First Report of Calosphaeria pulchella causing Canker and Twig Dieback of Peach (Prunus persica) in California, U.S.A.

California leads the United States in peach (Prunus persica L.) production, with approximately 505,000 tons produced in 2021 and valued at $378.3 million (California Agriculture Statistics Review, 2021-2022). During the spring and summer of 2023, twig and branch dieback were observed in three peach orchards (cvs. Late Ross and Starn) in San Joaquin County, California. Wood cankers and discoloration also occurred in branches, generally initiating at pruning wounds. Approximately 8 symptomatic twigs or branches per orchard were collected to proceed with the isolation of necrotic tissues on acidified potato dextrose agar (APDA). Isolations consistently yielded colonies of the fungal pathogen Calosphaeria pulchella (Pers. : Fr.) J. Schröt. (Réblová et al. 2004; Trouillas et al. 2012). Pure cultures were obtained by transferring single hyphal tips onto new APDA Petri plates. Colonies on APDA grew dark pink to red or purple in their center, with a white margin. Conidiogenesis was phialidic, producing round conidial masses at the tip of phialides. Conidia were produced abundantly on APDA, and were hyaline, allantoid to oblong-ellipsoidal, 4 to 5.5 (7) × 1.2 to 2.3 µm (n = 60). Two representative isolates (SJC-62 and SJC-64) were selected for genomic DNA extraction and sequencing of the internal transcribed spacer region (ITS) using ITS5/ITS4 universal primers and the beta-tubulin (TUB2) gene region using primers Bt2a and Bt2b. Consensus sequences of the two genes for the two isolates (ITS: PP063990, PP063991; TUB2: PP068303, PP068304) were compared to reference sequences (Réblová et al. 2015; Trouillas et al. 2012) using BLAST analysis. The ITS sequences of SJC-62 and SJC-64 were 99.8 and 99.5% identical to that of C. pulchella ex-type strain CBS 115999 (NR145357) and reference strain SS07 (HM237297); the TUB2 sequences were at least 98.5% identical to that of C. pulchella CBS 115999 (KT716476). Pathogenicity tests were conducted in 2- to 3-year-old healthy branches on 7-year-old peach trees, cvs. Loadel, Late Ross and Starn using the two fungal isolates and a control treatment (1 branch per treatment and 3 branches per tree) on each of 8-tree replicates. Branches were inoculated in June 2023 following wounding with a 5 mm cork borer to remove the bark and placing an agar plug from the margin of 10-day-old colonies on APDA directly into the fresh wound. Sterile agar plugs were used as controls. Inoculation sites were covered with petroleum jelly and wrapped with Parafilm to retain moisture. The experiment was completed twice. After four months, cankers and vascular discolorations developed around the inoculation sites. Length of vascular discoloration in inoculated branches averaged 72, 75, and 79 mm, for the Loadel, Starn, and Late Ross cvs., respectively. Calosphaeria pulchella was re-isolated from inoculated branches at 80 to 100% recovery rate, thus fulfilling Koch's postulates. The average length of vascular discoloration in the control was 13.5 mm and no fungi were recovered from control branches. Calosphaeria canker caused by C. pulchella is a global disease of sweet cherry. Recently, it was reported to cause cankers in peach trees in Chile (Grinbergs et al. 2023). To our knowledge, this is the first report of C. pulchella causing cankers and twig dieback of peach trees in the United States. These findings improve our knowledge of the etiology of canker diseases affecting peach trees and is critical for the development of effective disease management strategies.

Identification of fungal species associated with gall oak (Quercus infectoria Oliv.) decline in Iran.

The gall oak (Quercus infectoria Oliv.) tree is one of the most important and valuable forestry species in the Northern Zagros forests in the west of Iran. Gall oak decline is considered to be one of the most important diseases currently affecting the oak Zagros forests in Iran. The main objective of the present study, conducted in the years 2021-2023, was to investigate the possible role of fungi as causative agents of gall oak dieback in the Zagros forests of Iran. Wood samples were taken from gall oak trees showing canker, dieback, and internal wood discoloration symptoms. Fungal isolates recovered from gall oak trees were identified based on cultural and morphological characteristics, as well as phylogenetic analyses using DNA sequencing of the internal transcribed spacer region of rDNA (ITS) and partial beta-tubulin (tub2). Achaetomium aegilopis, Alternaria tenuissima, Apiospora intestine, Botrytis cinerea, Coniochaeta sp., Coniothyrium palmarum, Coniothyrium sp., Cytospora rhodophila, Dialonectria episphaeria, Diatrype sp., Diatrypella macrospora, Endoconidioma populi, Fonsecazyma sp., Fusarium ipomoeae, Jattaea discrete, Kalmusia variispora, Microsphaeropsis olivacea, Neoscytalidium dimidiatum, Paecilomyces lecytidis, Paramicrosphaeropsis eriobotryae, Paramicrosphaeropsis ellipsoidea, and Seimatosporium pezizoides were identified from diseased trees. Pathogenicity tests were performed by artificial inoculation of excised branches of healthy gall oak trees under controlled conditions and evaluated after 35 days by measuring the discolored lesion length at the inoculation site. N. dimidiatum was the most virulent species and caused the longest wood necrosis within 35 days of inoculation. In the greenhouse test, only some species induced typical symptoms of canker. All isolated fungi are reported for the first time on gall oak trees in the world.

First report of Rhizoctonia solani AG-2-2 IIIB causing Rice sheath blight in China.

Rice (Oryza sativa) is an important crop worldwide, rice is susceptible to many pathogens, one of the most significant being Rice Sheath Blight, caused by Rhizoctonia solani. This disease initially produces cloudy spots on the leaf sheaths and later affects grain filling, resulting in yield losses of over 45%（Chen et al. 2013） when severe. In many southern rice-growing areas of China, the impact of this disease has risen to become the most damaging of the three major rice diseases (Margani et al. 2018). In July 2023, In Yongfu County, Guangxi (110.022°E, 25.010°N), symptoms of rice sheath blight were observed. The leaf sheaths were affected, with small, water-soaked, dark green spots with indistinct edges appearing near the water surface. These spots gradually expanded into elliptical or cloud-like lesions. Eventually, the center of the lesions turned straw-yellow to grayish-white, while the edges turned brown to dark brown. Often, several lesions merged into large cloud-like patches. Fifteen symptomatic sheaths were collected disinfecting pieces of necrotic tissue with 3% NaClO for 1.5 minutes, followed by 75% alcohol for 1 minute. The pieces were then rinsed with sterile distilled water, subsequently plated on Potato Dextrose Agar in Petri dishes, and incubated at 28°C in the dark. One isolate was obtained from each diseased plant using the hyphal tip method. (Feng et al. 2008). Isolates were obtained and displayed initially white mycelium and gradually turned brown after three to four days. Septate hyphae were 4.27 to 10.73 µ m (average 6.41 µ m) in diameter and branched at Right angle or acute angle with a constriction at the origin of the branch point. Staining with 1% safranin O and 3% KOH solution (Bandoni 1979) revealed multinucleated cells (three to nine nuclei per cell, n = 144). In summary, these characteristics were consistent with the description of Rhizoctonia solani Kühn (Meyer et al. 1990). The anastomosis group (AG) was confirmed by selecting three representative isolates (GL-Q-10, GL-Q-13, GL-Q-15) for molecular identification. The target DNA was extracted using Chelex-100. The internal transcribed spacer (ITS) region was amplified and sequenced with primers ITS1 and ITS4. The sequences were deposited in GenBank (ITS, PQ047154, PQ047150, and PQ047151 The base pairs are respectively 713bp, 715bp and 776bp, respectively). Upon searching GenBank, accession number MT385836 was found (Zhou et al. 2021), which has a similarity of 99.15% with PQ047154, 98.87% with PQ047150, and 99.30% with PQ047151. Phylogenetic tree analysis based on ITS sequences showed that the isolates clustered monophyletically with strains of R. solani AG-2-2 IIIB. The fusion group of the strain is verified by the shape and color of its mycelial growth on PDA at 35°C, enabling the distinct differentiation of AG-2-2 IIIB from AG-2-2 IV in terms of both morphology and coloration.（Aktaruzzaman et al. 2019） Pathogenicity tests involved culturing the pathogenic bacteria on PDA for 7-10 days, Then, 10 healthy rice plants (greenhouse potted rice variety Dian Heyou 615) were selected at the heading stage, and 5 plants were inoculated on the leaf sheaths with 5 strains of 5 mm fungus cake with pathogenic bacteria and 5 plants without pathogenic bacteria (The rice soil was disinfected), wrapped in cotton for moisture retention. All plants were sealed in transparent plastic bags and incubated in a greenhouse at 30 °C for 7-15 days, with daily moisturizing using sterile distilled water (Humidity control at 70%). Seven days postinoculation, Those containing pathogenic bacteria have symptoms of rice sheath blight, No symptoms were detected on control plants. Rhizoctonia solani AG-2-2 IIIB was re-isolated from the inoculated plants as previously described, thus fulfilling Koch's postulates. The pathogenicity tests were repeated three times. At present, Rhizoctonia solani AG-2-2 IIIB is primarily pathogenic in plants such as sugar beet and beans. It has only been reported in Japan and other countries to cause rice disease (Engelkes et al. 1996; Kenji Inagaki et al. 2004), and Rhizoctonia solani AG-2-2 IIIB has never been reported in China to cause disease in rice. To our knowledge, this study is the first to identify Rhizoctonia solani AG-2-2 IIIB causing rice sheath blight in China. This finding will aid further research on rice sheath blight defense strategies and contribute to the development of better management practices for this disease.

First Report of Fire Blight Caused by Erwinia amylovora on Pear in Saudi Arabia.

In the spring of 2020 and 2021, pear trees (Pyrus communis cv. Williams) in orchards (27°46'36.0"N 42°29'44.7"E, 30°00'00.2"N 40°15'11.8"E, and 28°44'52.9"N 36°18'47.8" E) in Hail, Al Jouf, and Tabuk regions exhibited fire blight symptoms. After removing bark, the affected trees showed shoot blight, brown-blighted shoot tips and blossom blight, dead flowers on the stems, and reddish-colored cankers. The disease incidence varied from 10% to 25%. Pathogen was isolated from 21 symptomatic samples including fruits, flowers, and shoots. Bacteria were isolated from washed tissues on King's B (KB) and semi-selective CCT media (Ishimaru and Klos, 1984). After 48 hours, colonies resembling Erwinia amylovora on KB media were 1.5-2 mm in diameter, white, circular, slightly convex, with a smooth surface, and exhibited no fluorescence under ultraviolet light. Colonies on CCT after 72 h were 3-4 mm in diameter, mucoid with shiny surfaces, semitransparent, speckled with craters, and slightly violet. All isolates were purified by subculturing on KB. All isolates were Gram-negative and rod-shaped, fermentative of glucose, positive for catalase and negative for oxidase, and potato rot. They induced a hypersensitive reaction when infiltrated in tobacco leaves (cv. Xanthi). Based on morphology and biochemical tests (EPPO, 2004), the strains were identified as Erwinia sp. Twenty-six strains from Saudi Arabia (SA) and the reference strain (NCPPB 683T) hydrolyzed gelatin and formed white, highly mucous colonies on the levan medium. These strains could not reduce nitrate to nitrite and tested negative for urease and indole production. All the isolates and the reference strain were confirmed to be E. amylovora based on a PCR 0.9-kb DNA fragment amplification with a species-specific primer set, A/B targets pEA29 (Bereswill et al. 1992). 16S-rDNA fragments from Saudi isolates were amplified with 27F and 1492R primers (Lane, 1991). Purified amplicons from PCR were sequenced (OR717505 and OR743536-OR743560), and a BLAST search of the GenBank database revealed 100% (927/927) homology with E. amylovora strain CP066796.1. The housekeeping gene rpoB was PCR amplified with primers CM7-F and CM31b-R (Rezzonico et al. 2012), and the products were sequenced (PP465516-PP465541). BLAST analysis showed 100% (944/944 nt) and 96.19% (908/944 nt) identities with the sequences of E. amylovora ATCC 15580 CP066796.1 and E. pyrifoliae CP201486 CP103445.1, respectively. To fulfill Koch's postulates, SA strains were inoculated on five healthy 3-month-old clones of apple (Malus domestica cv. Gala) per strain with a 10-µl bacterial suspension containing 107 colony-forming units per milliliter by injecting directly in the veins of the upper second leaf plus 5 healthy plants injected with sterile distilled water as control. Plants were incubated at 28°C for six days under a 12-hour light regime. Observed symptoms were similar to the ones observed in the field. The experiment was replicated twice. Bacterial colonies on CCT media were re-isolated from the inoculated apple rootstocks and confirmed by the A/B primer set. To our knowledge, this is the first peer-reviewed report of E. amylovora in SA since the fire blight-like symptoms were observed in SA in 2013 (Alhudaib, 2013). Further research will identify new host plants for the fire blight pathogen within SA which is important due to the importation of pome fruit seedlings (quince, apple, and pear) from neighboring Jordan where E. aylovora was reported (Tehabsim et al. 1992).

First Report of Rhizopus arrhizus (syn. R. oryzae) causing Sunflower Head Rot in Arizona, USA.

Sunflower (Helianthus annuus) is an ornamental, edible-seed, and important oil source plant in the USA. In June 2023, head rot was observed in sunflowers grown in an experimental field at Yuma County Cooperative Extension, University of Arizona, AZ (32°42'35.5"N, 114°42'25.0"W). The disease incidence was of >70%. Head lesions were dark-brown and extended through the head to the bracts and stem. White to gray mycelia and black sporangia-like structures were also observed on sunflower heads. Symptomatic plants (n =10) were sampled to determine the disease causing agent. Five symptomatic tissues for each plant (0.5 to 1 cm) were submitted to surface sterilization by dipping in 75% ethanol 2min, 1% NaOCl for 2 mins and rinsing with sterile water. Once sterilized, the tissues were plated on potato dextrose agar (PDA) plates and incubated at 25±0.2 °C. After two days, hyaline mycelia were observed on PDA which turned white after 7 days. A total of 50 isolates were obtained, of which ten were randomly selected and purified by the hyphal-tip method and later used for morphological analysis. Microscopic observations revealed hyaline and aseptate hyphae, sporangiophores measuring 900 to 1.2000 µm in length and dark-brown sporangium (72 to 144 µm, mean = 90). The columella was sub-globose, and the sporangiospores ranged from 7.29 to 9.37 µm in size (mean = 7.5 µm). The morphological characteristics described above were similar for the ten isolates and were in accordance with the species R. arrhizus as described by (Gryganskyi et al. 2018). Genomic DNA was extracted from three randomly chosen isolates using The DNeasy Plant kit (Qiagen) and used for further molecular identification. The internal transcribed spacer (ITS) region was amplified using ITS1/ITS4 primers (White et al. 1990) and then Sanger sequenced. The sequences shared 100% nucleotide identity with each other (GenBank accession numbers PP747852, PP747853 and PP747854) and shared 100% identity to R. arrhizus GenBank accessions (MT316366.1, MN547407.1). One isolate, YPHC-94-A, was randomly selected for Phylogenetics and Pathogenicity analyses. Phylogenetics analysis based on sequence data of ITS showed that the isolated YPHC-94-A clustered together with R. arrhizus species (Zhang. 2023). Pathogenicity test was conducted by inoculating four sunflower varieties (American giant, Lemon queen, Solar eclipse and Mammoth) (n = 12 for each variety). Plant heads were inoculated with a disc of mycelia (0.5 cm2) and incubated for 24 h at 30 ±2 °C and 94% RH. Five uninoculated plants of each variety were used as controls. Head rot symptoms were observed within 3-5 days on inoculated plant post inoculation depending on the variety, whereas the control plants stayed asymptomatic. R. arrhizus was re-isolated from all the inoculated plants and was morphologically and molecularly identical to the field isolates, thus fulfilling Koch's postulates. R. arrhizus has already been reported in different US regions (Sanogo et al. 2010), however, to the best of our knowledge this is the first report in Arizona. Due the high disease incidence and pathogen aggressiveness found in the environmental conditions of the U.S southwest desert, we consider sunflower Head rot a potential risk for sunflower production in Arizona as well as the large population of wild sunflowers in the State.

First report of leaf spot caused by Paramyrothecium roridum on Coffea arabica in Hawai'i, USA.

During the 2022-2023 season, the harvested coffee crop in Hawai'i (Coffea arabica) was valued at $57.1 million (USDA NASS 2023). In September 2022, coffee leaf samples with foliar leaf spots affecting the Kona Typica variety were collected from Honaunau, Hawai'i, incidence <10%. The symptoms were circular, necrotic leaf spots with yellow margins, which merged, resulting in complete leaf blade coverage and subsequent leaf drop. Sporodochia were present on the abaxial leaf surface. Symptomatic leaf tissue was disinfected in 10% bleach solution for 60 seconds and chlorotic leaf tissue from the spot margins were excised and placed onto water agar and potato dextrose agar (PDA; Difco, USA). After a 7-day incubation period, pure cultures with white aerial mycelium having sporodochia arranged in concentric rings with olivaceous to black conidial masses were isolated. The conidia were aseptate, hyaline, smooth, cylindrical with rounded ends, measuring 5.1 to 6.8 µm long and 1.7 to 2.3 µm wide (n=50). Based on symptomology and cultural/morphological characteristics (Huaman-Pilco et al. 2023; Lombard et al. 2016; Pelayo-Sanchez et al. 2017), the isolates were initially identified as Paramyrothecium roridum (Tode) L. Lombard & Crous, comb. nov. (syn. Myrothecium roridum Tode). Fungal identification of isolate P22-81-2 was further confirmed using BLAST analysis of bulk sequenced PCR products of the ribosomal DNA internal transcribed spacer (ITS) region (White et al. 1990), ß-tubulin (ßtub), RNA polymerase II (RPB2), and calmodulin genes (Lombard et al., 2016; Huaman-Pilco et al., 2023). The gene sequences (GenBank accession nos. PP211198, PQ192517-19) were >98.4% identical to the P. roridum type specimen (CBS 357.89). A multilocus maximum likelihood phylogenetic analysis incorporating sequence data from previous relevant studies (Lombard et al., 2016; Pinruan et al. 2022) confirmed species identification. To prove pathogenicity, four, 26-month-old Kona Typica variety seedlings were foliar inoculated with a 1 X 106 conidia/ml suspension using a perfume atomizer. An additional four plants were inoculated in a similar manner with sterile water which served as controls. All plants were sprayed to drip on both the upper and lower leaf surfaces and incubated in a clear plastic bag to keep the humidity levels between 90 to 100% for 48 hours at 24°C. After 48 hours, the plants were removed from the bags, placed on a greenhouse bench, and observed weekly for symptom development. Within seven days light brown sunken spots had developed on all inoculated plants. The spots continued to enlarge having a dark distinct margin, light tan center, chlorotic halo, and formed concentric rings, which were identical to the original diseased samples. Leaf spots were not present on any of the control plants. The test was conducted twice. A fungus was consistently reisolated from the leaf spot margins of inoculated plants and morphologically (PDA) and molecularly (ITS, ßtub, RPB2, calmodulin) identified as P. roridum, thus fulfilling Koch's Postulates. To the best of our knowledge, this is the first report of P. roridum causing leafspots on C. arabica plants in Hawai'i. This pathogen has been reported on coffee in other parts of the world including Colombia, Costa Rica, Guatemala, Puerto Rico, and Mexico (USDA Fungus-Host Database). Under the right conditions, P. roridum has the potential to cause leafspots and defoliation resulting in economic losses for coffee growers in Hawai'i.

First Report of Phytophthora cinnamomi causing root rot of avocado trees in Greece.

In September 2023, thirty declining 30-year-old avocado (Persea americana) trees ('Hass' grafted on 'Zutano' seedlings) were detected in a 1.5-ha orchard in the island of Crete (Chania region). Crown symptoms encompassed wilting and leaf chlorosis, advancing to defoliation and extensive dieback. Tap and feeder roots decayed and brown discoloration of root tissues was evident on heavily infected trees. The disease was severe and widespread, resulting in a 5% mortality rate among 300 trees. The pathogen was isolated with a modified soil baiting technique (Ferguson and Jeffers, 1999). Surface disinfected avocado fruits were immersed in water containing soil samples. Following a period of 2 to 8 days, tissue fragments from the resulting necrotic lesions on the fruit surface were transferred on ΡΑRP medium and subsequently incubated at 20°C (Ferguson and Jeffers, 1999). Three isolates (AV2, AV12 and AV11a) were obtained by transferring single hyphal tips to new Petri dishes containing V8 juice agar. They were grown at 20˚C and used for identification after 10 days. Isolates formed coralloid colonies with abundant clustered spherical hyphal swellings and terminal or intercalary (ratio 1:5) thick-walled chlamydospores measuring 20 to 36 µm (avg 29±0.8 µm) with characteristic thick walls (avg 1.2±0.2 µm). Sporangia, produced in non-sterile soil-extract water, were ovoid to obpyriform, persistent, non-papillate, 32 to 81 µm (avg 56±4.8 µm) long and 20 to 42 µm (avg 31±3.2 µm) wide (n=100). Isolates were heterothallic as they did not produce oospores in single cultures. Based on the morphological traits the isolates were identified as Phytophthora cinnamomi (Erwin and Ribeiro 1996). The internal transcribe spacer region (ITS) including ITS1, 5.8S rDNA region, and ITS2 as well as the cytochrome c oxidase subunit I (coxI) gene of the three representative isolates wereamplified with ITS1/ITS4 and FM83/FM84 primers, respectively (White et al. 1990; Martin and Tooley 2003), and sequenced (GenBank acc. PP506613 to PP506615 and PQ063867 to PQ063869, respectively). BLAST search revealed almost 100% identity with the sequences of P. cinnamomi ex-isotype isolate (KC478663 and KU899315 respectively). Pathogenicity tests using isolate AV2 were conducted following the soil infestation method (Jung et al. 1996) using six-year-old avocado 'Zutano' seedlings. Six non-inoculated plants treated with vermiculite-multivitamin juice mixture were used as controls. Plants (1 m tall) were grown in pots under greenhouse conditions and watered regularly. Six weeks post inoculation, all inoculated trees showed chlorosis, wilting and root rot, while control plants remained symptomless. Symptoms were similar to those observed in the field and the pathogen was re-isolated and molecularly identified as previously described. This study presents the first documented occurrence of P. cinnamomi, widely regarded as the most destructive avocado pathogen globally, on avocado crops in Greece (Rodger et al. 2019). Additionally, this marks the first recorded presence of this pathogen on the island of Crete, regardless of the host species. The accurate identification of Phytophthora species associated with avocado root rot is essential for implementing an effective disease management strategy, particularly in the selection of appropriate disease-resistant rootstocks.

First Report of Stem Blight of Mungbean (Vigna radiata) Caused by Diaporthe longicolla in the United States.

Mungbean (Vigna radiata) is primarily grown in Asia and directly consumed by humans. U.S. consumers embraced mungbean as a plant-based protein in vegan eggs and meat substitutes. New cultivars are being developed for American farmers because of the crop's tolerance to heat and drought, and its adaptability to current farming infrastructure. Mungbean's short season complements various cropping systems such as intercropping, alternative cropping, and green manure. With rotations and inclusion with soybean systems, there is a concern about the overlap of common pathogens for soybean and mungbean. During August 2022 when mungbeans reached full maturity (growth stage R6), reddish-brown and necrotic stem lesions with linear rows of black pycnidia were observed on Berken and OK2000 cultivars at fields located in Hancock County, IA and Story County, IA in the United States. Pycnidia measured 0.5-0.6mm in length. Disease incidence was approximately 10% of plants in Hancock County, IA and less than 3% of plants in Story County, IA. Pycnidia from 16 plants were excised and immersed in a 0.5% NaOCl solution for 1 min, rinsed with autoclaved distilled water, and placed onto potato dextrose agar (PDA). Eighteen isolates were hyphal tipped and grown on PDA and were stored at 25°C. Isolates were then visually identified by culture and conidia morphology (Hobbs et al. 1985, Santos et al. 2011). Colonies were cream to white, dense, and floccose. Large black stromata were formed in a concentric pattern or scattered; alpha conidia were ellipsoidal. Template DNA for PCR amplification of the internal transcribed spacer region of the nuclear ribosomal DNA operon (ITS) and the beta-tubulin gene (TUB) was extracted from 18 isolates by scraping mycelia with a sterile pipette tip and transferring it into 50 ul of PrepMan Ultra Sample Reagent (Applied Biosystems, Foster City, California, USA). Fungal primers were ITS1 and ITS4 (White et al. 1990) and Bt-2F/Bt-2R (Udayanga et al. 2014). Sequences of isolates obtained from fields in both counties were identical, providing no species diversity. GenBank accession numbers for the ITS region were PP105598 and PP105599; PP108254 and PP108255 for TUB sequences. BLAST results showed the ITS 550/550 base pairs with type specimen D. longicolla ATCC 60326 GB NR_144924 and the TUB 446/446 base pairs with type specimen D. longicolla ATCC 60325 GB KJ610883. Thus, the isolates were identified as Diaporthe longicolla (Hobbs) J.M. Santos, Vrandecic & A.J.L. Phillips based on morphology and molecular characters (Santo et al 2011; Udayanga et al. 2014). To confirm the pathogenicity of the D. longicolla isolates, twenty mungbean plants (cv. Berken and OK2000) were grown in the greenhouse at 85% RH and 16hr light for 20 days. Inoculum was prepared by placing sterile toothpicks on 1/3 PDA with a single representative isolate from each field location for 21 days (Ghimire et al. 2019). Mungbean plants were grown in a 10cm-by-10cm pot containing a greenhouse professional growing mix (Sungrow, Agawam, Massachusetts, USA) and grown for 30 days post emergence. After 12 days of growing, a 3mm segment of the infested toothpick was inserted into a stem wound below the first trifoliate and sealed with parafilm. A sterile toothpick was inserted into the control plants. After 14 days, red lesions extended downward 1 to 3 cm from the inoculation site, and white mycelial was present in the wound. At 21 days red lesions spanned 3 to 9 cm upward and downward from the inoculation site. Pycnidia were present on collapsed stem tissue, and leaves became chlorotic. Damage was limited to 2mm from the mock-inoculation site, with no discoloration in the control plants. Symptomatic tissues were plated and compared to the original isolates. Alpha conidia were ellipsoidal with the base end rounded. To our knowledge, this is the first report of Diaporthe longicolla causing disease on mungbean within the U.S. and worldwide. The presence of this disease in two locations suggests the potential for Diaporthe longicolla to be a serious disease of mungbean in the future.

First report of Colletotrichum plurivorum and Colletotrichum truncatum causing anthracnose on melon plants in Brazil.

Melon (Cucumis melo L.) is an economically important crop in Brazil, with an annual production of 699.281 tons (FAO 2024). Fungal diseases are one of the biggest problems in melon production, and melon growers in northeastern Brazil have reported over 80% of plants showing anthracnose symptoms in the fields during rainy seasons. Plants were wilted, displaying brown necrotic lesions and water-soaked spots with yellowish edges on the leaves and vines. Melon fruits displayed necrotic lesions on the outside. From June 2022 to June 2023, melon leaves (varieties Yellow, Galia, and Cantaloupe) from anthracnose-symptomatic plants were collected in four melon farms located in the municipalities of Afonso Bezerra, Mossoró, Tibau, and Upanema in the state of Rio Grande do Norte. Small fragments of symptomatic leaves were disinfected in 70% ethanol (30 sec) and 2.5 % sodium hypochlorite (1 min), rinsed in sterile distilled water, and plated on PDA Petri dishes with tetracycline (0.05g/liter). Plates were maintained in a bio-oxygen demand incubator (BOD) for 3 days at 28 ± 2 °C, under a 12 hr photoperiod. Eleven representative fungal colonies resembling Colletotrichum spp. were selected and monosporically grown on PDA for seven days for morphology, pathogenicity, and molecular analyses.ight colonies showed pinkish-dark brown with acervuli in the center and cottony mycelium, and showing black edges in some isolates, resembling C. plurivorum (Zhang et al. 2023). Conidia from those colonies were hyaline, cylindrical with obtuse ends, and 17.76 x 7.06 µm, n= 50. Three colonies developed pinkish-gray mycelia with numerous black microsclerotia, and the conidia were hyaline, falcate, and 27.38 x 4.10 µm, n= 50, resembling C. truncatum (Yu et al. 2023). The total DNA of the eleven isolates was extracted, and the internal transcribed space (ITS), glyceraldehyde 3-phosphate dehydrogenase (GAPDH), actin (ACT), ß-tubulin (TUB), and chitin synthase 1 (CHS-1) regions were partially amplified by PCR. Amplicons were sequenced and deposited to Genbank (Table eXtra1). A phylogenetic tree was built with the Maximum likelihood method with the concatenated sequences of the five partial gene sequences on Software MEGA (Version 11.0.10) (Tamura et al. 2021). The isolates CML5, CML8, CML9, CML10, CML11, CML14, CML15, and CML25 were grouped with Colletotrichum plurivorum CBS 125474 (orchidearum complex), and the isolates CML26, CML27 and CML28 with Colletotrichum truncatum CBS 15:35 (truncatum complex) with 87 % e 97 % of Bootstrap support, respectively. C. plurivorum was detected in four farms visited (we selected two representative isolates per farm), while C. truncatum isolates were all from the farm in Afonso Bezerra municipality. A pathogenicity test was performed following the method of Baishuan et al. (2023), micro-injuries were made in leaves of melon seedlings 'Goldex Yellow' and inoculated with a spore suspension of colonies with seven days of growth (106 spore/mL) of each isolate and sprayed to the point of dripping. Sterile water was used as mock. After nine days, anthracnose symptoms similar to those observed in the field were seen in all inoculated leaves, while no symptom was observed in the leaves of the mock plants. The pathogens were reisolated and their identification was confirmed by morphology and sequencing. Five seedlings were inoculated per isolate and mock, the assay was repeated, and the same results were observed. The species C. plurivorum has already been reported to cause disease in Cucumbers in Brazil (Silva et al. 2023) and C. plurivorum and C. truncatum in Citrullus lanatus in China (Guo et al. 2022). To the best of our knowledge, this is the first report of C. plurivorum and C. truncatum causing anthracnose in melon plants in Brazil.

Occurrence of Maize Leaf Spot Disease Caused by Leptosphaerulina australis in Yunnan, China.

Maize (Zea mays) is vital as a staple food and livestock feed crop. Yunnan is one of the main maize-producing provinces in China (National Bureau of Statistics, 2022). While corn production in Yunnan is lower than the national average, the development of drought-tolerant varieties has contributed to improving productivity. In August 2021, a new leaf spot disease on maize was observed in Lancang, Yunnan (22°26'38.11"N to 22°48'38.68"N, 99°48'15.13"E to 99°59'20.03"E), causing serious damages to maize production with incidence up to 76.19 %. Initially, small light yellow lesions were seen scattered on diseased maize leaves, round or polygon, measuring 0.3 to 2.0 cm in diameter. In the intermediate phase, these lesions sank, ruptured, and turned white with dark brown borders. In severe cases, they merged into large irregular patches, reaching up to 10 cm, leading to complete leaf necrosis. Small black ascomata were seen on the lesions. Tissue sections reveal perithecium embedded in leaves, measuring 94~145 µm in diameter. Symptomatic tissues were sterilized in 1.5% NaClO for 60s, and washed twice withsterile purified water, then plated on potato dextrose agar (PDA) at 25℃, 90% relative humidity (RH), and a 12-hour light cycle. 6 isolates were obtained from 2 diseased maize cultivars. In 20 days, the colony reached the edge of the PDA plate, the center darkening from white, featuring white aerial mycelium on top and black on the reverse side. Brown ascomata, solitary or clustered, measured 80.1~176.7 × 55.57~138.9 µm. The ellipsoid to oblong ascospores were 17.9~39.7 × 10.9~14.1 µm, and the bitunicate, thick-walled asci were 90.1~133.3 × 26.6~33.5 µm. The genomic DNA was extracted using the Chelex-100 method (Möller et al. 1992). For molecular identification, the ITS, LSU, and ß-tubulin (Tub2) genes were amplified using primer pairs ITS1/ITS4 (White et al. 1990), LR0R/LR5 (Vilgalys et al. 1990) and Btub2Fd/Btub4Rd (Woudenberg et al. 2009), respectively. Sequencing was performed by Sangon Biotech (Shanghai) Co., Ltd. The sequenced loci (GenBank accession nos.: LSU, OL687348-53; ITS, OL617009-10, and OL664058-61; Tub2, OL741678-83) of the isolates exhibited 100%/ 99%/ 100% similarities with L. australis genes: LSU, MH868885; ITS, KF381084; Tub2, GU237541, respectively. Using MEGA 11.0, phylogenetic trees were constructed using the maximum-likelihood algorithm on concatenated sequences of LSU, ITS, and Tub2 for isolates LCMB1 to 6. The isolates clustered with two L. australis strains with 100 % bootstrap support (1,000 replicates). The results were consistent with the Bayesian Inference tree. The pathogenicity test used strain LCMB4 on six healthy maize plants during the heading period under natural conditions. Three leaves pre-plant were wounded with sterile sandpaper and sprayed with conidial suspension (106 spores ml-1, diluted in sterilized water) in the greenhouse at 28℃, 90% RH, and a 12-hour light cycle, with sterilized distilled water used for control. Inoculated leaves developed symptoms consistent with the described after 10 days, while control leaves remained symptomless. The same pathogen was re-isolated from the infected leaves, fulfilling Koch's postulates. Previously, L. australis has been isolated from turfgrass (Mitkowski et al. 2004), Alfalfa (Zhang et al. 2021), soil (Li et al. 2018), and Paris polyphylla var. chinensis (Fu et al. 2019), but not from maize. This is the first report of L. australis causing leaf spot on maize globally.

First Report of Strawberry Anthracnose Crown Rot Caused by Colletotrichum siamense in New England.

In the summer of 2023, the Connecticut Agricultural Experiment Station was contacted by a farm in southern Connecticut due to reports of strawberry (Fragaria × ananassa) plants showing signs of severe wilting and crown rot across multiple fields, covering ~20 hectares. Cut crowns from diseased plants had marbled red and white lesions typically associated with anthracnose crown rot (ACR). Symptomatic plants were collected from five June-bearing cultivars (cvs. AC Valley Sunset, Lyla, Dickens, and Allstar) spanning four non-adjacent fields with incidence ranging from 5-90% and severity ranging mild wilting in low incidence fields to severe wilting/mortality in high incidence fields. Internal tissue from diseased crowns was surface sterilized in 0.6% NaOCL for 3 minutes, rinsed with sterile water, and plated on potato dextrose agar. After one-week, hyphal tips of fungi were transferred to fresh plates which formed dense mycelial mats of fluffy, greyish-white hyphae. Orange spore masses formed near the center of the colonies, each of which contained numerous cylindrical and fusiform straight conidia, matching spores within the genus Colletotrichum (De Silva et al. 2019). Average conidia (n=192) length was 15.7 ± 1.6 µm and width was 5.4 ± 0.7 µm. Fungi matching this morphology were isolated from 83% of the collected symptomatic crowns and hyphae were collected from two isolates, CT5-1 and CT23-1, for DNA extraction using the GeneJET Plant Genomic DNA Purification Kit. PCR was performed using primers targeting actin (ACT), calmodulin (CAL), ß-tubulin (TUB2), GAPDH (gpdA), and ITS, followed by Sanger sequencing, which yielded identical sequences for both isolates (CT5-1 Accessions numbers: PP002078-81, OR999066)(Carbone and Kohn 1999; Hassan et al. 2018; Templeton et al. 1992). These were combined with sequences from fourteen Colletotrichum genomes, all of which were aligned, trimmed, and concatenated using Mega11 (Tamura, Stecher, and Kumar 2021). Model selection was conducted using IQ-TREE and selected parameters were used to generate maximum-likelihood trees from all five loci individually and the concatenated sequence, all of which placed the isolates in a high confidence cluster with Colletotrichum siamense (Nguyen et al. 2015). To confirm the pathogenicity of the pathogen, strawberry plants (cv. Jewel) (n=5) five weeks after bare root transplant were infected. The base of each crown was penetrated 5 mm deep with a sterile 20 µL pipette tip and then inoculated with 10 µL of spores at a concentration of 106 spores/mL. Control plants (n=5) were inoculated with 10 µL of sterile water. Plants were maintained at 30°C day (16-hour)/20°C night (8-hour) in a growth chamber and assessed after 14-days. Four of the five inoculated plants had visible wilt symptoms and bisected crowns revealed the marbled red and white lesions typifying ACR. Control plants had no clear wilting and bisected crowns were visibly healthy. C. siamense re-isolated from infected tissue presented with identical hyphal /spore morphology and ITS/Tub2 were re-amplified and sequenced, yielding identical sequences to CT5-1. Plant inoculations with the same variety were repeated, yielding identical symptom development and crown lesions. C. siamense has been a dominant source of ACR throughout the southeastern US but has not previously been a major problem in the Northeast. Given the extent of the field infection, it is likely that these isolates can survive the colder winter temperatures of New England, but further experimentation is necessary to determine the extent of the pathogen's winter hardiness.

First report of Apple bitter rot caused by Colletotrichum godetiae in Ontario.

Bitter rot is an emerging disease of apple (Malus domestica) fruit in Ontario in part due to changing weather conditions. The disease was mostly documented in warm and humid regions such as the southern USA, and Central and South America. Thirteen Ontario orchards in the fall of 2019 and 15 in 2020 were scouted for bitter rot based on their previous history of the disease. 100 fruit were collected from ten asymptomatic trees per cultivar and two susceptible cultivars, 'Empire' and 'Ambrosia' were scouted per orchard. If an orchard did not have either one of these cultivars, 'Honeycrisp' or 'Gala' were used. The fruit was stored at 4-5 oC for five months and then left at 22 oC for two weeks and assessed thereafter for bitter rot symptoms. Monoconidial cultures of Colletrotrichum spp. were established from the symptomatic fruit using potato dextrose agar media with antibiotics at 22 oC 14-hour light cycles. The fungal isolates were divided into two groups based on colony morphology observations seven days after culturing. The first group showed light grey, cottony, aerial mycelium on top and a pink to dark red color on the reverse of the plate. The second group showed light to dark grey, cottony mycelium on top and dark green colonies on the reverse of the plate. It is difficult to identify Colletrotricuhum species solely based on morphology, therefore the representative isolates from each group were used for multilocus gene sequencing and species identification. Genomic DNA was extracted using the Qiagen DNeasy Plant Mini Kit according to the manufacturer's protocols. The ITS region was amplified and sequenced using the primers ITS-1F (Grades & Bruns 1993) and ITS-4 (White et al. 1990). Primers T1 and T2 (O'Donnell & Cigelnik 1997) were used to amplify and sequence the 750 bp region of the TUB gene. Primers GDF1 and GDR1 (Guerber et. al. 2003) were used to amplify a 280 bp region of the GADPH gene. Following an NCBI nucleotide blast search, the isolates from group 1 were identified as C. fioriniae.The ITS sequences of group 2 isolates were matched 100% to the Colletotrichum godetiae type strain CBS133.44 and they were 99% matched to the closest species C. Johnstonii CBS128532. The TUB sequences matched 100% identity to 20 sequences belonging to C. godetiae, 99.59 % identity to C. godetiae type strain CBS133.44, and 97.75% to C. Johnstonii CBS128532. The GADPH sequences matched with 100% identity to C. godetiae ON241087.1 or MT816329.1 and 99-99.5% identity to the type strain CBS133.44 and 98.61-99% identity to CBS128532. Based on the blast results the group 2 isolates were identified as C. godetiae and their sequences were submitted to GenBank with ID OP702962 for ITS and OP972240 and OP972241 for GADPH and OP972242 for the TUB gene. Out of 50 isolates collected in this work, 94% belonged to group 1 and 6% belonged to group 2. Koch's postulates were performed on selected isolates by artificial inoculation of 5 healthy detached fruits of the cultivar, 'Empire.' Fruit surfaces were wiped with 70% ethanol, dried, wounded with a sterile needle, and then inoculated with a 10 µl of spore suspension containing 1x10^6 spores /ml. Inoculated fruits were incubated in a humid chamber at 22°C in dark. Symptoms started to appear at 5 days post-inoculation and looked like small brown circular lesions which developed orange spore masses as they grew into larger lesions. The non-inoculated control fruit did not develop lesions. Fungal colonies were established from the spores collected from the inoculated fruit and found to have identical morphological characteristics to the original isolates. C. godetiae has previously been reported to cause bitter rot in apples from various countries in Europe (Baroncelli et al. 2014; Munda, 2014; Wenneker et al. 2016). C. fioriniae has previously been reported as the dominant species causing bitter rot in apples although other species including C. chrysophilum and C. noveboracense have also been reported as causal agents from the Eastern USA (Khodadadi et al. 2020). To the best of our knowledge, this is the first report of Colletotrichum godetiae causing the bitter rot of apples in Ontario, Canada.

First Report of Fusarium proliferatum Causing Bulb Rot on Lilium davidii var. willmottiae in China.

Lilium davidii var. willmottiae, known as Lanzhou lily, is widely cultivated in China for its edible bulbs. In July 2023, symptoms of bulb rot were observed on Lanzhou lilies harvested from Lanzhou, Gansu Province, during storage at the Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences (Beijing, China), at an incidence of nearly 70%. The surface of the lily scales had dark water-stained spots, after the development of which the color gradually darkened, the bulbs became soft, accompanied by a pungent smell. Finally, the whole bulb became ruined and rotten, and there were thick mycelium layers on the bulbs. The infected bulbs were washed with clean water, sterilized with 75% ethanol for 30 s and 2% sodium hypochlorite for 5 min, and then rinsed three times with sterile distilled water. The 5 mm×5 mm tissue pieces from the junction of the diseased part and the healthy part were clipped, placed on potato dextrose agar (PDA) medium and subsequently incubated at 25 °C. Pure cultures were obtained by transferring hyphal tips to new PDA plates. A total of 10 fungal isolates were obtained, all of which exhibited typical Fusarium characteristics. The colonies were white to pink with white to cream-colored aerial mycelia. After 10 to 15 days of incubation, the macroconidia (n = 50) were hyaline, relatively slender with a curve, three to five septate, and 8.73 to 33.24 × 2.16 to 4.19 µm in length. The microconidia (n = 50) were hyaline and pyriform, without septa, and measured 4.04 to 8.48 × 1.24 to 2.65 µm. These morphological characteristics were similar to those described for Fusarium proliferatum (Leslie and Summerell 2006). For molecular identification, a cetyltrimethylammonium bromide (CTAB) protocol was used to extract total genomic DNA (O'Donnell et al., 1998), after which the internal transcribed spacer (ITS), translation elongation factor subunit 1-alpha (TEF1-α) and RNA polymerase Ⅱ subunit 2 (RPB2) genes were amplified using the universal primers ITS1/ITS4, EF1/EF2 and RPB2-5f2/fRPB2-7cr, respectively, and subsequently sequenced (White et al., 1990; O'Donnell et al., 1998; Liu et al., 1999; Reeb et al., 2004; O'Donnell et al., 2007; Jiang et al., 2018). The sequences of a representative isolate (CAAS01) were analyzed and submitted to GenBank under accession numbers OR554007 (ITS), OR594233 (TEF1-α) and OR603932 (RPB2). A BLAST analysis revealed that the sequences of the ITS, TEF1-α, and RPB2 genes shared 100%, 100%, and 100% identity, respectively, with those of Fusarium proliferatum (MT466521.1, MK952792.1, and LT841266.1) in GenBank. In addition, the ITS, TEF1-α and RPB2 sequences shared 100%, 100%, and 100% identity with those of Fusarium annulatum (LC13675, the Fusarium fujikuroi species complex; previously known as the Gibberella fujikuroi species complex) in the Fusarium-ID database. Fusarium proliferatum, whose common synonyms are Gibberella fujikuroi mating population D and Gibberella fujikuroi var. intermedia, is the anamorphic form of the Gibberella fujikuroi complex that belongs to the Nectriaceae family. A phylogenetic tree was constructed based on the combined TEF1-α and RPB2 sequences of CAAS01 and other Fusarium isolates, revealing that CAAS01 was grouped with Fusarium proliferatum. Based on sequence alignment and phylogenetic analysis, the isolate was identified as Fusarium proliferatum. To determine the pathogenicity of the isolated fungi, healthy bulbs were punctured with disposable sterilized needles and soaked in equal amounts of sterile water and conidial suspension (1×107 conidia/mL) for 30 min respectively. The pathogenicity experiment was repeated three times. After 7 days of inoculation at 25 °C and 80% relative humidity, the surface of the inoculated bulbs produced water-stained spots and mycelium layers consistent with the symptoms exhibited by Lilium davidii var. willmottiae bulbs during storage, while the uninoculated lily bulbs remained symptomless. Fusarium proliferatum was reisolated from the infected bulbs and identified based on morphological and molecular characteristics, fulfilling Koch's postulates. To our knowledge, this is the first report of bulb rot on Lilium davidii var. willmottiae caused by Fusarium proliferatum in China. This study will contribute to the development of management strategies for this postharvest disease in Lilium davidii var. willmottiae.

First Report of Anthracnose Caused by Colletotrichum siamense on Machilus thunbergii Siebold & Zucc. in South Korea.

Machilus thunbergii Siebold & Zucc., known as Japanese bay tree, is an evergreen tree distributed widely in East Asia, including South Korea, where the species is of ecological importance. Machilus thunbergii provides habitat for wildlife species and is a common urban tree. In September 2022, anthracnose symptoms on leaves were observed in Jeju (33°26'02.4"N, 126°19'48.8"E) and Tongyeong (34°49'27.1"N, 128°24'01.8"E) in South Korea. Disease incidence on leaves of each affected tree, naturally growing in an urban forest area covering approximately 0.5 ha was approximately ~ 70 % in each study area. Anthracnose symptoms that were observed on 70 to 80% leaves per tree in each study area included orbicular or irregular, whitish-grey spots on leaves that were 1.5 to 3.0 cm in diam. In some cases where leaves were severely affected, larger blotches were formed, leading to bleaching symptoms and eventually defoliation. For pathogen isolation, two or three leaves showing anthracnose symptoms from each of the 15 trees were randomly selected and brought to the laboratory. Fungal isolations were then directly made by transferring spores from acervuli that developed on diseased leaves onto potato dextrose agar (PDA) media. Cushion shaped acervuli filled with salmon to orange-colored conidial masses were produced on media approximately two weeks after the incubation at 25 ± 1°C with a photoperiod of 12 h. Conidia were single celled, hyaline, cylindrical with rounded ends, smooth walls, 13.7 to 18.1 µm long and 3.1 to 4.5 µm wide (n=30). Among 15 cultures that were successfully isolated, 10 isolates were retained based on culture characteristics, and two randomly selected monoconidial cultures were deposited in the culture collection (CDH) of the Chungnam National University, Republic of Korea (Accession No. CDH057-58). Two isolates selected, CDH057 and CDH058, were subjected to identification, and this was achieved based on multiplesequence comparisons using on internal transcribed spacer regions of rDNA (ITS1 and ITS2), partial sequences of actin (ACT) and ß-tubulin (TUB2) gene regions amplified using ITS1F / ITS4, ACT-512F / ACT-783R and T1 / Bt2b, respectively (Weir et al. 2012). The representative sequence data were deposited in GenBank under the accession numbers OR473277 and OR473278 for the ITS, OR480772 and OR480773 for ACT, and OR480774 and OR480775 for TUB2. The resulting sequences were further used for a phylogenetic analysis based on the maximum likelihood method using a concatenated dataset of the ITS, ACT and TUB2 gene sequences for Colletotrichum species in the C. gloeosporioides clade. The results showed that the pathogen isolated in this study clustered with Colletotrichum siamense (Vouchered specimens: MFLU 090230, COUFPI291, and COUFPI294) (Prihastuti et al. 2009). Sequence comparisons revealed that the isolates obtained in this study differed from the type species of C. siamense (MFLU 090230; FJ972613 for ITS, FJ 907423 for ACT, FJ907438 for TUB2) at 2 of 258 bp (∼0.8%) and 6 of 387 bp (∼1.6%) in the ACT and TUB2 sequences, respectively, while the ITS was identical to the type species. For pathogenicity tests, a total of ten three-year-old seedlings of M. thunbergii were used. The leaves of each tree were sprayed with 5 ml of conidial suspension (105 conidia/ml, isolate CDH057). Three control plants were sprayed with sterile water. After being sprayed, treated areas were sealed with a plastic bag for 24 hours to preserve humidity. Anthracnose symptoms, identical to those observed in the field, appeared five to seven days after the inoculations, while no symptoms were observed on control plants. The isolates used in the pathogenicity test were reisolated from 90% of lesions, and their identity was confirmed based on sequence comparisons, thus fulfilling Koch's postulates. Species of the C. gloeosporioides species complex include important plant pathogens, particularly C. siamense, which cause significant losses of economic and ecological relevance on a wide range of hosts (~ 100 hosts) (Talhinhas and Baroncelli 2021). Although C. fioriniae in the C. acutatum species complex, was found on M. thunbergii in South Korea (Thao et al. 2023), anthracnose associated with C. siamense on M. thunbergii has not been reported in the country. In this regard, this is the first report of anthracnose caused by C. siamense on M. thunbergii in South Korea. To effectively control the disease, more attention should be paid on the host range of the pathogen and other regions where the disease caused by the pathogen might occur in the country.

First Report of Fusarium falciforme Causing Root and Rhizome Rot of Epimedium sagittatum in China.

Epimedium sagittatum (Sieb.et Zucc.) Maxim., a perennial herb, is an important medicinal plant, rich in flavonoids, and widely used in the treatment of sexual dysfunction, rheumatic disease, and cancers (Tan et al. 2016). In July 2022, a disease of root and rhizome was found on E. sagittatum aged 1-8 years in a planting area (266 ha) of Zhumadian City (32°58'12" N, 114°37'48" E), Henan Province, China. The disease incidence per field (660 m2) was around 10-15% in six randomly surveyed fields planted with about 10,000 E. sagittatum plants each. Symptoms included leaf yellowing, root and rhizome browning, rotting and necrosis, and eventually the whole plant wilted and died. Fifteen plants with symptoms were sampled to isolate the pathogen. Symptomatic tissues were cut into small pieces of 5×5 mm, surface sterilized with 75% ethanol for 30 s, followed by three rinses with sterile double-distilled water (ddH2O). The pieces were then surface disinfected with 0.1% HgCl2 for 30 s, rinsed three times with sterile ddH2O, placed onto potato dextrose agar (PDA) plates and incubated at 28°C in the dark for 5 days. Twelve deferent Fusarium spp. colonies were purified by excising hyphal tip onto PDA for cultivation. Pathogenicity test of all strains was performed. Only isolate GY2 could result in root and rhizome rot of host plant. Colonies of GY2 on PDA had abundant white aerial mycelia with yellow halo. Macroconidia were hyaline, falciform, with a slightly curved apical cell and blunt basal cell, 29.7~45.0 (average 38.3) × 4.5~6.6 (average 5.3) µm (n =50), with 2-3 septa. Microconidia were oval, or reniform, hyaline, 8.4~26.5 (average 16.5) × 2.7~6.0 (average 4.5) µm (n =50), with 0-2 septa. Morphological characteristics of isolate GY2 were consistent with those of the Fusarium solani species complex (FSSC) (Chehri et al. 2015). For molecular identification, a region of the translation elongation factor 1-α (TEF) and RNA polymerase second largest subunit (RPB2) of GY2 were PCR-amplified and sequenced using the primers EF1-728F/986R (Carbone et al. 1999) and RPB2-5f2/7cr (O'Donnell et al. 2010), respectively. The TEF and RPB2 sequences (GenBank accession nos. OR978135.1 and OR978136.1) of GY2 were concatenated for a phylogenetic analysis using the Bayesian method (Zhang et al. 2020). The phylogenetic tree revealed that isolate GY2 clustered with F. falciforme with a credibility value of 99%. Morphological and molecular results support identification of isolate GY2 as F. falciforme. A pathogenicity test was performed on 4-year-old healthy plants grown in pots. Twenty healthy plants were inoculated by pouring a 200 mL conidial suspension (1×106 conidia/mL) around the rhizome. Control plants received 200 mL of sterile ddH2O. All treatments were maintained in a greenhouse at 25±1°C and 80% relative humidity. The assay was conducted three times. After 20 days, similar symptoms as those in the field were observed on the inoculated plants, whereas controls remained asymptomatic. Fusarium falciforme was reisolated from the symptomatic plants and showed the same morphological and molecular characteristics as isolate GY2, fulfilling Koch's postulates. Fusarium falciforme was reported to cause root rot of tobacco (Qiu et al. 2023) and industrial hemp (Paugh et al. 2022). However, this is the first report of F. falciforme causing root and rhizome rot of E. sagittatum. Our study will contribute to the development of strategies for the effective management of this disease on E. sagittatum.

Pathological characterization and management of Lasiodiplodia theobromae, a hemi-biotroph with an interkingdom host range.

Heart rot disease, caused by Lasiodiplodia theobromae, is destructive for date palms and other woody plants. The disease was reported in several oasis in Egypt, and the pathogen was found in association with infected trees suffering die-back and rachis blight. Seven phylogenetically distinct fungal isolates were selected, and their pathogenicity was confirmed on date palms. The isolates exhibited variable degrees of virulence on inoculated leaves, which confirms the variation. We examined the antifungal effect of microbial bioagents and plant extracts on heart rot disease. The isolates of Trichoderma spp. gave moderate reduction of the pathogen's linear growth (40-60%), while their exudates were ultimately ineffective. Bacillus spp. isolates, except for B. megaterium, were more effective against spore germination as they gave 80-90% reduction on average. Among the examined plant extracts garlic sap gave 98.67% reduction of linear growth followed by artemisia (15.5%) and camphor (24.8%). The extraction methods greatly influenced the antifungal efficiency of each extract as exposure to organic solvents significantly decreased the efficiency of all extracts, while hot water extraction negatively affected garlic sap only. Successful bioagents and plant extracts were further assayed for the suppression of heart rot disease on date palms. Both T. album and T. harzianum gave comparable degrees of suppression as by commercial fungicides. In addition, treatment before or during pathogen inoculation was the most effective as it significantly enhanced the expression of defense-related enzymes. Our findings suggest bio-pesticides possessing a dual role in disease suppression and defense boosters for date palms suffering heart rot disease.

Construction of an infectious clone of citrus chlorotic dwarf-associated virus and confirmation of its pathogenicity.

Citrus chlorotic dwarf disease (CCDD) seriously affects the citrus industry. Citrus chlorotic dwarf-associated virus (CCDaV) is speculated to be the causal agent of CCDD. However, this speculation has not been confirmed by fulfilling Koch's postulates. In this study, an infectious clone was constructed that comprises a 1.6-fold tandem CCDaV genome in the binary vector pBinPLUS and agro-inoculated into Eureka lemon (Citrus limon) seedlings through vacuum infiltration. At 60 days post inoculation, 25% of the Eureka lemon seedlings developed symptoms of crinkling and curling that are the same as those associated with the wild-type virus. Western blotting and graft transmission assays confirmed that the infectious clone systemically infected Eureka lemon seedlings. In addition, CCDaV can establish infection on three more Citrus species and one hybrid, although at different infection rates. These findings support that CCDaV is the primary causal agent of CCDD. The infectious CCDaV clone will allow further studies on the functions of viral proteins and molecular interactions of CCDaV with its hosts.

First Report of Golovinomyces bolayi Causing Powdery Mildew on Lettuce in Mexico.

In August 2022, powdery mildew symptoms were detected on lettuce (Lactuca sativa) in a commercial field located in Quecholac, Puebla, Mexico. Signs appeared as whitish powdery masses on leaves. Disease incidence was about 100% and signs covered up to 40% of leaf surface. Mycelium was amphigenous forming white patches. Hyphal appressoria were indistinct or nipple-shaped and solitary. Conidiophores (n= 30) were hyaline, erect, arising from the upper surface of hyphal mother cells or lateral, and of 90 to 201 µm long. Foot cells were cylindrical, of 49 to 92 × 10-15 µm, followed by 1-3 shorter cells, and forming conidia in chains. Conidia (n= 100) were hyaline, ellipsoid-ovoid, doliiform-subcylindrical, 27 to 40 × 14 to 20 µm. Conidial germination belonging to the Euoidium type. Chasmothecia were not observed. The morphological characters were consistent with those of Golovinomyces bolayi (Braun et al. 2019). A voucher specimen was deposited in the Herbarium of the Department of Agricultural Parasitology at the Chapingo Autonomous University under accession number UACH451. To confirm the identification of the fungus, genomic DNA was extracted from conidia and mycelium following the CTAB method (Doyle and Doyle 1990), and the internal transcribed spacer (ITS) region was amplified by PCR using the primers ITS5/ITS4 (White et al. 1990) and sequenced. The resulting 506 bp sequence had 100% identity to those of G. bolayi (LC417109 and LC417106). Phylogenetic analyses using the Maximum Likelihood and Maximum Parsimony methods were performed and confirmed the results obtained in the morphological analysis. The isolate UACH451 grouped in a clade with isolates of G. bolayi. The ITS sequence was deposited in GenBank under accession number OR467546. Pathogenicity was confirmed by gently dusting conidia onto ten leaves of healthy lettuce plants. Five non-inoculated leaves served as controls. The plants were maintained in a greenhouse at 25 to 30 ºC, and relative humidity of 70%. All inoculated leaves developed similar symptoms to the original observation after 10 days, whereas control leaves remained disease free. Microscopic examination of the fungus on inoculated leaves showed that it was morphologically identical to that originally observed. Based on morphological data and phylogenetic analysis, the fungus was identified as G. bolayi. This pathogen has been previously reported causing powdery mildew on lettuce in Argentina, Canada, Chile, Ecuador, Peru, USA and Venezuela (Braun et al. 2019; Mieslerová et al. 2020). To our knowledge, this is the first report of G. bolayi causing powdery mildew on lettuce in Mexico.

First Report of Chocolate Spot Caused by Botrytis eucalypti on Faba bean in China.

Faba bean (Vicia faba) is one of the characteristic economic crops in Qinghai Province of China, which has multiple uses as grain, vegetable, fodder, fertilizer and medicine. Chocolate spot is a critical disease of faba bean in the world, and it is widely spread in all production areas of Qinghai. In August 2021, a severe occurrence of chocolate spot was found in a faba bean field in Xunhua County, Qinghai Province (35°52'N, 102°22'E, alt. 1890m). All plants in the field were affected by this disease. A voucher specimen was deposited in the Herbarium of Plant Pathology, College of Agricultural and Forestry Sciences at Qinghai University under accession No. PY015. The pathogen infected the leaves and stems, causing small irregular red spots to appear, which later coalesce into larger spots and faded green lesions appear around the spots. Diseased leaf pieces 5 mm2 were surface sterilized with 75% ethyl alcohol for 30s, 1.2% NaOCl for 30s, and rinsed three times with sterile water. They were then plated on potato dextrose agar (PDA) at 22℃ for 10 days in the dark. Fungal colonies are initially white, then gray, and have produced spores by 5 days. Conidia are clusters, ellipsoidal or ovoid, 9-14 × 6-9 µm. The conidiophore is straight, terminally enlarged, septate, 300-1500 µm long, 8-13 µm wide. No sclerotia were observed during culture. DNA of the strain PY015 was extracted by CTAB method. Molecular identification was first performed using the universal region of ITS (ITS1/ITS4). The PCR product was sequenced, the sequence was deposited in GenBank under the accession number OR739575. The results showed 100% similarity to Botrytis spp. (KX301016, MT250940, LC519322) in BLAST search. Molecular characterization was continued using five specific primer pairs: RPB2 (DNA-dependent RNA polymerase subunit II, RPB2-5F/RPB2-7cR), NEP1 and NEP2 (necrosis and ethylene-inducing proteins, NEP1for/ NEP1revB and NEP2forD/NEP2revD), HSP60 (heat-shock protein 60, HSP60for/HSP60rev), G3PDH (glyceraldehyde-3-phosphate dehydrogenase, G3PDHfor/G3PDHrev). The sequences of PY015 were deposited in GenBank (accession numbers: OR731179, OR731180, OR731181, OR731182, OR731183), and all five sequences showed 100% similarity to Botrytis eucalypti YZU171088 (accession numbers: MH614610 MH614611, MH614612, MH614613 MH614614). A phylogenetic tree based on these five genes was constructed using Mega7.0 (1000 bootstrap replicates, neighbor-joining method), and PY015 was placed in the same clade as YZU171088 with 100% bootstrap values. Morphological and molecular biological results confirmed that isolate PY015 was B. eucalypti. To fulfill Koch's postulates, the spore suspension (2 × 105 conidia/ml) was sprayed on healthy faba bean (Yun-122) plants at the 10-leaf stage, while an equal amount of sterile distilled water was applied to controls. After 7 days, the inoculated plants showed symptoms consistent with field infection and B. eucalypti was re-isolated using the same protocol, while the control remained asymptomatic. The pathogenicity test was repeated twice. The same isolates were recovered from symptomatic leaves and identified by NEP1 sequence. B. eucalypti was morphologically and molecularly identical to the original isolates, completing Koch's postulates. Currently, Botrytis fabae, Botrytis fabiopsis, and Botrytis cinerea are the main pathogens of chocolate spot on faba bean that have been identified and reported nationally and internationally. B. eucalypti is a new species discovered from eucalyptus in southern China in 2016, and its current hosts are only eucalyptus and citrus. To our knowledge, the present study is the first report of chocolate spot caused by B. eucalypti on faba bean in China.

First report of leaf blight caused by Nigrospora hainanensis on Euonymus japonicus in China.

Euonymus japonicus Thunb., belonging to the family Celastreace and native to East Asia, is a widely cultivated evergreen ornamental woody plant with important ecological and economic values. In May 2023, serious leaf blight of E. japonicus occurred in the campus green space at Guiyang University, Guizhou Province, China (26°55'85"N, 106°78'04"E). Early symptom appeared as small, circular light brown spots on the edges or tips of the leaves. Then, the spot developed visible necrosis, initially light brown to dark brown halos with clear margins. Subsequently, severely infected leaves appear totally wilt, and significantly decrease their ornamental values. In a 0.07-ha field, the disease incidence reached to 40-55%. To identify the pathogen, ten typical symptomatic E. japonicus leaves were collected. They were initially immersed in 75% ethanol for 3 min, and by sodium hypochlorite (4% NaClO) solution for 45 s, and ultimately rinsed with sterile distilled water (dH2O) five times for not less than 1 min each time, then, placed the leaves on potato dextrose agar (PDA) medium and cultured for 5 days at 25°C in constant temperature incubator. Cultures were purified to yield eight isolates. Early colonies are white and regularly rounded, gradually turning dark brown to black with fluffy mycelium. Conidia were single celled, smooth, black, spherical or ellipsoidal. The conidia size of the representative strain, GY-2 and GY-3, was averagely 12.3-17.3 µm × 10.8-17 µm (n = 50). The conidiogenous cells were monoblastic, hyaline, globose or ampulliform. Morphology-based identification revealed the strain as Nigrospora spp. (Wang et al., 2017). For further confirmation, PCR of GY-2 and GY-3 DNA was performed with the primers ITS1/ITS4 (White et al., 1990), Bt2a-F/Bt2b-R (Glass and Don-aldson 1995), and TEF1-728F/TEF1-986R (Carbone and Kohn 1999). Sequences of the ITS region, TUB and TEF1 genes from the strain GY-2 and GY-3 were deposited in GenBank. (GY-2: OR999377, PP112221 and PP150467; GY-3: PP406871, PP421045 and PP421046, respectively). BLAST analysis showed GY-2 100%, 100%, and 98.36%; GY-3 99.43%, 98.21% and 100% (ITS region, TEF1, and TUB) identity to N. hainanensis sequences (accession numbers. NR_153480.1, KY019415.1, and KY019464.1; KX986094.1, OP611475.1, and KY019597.1). Additionally, tandem sequences of ITS, TUB and TEF1 constructed by MEGA 7.0 confimed the homology through the phylogenetic tree. Pathogenicity tests were conducted on healthy plants grown, each 5 mm diameter of active growing mycelium plug of isolate GY-2 was attached to 15 leaves from five healthy 2-year-old E. japonicu plants. The same number of leaves in the control group were treated with non-inoculated plugs only. All the plants were incubated at 25°C and 75% relative humidity with a 16-h/8-h photoperiod. After 10 days, no symptoms appeared on the leaves of the control group. In contrast, symptomatic blight appeared on all leaves inoculated with GY-2. Pathogenicity tests were performed five times. Pure strains were re-isolated from diseased leaves and, confirmed to be N. hainanensis based on the above methods. Recently, Nigrospora oryzae was reported as causal agent of leaf spots on Euonymus japonicus in China (Xu et al., 2023). To our knowledge, this study is the first report of N. hainanensis causing leaf blight on E. japonicu. Identification of the etiological agent may provide assistance for sustainable management in the future.