentages of predicted genes with assigned functional categories (64 and 65%). Approximately 32% of the predicted proteomes of both species are homologous to proteins involved in pathogenicity, yet N. coccinea shows a higher number of predicted mitogen-activated protein kinase genes, virulence determinants possibly contributing to differences in disease severity between N. faginata and N. coccinea. A wide range of genes encoding for carbohydrate-active enzymes capable of degradation of complex plant polysaccharides and a small number of predicted secretory effector proteins, secondary metabolite biosynthesis clusters and cytochrome oxidase P450 genes were also found. This arsenal of enzymes and effectors correlates with, and reflects, the hemibiotrophic lifestyle of these two fungal pathogens. Phylogenomic analysis and timetree estimations indicated that the N. faginata and N. coccinea species divergence may have occurred at ∼4.1 million years ago. Differences were also observed in the annotated mitochondrial genomes as they were found to be 81.7 kb (N. faginata) and 43.2 kb (N. coccinea) in size. The mitochondrial DNA expansion observed in N. faginata is attributed to the invasion of introns into diverse intra- and intergenic locations. These first draft genomes of N. faginata and N. coccinea serve as valuable tools to increase our understanding of basic genetics, evolutionary mechanisms and molecular physiology of these two nectriaceous plant pathogenic species.

Genetic Variation for Economically Important Traits in Cupressus lusitanica in New Zealand

Increasing productivity and tolerance against cypress canker disease is an important goal in the Mexican white cypress breeding program in New Zealand, and screening has been in place since 1983. Cypress canker disease is caused by Seiridium cardinale and Seiridium cupressi, the current study presents the results of two progeny trials within the breeding program in the North Island of New Zealand. The trials were established as open-pollinated progeny tested and were assessed for diameter at breast height, branch size, canker severity score, malformation score, and stem straightness score and acceptability score. Heritability estimates were moderate ranging from 0.21 to 0.41 for diameter at breast height and from 0.14 to 0.31 for canker severity score. Stem form attributes showed heritability from 0.08 (malformation) to 0.38 (straightness). No trait showed any significant G × E interaction between investigated sites. This was supported by the very strong genetic correlations estimated between the traits recorded in Welcome Bay and Matata trials. Unfavourable genetic correlations ranging from 0.25 to 0.46 were found between diameter at breast height and canker severity score, indicating that the continued selection for genotypes with improved diameter at breast height would also increase susceptibility to cypress canker. Additionally, unfavourable genetic correlations ranging from 0.52 to 0.73 were found between branch size and diameter at breast height and should be considered in selection programs. The moderate heritability estimated for canker severity score indicates that breeding values for this trait could be predicted with acceptable accuracy and included in the breeding program for Cupressus lusitanica, enabling the identification of genotypes with tolerance to canker severity to be deployed to locations where cypress canker is present in New Zealand.

First report of Eutypa lata causing cankers and dieback in sweet cherry in Chile

Sweet cherry (Prunus avium) is one the most important fruit crops in Chile. Its production has significantly grown in recent years, reaching 228,448 tons exported in 2019/2020, to 47 countries. One of the main threats for this expanding crop are fungal pathogens, especially those that cause wood diseases. Cherry orchards (n=35) located in the central area of Chile, from Curicó (34°58'58''S 71°14.366'W) to Angol (37°47'42.7''S 72°42.982'W), were surveyed during 2020. Wood samples were collected (n= 72) from living branches and trunks showing dieback, cankers and dark necrosis, mostly wedge shaped. Small wood sections (0.5-cm) were cut off from the margin of the necrosis and surface disinfected using 0.5% v/v sodium hypochlorite. Sections were plated on a quarter-strength potato dextrose agar amended with 1mg/L tetracycline (PDA-tet). Plates were incubated at 25°C until mycelial development and subsequently the isolates were purified transferring excised fungal tips to PDA. Colonies (n=21) developed white cottony mycelia, which turned slightly greyish and flatter after 10-days at 25°C. Isolates developed black pycnidia which released beige conidial matrixes after subsequent 15-days at 25 +/-2°C and 12-h photoperiod. Conidia were hyaline, curved and filiform, measuring 19.8-(27.9)-36.7 μm length (lineal) x 1.2-(1.7)-1.9 μm width (n=70), according to Eutypa lata (Rappaz, 1984). DNA was extracted from mycelia of the representative isolates HMCe30a, HMCe41a, HMCe109c and HMCe110a. The partial β-tubulin gene was amplified using bt2A/bt2B primers (Glass & Donaldson 1995) and the internal transcribed spacer region was amplified using ITS1/ITS4 primers (White et al. 1990). Sequences were BLAST analyzed, finding that ITS shared 99% and βTUB 100% identity with E. lata strain CBS 208.87 (Rolshausen et al. 2006). Sequences were accessioned to GenBank (MW363035, MW363034, MW363033 and MW363032 [ITS], and MW366820, MW366819, MW366818and MW366817 [βTUB]). The isolates were inoculated on sweet cherry healthy plants cv. Kordia, produced by rooting scions in tap water amended with 500 ppm of indole-butyric acid, for 30 days. An injury was made in the upper third of the shoot using a sterile 0.5-cm diameter corkborer. Mycelial plugs were placed on the injuries and covered with plastic film, using sterile agar for controls (n=25). Plants were incubated in aerated tap water for 60 days at 23 +/-3 °C. After incubation, plants were cut exposing dark-brown necrotic lesions, while control plants remained asymptomatic. Moreover, 2-year old potted plants cv. Lapins were inoculated (n=3 per isolate) with mycelial plugs, on fresh cuts of their main lateral branches, in January 20th, and remained under partial shade for 72-days. After incubation, bark was removed from inoculated branches and the necrotic lesions length was measured. HMCe109c was the most virulent isolate (3.6 cm), followed by HMCe30a (2.1 cm), HMCe41a (1.9 cm) and HMCe110a (1.1 cm), while symptoms were not reproduced in controls. Fulfilling Koch's postulates, fungi were reisolated from all inoculated plants in both pathogenicity tests and no fungus was recovered from controls. To our knowledge this is the first report of Eutypa lata causing wood decay in sweet cherry in Chile. The pathogen was recently reported causing dieback of grapevines in Chile (Lolas et al. 2020). These are significant findings due to the frequent proximity of sweet cherry orchards and vineyards, which facilitates cross infections.

Evaluation of an Alternative Small Stem Assay for Blight Resistance in American, Chinese, and Hybrid Chestnuts (Castanea spp.)

We tested an alternative small stem assay (SSA) for blight resistance in chestnuts (Castanea spp.). Whereas standard SSAs are done by inoculating small incisions in stems, we cut off stems (4 to 5 mm diameter), inoculated the cut ends with discs of Cryphonectria parasitica inoculum, and covered them with plastic sleeves. This method was designed to be simple to implement, to consistently induce cankering, and to better enable seedlings to recover by developing shoots from the lower stem (standard SSAs delay removal of blighted stems until late in the growing season, if at all). We conducted six experiments with seedlings and orchard trees of Castanea dentata (susceptible), Castanea mollissima (resistant), and hybrids expected to vary in resistance. Experiments with seedlings and two of the three orchard experiments showed clear differentiation between susceptible and resistant types, especially >90 days postinoculation and when the orange-colored zone of the canker was measured. One orchard experiment failed to give clear results but was ended earlier (60 days) than the other experiments. We observed only two failed inoculations out of >200 performed. Comparisons with other studies suggest that this SSA method performs at least as well as the standard SSA method in distinguishing resistant and susceptible types, at least in seedlings. Survivorship after 1 year for seedlings inoculated in 2018 ranged from 70% for C. dentata to 100% for C. mollissima, and in 2019 they ranged from 40% in hybrids to 100% for C. mollissima. Deaths of seedlings after SSAs were mostly unrelated to the inoculations (e.g., root rot).

Fungal Pathogens Associated With Canker Diseases of Almond in California

Almond canker diseases are destructive and can reduce the yield as well as the lifespan of almond orchards. These diseases may affect the trunk and branches of both young and mature trees and can result in tree death soon after orchard establishment in severe cases. Between 2015 and 2018, 70 almond orchards were visited throughout the Central Valley of California upon requests from farm advisors for canker disease diagnosis. Two major canker diseases were identified, including Botryosphaeriaceae cankers and Ceratocystis canker. In addition, five less prevalent canker diseases were identified, including Cytospora, Eutypa, Diaporthe, Collophorina, and Pallidophorina canker. Seventy-four fungal isolates were selected for multilocus phylogenetic analyses of internal transcribed spacer region ITS1-5.8S-ITS2 and part of the translation elongation factor 1-α, β-tubulin, and glyceraldehyde 3-phosphate dehydrogenase gene sequences; 27 species were identified, including 12 Botryosphaeriaceae species, Ceratocystis destructans, five Cytospora species, Collophorina hispanica, four Diaporthe species, two Diatrype species, Eutypa lata, and Pallidophorina paarla. The most frequently isolated species were Ceratocystis destructans, Neoscytalidium dimidiatum, and Cytospora californica. Pathogenicity experiments on almond cultivar Nonpareil revealed that Neofusicoccum parvum, Neofusicoccum arbuti, and Neofusicoccum mediterraneum were the most virulent. Botryosphaeriaceae cankers were predominantly found in young orchards and symptoms were most prevalent on the trunks of trees. Ceratocystis canker was most commonly found in mature orchards and associated with symptoms found on trunks or large scaffold branches. This study provides a thorough examination of the diversity and pathogenicity of fungal pathogens associated with branch and trunk cankers of almond in California.

New records of Celoporthe guangdongensis and Cytospora rhizophorae on mangrove apple in China

BACKGROUND

Sonneratia apetala Francis Buchanan-Hamilton (Sonneratiaceae, Myrtales), is a woody species with high adaptability and seed production capacity. S. apetala is widely cultivated worldwide as the main species for mangrove construction. However, the study of diseases affecting S. apetala is limitted, with only a few fungal pathogens being recorded. Cryphonectriaceae (Diaporthales) species are the main pathogens of plants. They can cause canker diseases to several trees and thereby seriously threaten the health of the hosts. These pathogens include Cryphonectria parasitica (Cryphonectriaceae) causing chestnut blight on Castanea (Rigling and Prospero 2017) and Cytospora chrysosperma (Cytosporaceae) causing polar and willow canker to Populus and Salix (Wang et al. 2015) . Therefore, the timely detection of of Cryphonectriaceae canker pathogens on S. apetala is extremely important for protecting the mangrove forests.

NEW INFORMATION

Two diaporthalean fungi, Celoporthe guangdongensis and Cytospora rhizophorae have been reported for the first time to cause canker on the branches of S. apetala. C. guangdongensis is significantly pathogenic and C. rhizophorae is saprophytic on S. apetala.

Equine Hoof Canker: Bovine Papillomavirus Infection Is Not Associated With Impaired Keratinocyte Differentiation

Impaired keratinocyte differentiation has recently been suggested as a key event in equine hoof canker development. Koilocytotic appearance of keratinocytes, one of the most characteristic morphological alterations in hoof canker tissue, is also a common marker for papillomavirus (PV) infection, and bovine PV-1 and/or -2 (BPV-1/2) has previously been detected in equine canker patients. Therefore, the present study aimed to correlate the frequency and severity of koilocytotic keratinocytes with BPV detection in hoof canker samples. Hoof tissue of 5/18 canker-affected horses and 2/6 control horses tested positive for BPV-1/2 DNA using polymerase chain reaction. Thus, no association between the presence of BPV-1/2 papillomaviral DNA and koilocytotic appearance was found. Proteins associated with but not specific for PV infection were also investigated. Using immunohistochemistry, specific adhesion molecules (E-cadherin and β-catenin) and intermediate filaments (keratins 6 and 14) important for intact epidermal barrier function and keratinocyte differentiation were documented in control samples (n = 6) and in hoof canker tissue samples (n = 19). Altered expression patterns of intermediate filaments and adhesion molecules were demonstrated in canker tissue, confirming the importance of incomplete keratinocyte differentiation, as well as the crucial role of keratinocyte differentiation in hoof canker.

Reevaluating Cryphonectriaceae and allied families in Diaporthales

The Diaporthales (Sordariomycetes) includes many important families of plant pathogenic fungi, such as the notorious Cryphonectriaceae. The aim of the present study was to reevaluate this family, along with other families in Diaporthales. Based on phylogenetic analyses using combined sequence data of the internal transcribed spacer (ITS) region, large subunit of the nrDNA (28S), and the translation elongation factor 1-alpha (tef1-α) and DNA-directed RNA polymerase II second largest subunit (rpb2) genes, Cryphonectriaceae is separated into two subclades, comprising 21 genera and 55 species. Foliocryphiaceae, fam. nov., is morphologically and phylogenetically its closest relative but is distinct due to its phylogeny and dimorphic conidia. Mastigosporellaceae, fam. nov., is distinguished from other families in Diaporthales by owning apical conidial appendages. Neocryphonectria, gen. nov., within the family Foliocryphiaceae, with two species associated with Carpinus canker in China, is characterized by fusoid, aseptate macroconidia. Additionally, two new combinations are proposed, namely, Cryphonectria citrine, based on Chromendothia citrine, and Cytospora viridistroma, based on Endothia viridistoma. Based on results obtained in this study, 31 families are accepted into Diaporthales.

Canker and Wood Rot Pathogens Present in Young Apple Trees and Propagation Material in the Western Cape of South Africa

Canker and wood rot pathogens cause dieback and, in severe cases, the death of young apple trees. Recently, a higher occurrence of cankers was observed on 1-year-old apple trees in the Western Cape Province of South Africa. This study aimed to assess the phytosanitary status of nursery trees and propagation material as possible inoculum sources for canker pathogens. Thirteen 1-year-old apple orchards showing canker or dieback symptoms were sampled. Certified nursery apple trees were collected from four nurseries as well as scion and rootstock mother plant material. Isolations were made from the discoloration observed in the vascular tissue of the plant parts and from asymptomatic material. Possible canker and wood rot species were identified with PCR and sequence comparisons of the relevant gene regions and phylogenetic analyses. Similar canker and wood rot species were isolated from 1-year-old diseased apple trees, nursery apple trees, and the propagation material. Forty-five fungal species associated with canker or wood rot symptoms were identified. The top five most abundant fungal species found causing disease on commercial 1-year-old trees were also found in high numbers causing latent infection in certified apple nursery trees. These species were Didymosphaeria rubi-ulmifolii sensu lato, Diplodia seriata, Schizophyllum commune, Didymella pomorum, and Coniochaeta fasciculata, with D. rubi-ulmifolii sensu lato being the dominant species in both sampling materials. In all, 65% of certified nursery apple trees, 5% of scion shoots used for budding, and 21% of rooted rootstock cuttings from layer blocks had latent infections of canker and wood rot pathogens. Pathogenicity trials were conducted with isolates of 39 species, inoculated onto 2-year-old branches of 14-year-old Golden Delicious trees. All species caused lesions that were significantly longer than the control. This study confirmed the presence of canker and wood rot pathogens in apple propagation material as well as certified nursery apple trees, which will aid the improvement of management practices in nurseries.

Ecology and Epidemiology of Diseases of Nut Crops and Olives Caused by Botryosphaeriaceae Fungi in California and Spain

In recent decades, the cultivated area and production of nuts and olives have increased, driven by an increasing consumer interest in healthier food. Diseases of almond, pistachio, olive, and walnut crops caused by species belonging to the Botryosphaeriaceae family have caused concern worldwide. Although considerable progress has been made in elucidating the etiology of these diseases, scientific knowledge of other aspects of these diseases is more limited. In this article, we present an overview of the most important diseases caused by Botryosphaeriaceae fungi affecting almond, pistachio, olive, and walnut crops by focusing on ecology and epidemiology, primarily in California and Spain.

Cryphalus eriobotryae sp. nov. (Coleoptera: Curculionidae: Scolytinae), a New Insect Pest of Loquat Eriobotrya japonica in China

A previously unknown bark beetle species, Cryphalus eriobotryae sp. nov. Johnson, 2019 has emerged as a lethal pest of loquat (Eriobotrya japonica) in China. The description of new species has been provided. The new species is distinguished from the other Cryphalus by the weakly aciculate frons, by the antennae, with unevenly spaced procurved sutures, by the short pronotal disc, with hair-like setae, and by the widely spaced mesocoxae. The survey of plantation records from around Suzhou suggests that this beetle was introduced from another area not long before 2017. In the surveyed loquat plantation in 2018, 20-90% of trees showed signs of infestation, and 5% were killed in 2018, resulting in the death of over 1000 trees. Outbreaks of the apparently loquat-specific Cryphalus eriobotryae can be diagnosed by hundreds of cankers on the trunk, and wilted foliage. This pest is of concern as a loquat plantation pest and as a pest of fruit production and ornamental trees within Suzhou, and globally.

Ancrocorticia populi gen. nov., sp. nov, isolated from the symptomatic bark of Populus × euramericana canker

A Gram-staining positive facultative anaerobic, non-motile strain, sk1b4^T , was isolated from canker of symptomatic bark tissue of a Populus × euramericana. 16S rRNA gene sequence analyses showed that strain sk1b4^T shared the highest similarity with Arcanobacterium phocisimile (94.1%). Within the phylogenetic tree, the novel isolate formed a distinct branch from Actinobaculum, Arcanobacterium, and Trueperella. The percentage of conserved proteins calculated from genomic sequence indicated a low level of relatedness between the novel strain and its phylogenetic neighbors. Growth of the novel strain occurred at temperatures between 10 and 41°C, and within a pH range of 6.0-9.0; optimal growth occurred at 30°C and at pH 6.0-9.0. Growth also occurred within a NaCl concentration of 1%-5% (w/v). The major fatty acids of the strain were C_14:0 , C_16:0 , and C_18:1 ω9c_, and major polar lipids were glycolipid, phosphatidylinositol mannoside, phospholipid, diphosphatidylglycerol, and phosphatidylglycerol. Respiratory quinone was absent. On the basis of phenotypic and genotypic characteristics, we propose that the novel isolate should be classified as a novel species in a new genus: Ancrocorticia populi gen. nov., sp. nov. The type strain is sk1b4^T (=CFCC 14564^T = KCTC 39919^T ).

Neocosmospora perseae sp. nov., causing trunk cankers on avocado in Italy

Trunk and branch cankers are among the most important diseases compromising avocado production worldwide. A novel species, Neocosmospora perseae sp. nov. is described isolated from trunk lesions on Persea americana in the main avocado producing area of Sicily, Italy. The new species is characterised using a polyphasic approach including morphological characters and a multilocus molecular phylogenetic analysis based on partial sequences of the translation elongation factor-1α, the internal transcribed spacer regions plus the large subunit of the rDNA cistron, and the RNA polymerase II second largest subunit. Pathogenicity tests and the fulfilment of Koch's postulates confirm N. perseae as a novel canker pathogen of Persea americana.

Diaporthe diversity and pathogenicity revealed from a broad survey of grapevine diseases in Europe

Species of Diaporthe are considered important plant pathogens, saprobes, and endophytes on a wide range of plant hosts. Several species are well-known on grapevines, either as agents of pre- or post-harvest infections, including Phomopsis cane and leaf spot, cane bleaching, swelling arm and trunk cankers. In this study we explore the occurrence, diversity and pathogenicity of Diaporthe spp. associated with Vitis vinifera in major grape production areas of Europe and Israel, focusing on nurseries and vineyards. Surveys were conducted in Croatia, Czech Republic, France, Hungary, Israel, Italy, Spain and the UK. A total of 175 Diaporthe strains were isolated from asymptomatic and symptomatic shoots, branches and trunks. A multi-locus phylogeny was established based on five genomic loci (ITS, tef1, cal, his3 and tub2), and the morphological characters of the isolates were determined. Preliminary pathogenicity tests were performed on green grapevine shoots with representative isolates. The most commonly isolated species were D. eres and D. ampelina. Four new Diaporthe species described here as D. bohemiae, D. celeris, D. hispaniae and D. hungariae were found associated with affected vines. Pathogenicity tests revealed D. baccae, D. celeris, D. hispaniae and D. hungariae as pathogens of grapevines. No symptoms were caused by D. bohemiae. This study represents the first report of D. ambigua and D. baccae on grapevines in Europe. The present study improves our understanding of the species associated with several disease symptoms on V. vinifera plants, and provides useful information for effective disease management.

Ectopic accumulation of linalool confers resistance to Xanthomonas citri subsp. citri in transgenic sweet orange plants

In order to clarify whether high linalool content in citrus leaves alone induces strong field resistance to citrus canker caused by Xanthomonas citri subsp. citri (Xcc), and to assess whether this trait can be transferred to a citrus type highly sensitive to the bacterium, transgenic 'Hamlin' sweet orange (Citrus sinensis L. Osbeck) plants over-expressing a linalool synthase gene (CuSTS3-1) were generated. Transgenic lines (LIL) with the highest linalool content showed strong resistance to citrus canker when spray inoculated with the bacterium. In LIL plants inoculated by wounding (multiple-needle inoculation), the linalool level was correlated with the repression of the bacterial titer and up-regulation of defense-related genes. The exogenous application of salicylic acid, methyl jasmonate or linalool triggered responses similar to those constitutively induced in LIL plants. The linalool content in Ponkan mandarin leaves was significantly higher than that of leaves from six other representative citrus genotypes with different susceptibilities to Xcc. We propose that linalool-mediated resistance might be unique to citrus tissues accumulating large amounts of volatile organic compounds in oil cells. Linalool might act not only as a direct antibacterial agent, but also as a signal molecule involved in triggering a non-host resistance response against Xcc.

A Proteomic Study of Clavibacter Michiganensis Subsp. Michiganensis Culture Supernatants

Clavibacter michiganensis, subsp. michiganensis is a Gram-positive plant pathogen infecting tomato (Solanum lycopersicum). Despite a considerable economic importance due to significant losses of infected plants and fruits, knowledge about virulence factors of C. michiganensis subsp. michiganensis and host-pathogen interactions on a molecular level are rather limited. In the study presented here, the proteome of culture supernatants from C. michiganensis subsp. michiganensis NCPPB382 was analyzed. In total, 1872 proteins were identified in M9 and 1766 proteins in xylem mimicking medium. Filtration of supernatants before protein precipitation reduced these to 1276 proteins in M9 and 976 proteins in the xylem mimicking medium culture filtrate. The results obtained indicate that C. michiganensis subsp. michiganensis reacts to a sucrose- and glucose-depleted medium similar to the xylem sap by utilizing amino acids and host cell polymers as well as their degradation products, mainly peptides, amino acids and various C5 and C6 sugars. Interestingly, the bacterium expresses the previously described virulence factors Pat-1 and CelA not exclusively after host cell contact in planta but already in M9 minimal and xylem mimicking medium.

Genome, Proteome and Structure of a T7-Like Bacteriophage of the Kiwifruit Canker Phytopathogen Pseudomonas syringae pv. actinidiae

Pseudomonas syringae pv. actinidiae is an economically significant pathogen responsible for severe bacterial canker of kiwifruit (Actinidia sp.). Bacteriophages infecting this phytopathogen have potential as biocontrol agents as part of an integrated approach to the management of bacterial canker, and for use as molecular tools to study this bacterium. A variety of bacteriophages were previously isolated that infect P. syringae pv. actinidiae, and their basic properties were characterized to provide a framework for formulation of these phages as biocontrol agents. Here, we have examined in more detail φPsa17, a phage with the capacity to infect a broad range of P. syringae pv. actinidiae strains and the only member of the Podoviridae in this collection. Particle morphology was visualized using cryo-electron microscopy, the genome was sequenced, and its structural proteins were analysed using shotgun proteomics. These studies demonstrated that φPsa17 has a 40,525 bp genome, is a member of the T7likevirus genus and is closely related to the pseudomonad phages φPSA2 and gh-1. Eleven structural proteins (one scaffolding) were detected by proteomics and φPsa17 has a capsid of approximately 60 nm in diameter. No genes indicative of a lysogenic lifecycle were identified, suggesting the phage is obligately lytic. These features indicate that φPsa17 may be suitable for formulation as a biocontrol agent of P. syringae pv. actinidiae.

Responsiveness of different citrus genotypes to the Xanthomonas citri ssp. citri-derived pathogen-associated molecular pattern (PAMP) flg22 correlates with resistance to citrus canker

The bacterial agent of citrus canker disease (Xanthomonas citri ssp. citri, Xcc) has caused tremendous economic losses to the citrus industry around the world. Pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) is important to plant immunity. In this study, we compared the defence responses of citrus canker-resistant and citrus canker-susceptible genotypes to the Xcc-derived PAMP flg22 (Xflg22) by analysing the expression of 20 citrus defence-associated genes. We showed that, in the most resistant genotype, 'Nagami' kumquat, there was significant induction of several defence genes (EDS1, NDR1, PBS1, RAR1, SGT1, PAL1, NPR2 and NPR3) as early as 6 h and up to 72 h after Xflg22 treatment. At the other end of the spectrum, highly susceptible 'Duncan' grapefruit showed no induction of the same defence genes, even 120 h after treatment. Citrus genotypes with partial levels of resistance showed intermediate levels of transcriptional reprogramming that correlated with their resistance level. Xflg22 also triggered a rapid oxidative burst in all genotypes which was higher and accompanied by the induction of PTI marker genes (WRKY22 and GST1) only in the more resistant genotypes. Pretreatment with Xflg22 prior to Xcc inoculation inhibited bacterial growth in kumquat, but not in grapefruit. A flagellin-deficient Xcc strain (XccΔfliC) showed greater growth increase relative to wild-type Xcc in kumquat than in grapefruit. Taken together, our results indicate that Xflg22 initiates strong PTI in canker-resistant genotypes, but not in susceptible ones, and that a robust induction of PTI is an important component of citrus resistance to canker.

Huntiella decorticans sp. nov. (Ceratocystidaceae) associated with dying Nothofagus in Patagonia

During a survey of ophiostomatoid fungi in native forests of southern Argentina, several isolates of Huntiella species were obtained from Nothofagus trees. Sequences of multiple gene regions were used to identify these fungi, and their pathogenicity was tested on N. pumilio and N. dombeyi. Phylogenetic analyses revealed a novel taxon described here as H. decorticans sp. nov. Inoculations on N. dombeyi and N. pumilio in the forest showed that H. decorticans is able to produce localized lesions on healthy Nothofagus trees.

Wombs, Worms and Wolves: Constructing Cancer in Early Modern England

This essay examines medical and popular attitudes to cancer in the early modern period, c.1580-1720. Cancer, it is argued, was understood as a cruel and usually incurable disease, diagnosable by a well-defined set of symptoms understood to correspond to its etymological root, karkinos (the crab). It was primarily understood as produced by an imbalance of the humours, with women being particularly vulnerable. However, such explanations proved inadequate to make sense of the condition's malignancy, and medical writers frequently constructed cancer as quasi-sentient, zoomorphising the disease as an eating worm or wolf. In turn, these constructions materially influenced medical practice, in which practitioners swung between anxiety over 'aggravating' the disease and an adversarial approach which fostered the use of radical and dangerous 'cures' including caustics and surgery.

Resolving the Diplodia complex on apple and other Rosaceae hosts

Diplodia species are known as pathogens on many woody hosts, including fruit trees, worldwide. In this study a collection of Diplodia isolates obtained mostly from apple and other Rosaceae hosts were identified based on morphological characters and DNA sequence data from ITS and EF1-α loci. The results show that the diversity of species associated with twig and branch cankers and fruit rot of apples is larger than previously recognised. Four species were identified, namely D. seriata and D. malorum (which is here reinstated for isolates with D. mutila-like conidia). Diplodia intermedia sp. nov. is closely related to D. seriata, and D. bulgarica sp. nov. is morphologically and phylogenetically distinct from all Diplodia species reported from apples.

Treponemes-infected canker in a Japanese racehorse: efficacy of maggot debridement therapy

A 3-year-old thoroughbred colt presented with canker on its left hind foot. Subsequent development of cottage cheese-like horns and dermatitis disturbed healing, despite the use of miscellaneous orthodox treatment approaches to the lesions. Histological examination revealed exudative and suppurative dermatitis, and proliferatively suppurative epidermitis infected with helically coiled treponemes. Total debridement under general anesthesia led to a temporary improvement, but the ground surface regenerated abnormal epidermis similar to that observed initially after surgery. Maggot debridement therapy (MDT) was attempted, which removed all the abnormal tissue. After MDT, general farriery trimming helped to correct the distorted ground surface, and the horse returned to constant training and eventually raced. This case shows that MDT was successfully used for treatment of an intractable and treponemes-infected canker.

Dolabra nepheliae on rambutan and lychee represents a novel lineage of phytopathogenic Eurotiomycetes

Rambutan (Nephelium lappaceum) and lychee (Litchi chinensis) are tropical trees in the Sapindaceae that produce delicious edible fruits and are increasingly cultivated in tropical regions. These trees are afflicted with a stem canker disease associated with the ascomycete Dolabra nepheliae. Previously known from Asia and Australia, this fungus was recently reported from Hawaii and Puerto Rico. The sexual and asexual states of Dolabra nepheliae are redescribed and illustrated. In addition, the ITS and large subunit of the nuclear ribosomal DNA plus fragments from the genes RPB2, TEF1, and the mitochondrial small ribosomal subunit were sequenced for three isolates of D. nepheliae and compared with other sequences of ascomycetes. It was determined that D. nepheliae represents a new lineage within the Eurotiomycetes allied with Phaeomoniella chlamydospora, the causal agent of Petri grapevine decline.

Water stress and Sphaeropsissapinea as a latent pathogen of red pine seedlings

•  The role of water stress in the initiation of collar rot by Sphaeropsis sapinea in asymptomatically colonized Pinus resinosa seedlings is reported. • Mortality and frequency of identification of the pathogen was quantified for seedlings subjected to different water regimes or watering regime-fungicide (benomyl) combinations in glasshouse experiments. •  In experiment 1, seedling mortality ranged from 8% of repeatedly watered seedlings to 50% of those in the driest regime; data analysis indicated a high probability that mortality was not independent of watering regime. Seedlings developed symptoms resembling those of Sphaeropsis collar rot, and S. sapinea was identified from living (42%) and dead (92%) seedlings. In experiment 2, mortality of repeatedly watered seedlings was low, irrespective of fungicide application. For nonwatered seedlings, however, mortality was greater among seedlings not treated with fungicide (61%) than among benomyl-treated seedlings (37%); data analysis indicated a high probability that mortality was not independent of fungicide treatment. • Sphaeropsis sapinea can act as a latent pathogen; physiological alteration, through water stress, can effect release from the quiescent condition to result in rapid disease development.

Seasonal Development of Phomopsis Shoot Blight of Peach and Effects of Selective Pruning and Shoot Debris Management on Disease Incidence

Seasonal development of shoot blight of peach caused by a Phomopsis sp. was evaluated in Oconee, Hall, and Peach counties in Georgia from April 1994 through May 1996. The frequency of infected buds in all three locations was highest during spring (mid-March to mid-May) and fall (early September to mid-October). The frequency of infected buds was highest in Hall County, which is the northernmost sampling location, followed by Oconee and Peach counties, which are located further south. During the same period of time, the effects of selective pruning and shoot debris management on disease incidence were evaluated in orchards in Oconee and Hall counties from May 1994 through May 1996. Selective pruning of infected shoots in May and October each year, following the major periods of infection, significantly reduced disease incidence during the following seasons in both locations. Disease incidence was similar regardless of whether shoot debris were left under the tree or removed from the orchard and destroyed. Our study indicates that major periods of infection of peach shoots by the Phomopsis sp. occur in the spring during the period of bud break, and in the fall when dormant buds and leaf scars are present. Additionally, our study indicates that reduction of inoculum by selectively removing infected shoots from the trees following the major periods of infection may significantly reduce disease incidence, although it may not eliminate the disease. Removal of infected shoot debris from the orchard does not appear to be necessary following pruning.