Influence of hybrid class and ensiling duration on deoxynivalenol accumulation and its derivative deoxynivalenol-3-glucoside while ensiling corn for silage.

In silage corn (Zea mays L.), Fusarium graminearum causes diseases and produces the mycotoxin deoxynivalenol (DON). The work presented here investigated DON accumulation and its fate during the ensiling of ground, whole-plant material obtained from dual-purpose (DP) and brown midrib (BMR) corn hybrids. Multi-year field trials arranged in a randomized complete block design were conducted in Wisconsin to evaluate BMR and DP corn hybrids in response to fungicide treatment. At harvest, the samples were chopped and vacuum sealed for a mini-silo time series assessment with silos opened following anaerobic fermentation for 0, 30, 60, 90 and 120 days. Repeated measures analysis of ensiled corn showed that hybrid (P < 0.01) and ensiling duration (P < 0.01) significantly impacted DON concentration through ensiling, while fungicide treatment had no significant effect (P > 0.05). Across hybrids and treatments, DON concentrations detected at harvest were the lowest with DON3G at harvest significantly (P < 0.01) and highly correlated (r = 0.74) with DON concentration 30-days post ensiling. These findings suggest that mycotoxin testing in corn should include not only DON but also for conjugates of DON that can be metabolized back to DON and increase the final DON concentration during ensiling.

First Report of Uromyces aecidiiformis Causing Rust Disease on Fritillaria unibracteata in China.

Fritillaria unibracteata Hsiao et K. C. Hsia is a recognized source of 'Chuanbeimu' in the 'Chinese Pharmacopoeia'. In China, its bulbs have been used as a traditional herbal cough remedy for about 2,000 years. Surveys for fungal diseases were conducted in Xiaojin and Songpan, Sichuan Province, the primary cultivation region of F. unibracteata, with an area of 150 acres, in May and July 2022. Rust was found in almost all areas and incidence ranged from 5% to 80% in all study areas. Diseased leaves displayed yellow spots on the upper side, and raised buff, golden, or fuscous waxy pustules on the lower side. In severe cases, the infection extended to the stems and petioles, leading to wilting and death of plant. Spermogonia, aecia, and telia were mainly found on the underside of leaves. Spermogonia were scattered among the aecia and exhibited a range of colors from honey-yellow to chestnut-brown. They had a cross-sectional diameter of 94.4 to 214.3 µm height and 94.2 to 197.5 µm in width (n=30). They were nearly spherical, embedded in the host tissue, and had distinct periphysis at the pores. Aecia were hemispherical, initially white, with the peridium later turning yellowish-brown and opening via a central pore. Aeciospores were pale yellow, finely and closely verrucose, measuring 20.6 to 34.1 × 18.4 to 30.1 µm with a cell wall thickness of 1.5 to 2.4 µm (n=51). Prior to plants wilting, elongated telia were observed, gradually exposed, then finally opening through longitudinal cracks in the epidermis. Teliospores were unicellular, dark brown, oblong to oval, and solitary on stems, measuring 24.7 to 38.2 × 19.2 to 27.8 µm (n=130) with a wall thickness of 1.6 to 3.1 µm, with a low hyaline papilla at the apex and were moderately rugose with longitudinal parallel ridges. The characteristics align with previous descriptions of Uromyces aecidiiformi (Rees, 1917, Zhuang, 2005). The primer pair LR0R (Moncalvo et al., 1995)/LR5 (Vilgalys & Hester, 1990) was utilized for amplifying and sequencing the large subunit of the nuclear ribosomal RNA genes from strains IS909-3 and IS1816 (GenBank PQ008482, PQ008483). The obtained sequences showed a high similarity of 99.9% to 100% similarity to strains U1023 and UBC19 of U. aecidiiformis in RustHubb (KR0014142 and PUN23000)( Kaishian et al., 2024). Through examination of morphology, host range, and sequence similarity, we determined the rust species to be U. aecidiiformis. Pathogenicity testing was conducted by spraying a suspension of aeciospores (1×105 spores/mL in 0.05% Tween 20 solution) on six healthy four-year-old F. unibracteata plants indoors in May 2023. The plants were allowed to grow under natural conditions, where the diurnal temperature ranged from 9 to 20℃, with an average temperature of 14℃, which is conducive to the growth of F. unibracteata. Another six seedlings were sprayed with 0.05% Tween 20 solution as controls. After three weeks, all infected plants showed symptoms similar to those seen in the field, while control plants remained symptom-free. Microscopic examination and sequencing confirmed that the pathogen morphology was consistent between the field and the inoculation, meeting Koch's postulates. Although U. aecidiiformis has been previously reported to cause rust of F. pallidiflora and F. ussuriensis(Zhuang, 1989, Zhuang, 2005), this is the first report of U. aecidiiformis causing rust on F. unibracteata in China. This pathogen significantly reduces the yield and quality of Chuanbeimu, highlighting the importance of effectively identifying and controlling it.

First report of Curvularia spicifera (≡ Bipolaris spicifera) causing spathe blight and leaf spot disease of pearl millet (Cenchrus americanus) in India.

Cenchrus americanus (L.) Morrone (Poaceae), is an important millet crop cultivated mainly in arid and semiarid regions and is a staple food grain for millions of people. During 2021 July surveys in the pearl millet fields in Mysore (12°30'55" N; 76°56'54" E), Karnataka, India, plants showed spathe blight and leaf spot disease with an overall incidence ranging from 5 - 8% in the 15 hectares surveyed. Infected leaves appeared brown, and lesions extended to the sheath. Some spathes were also found infected with similar symptoms. Diseased leaves and spathes were collected (n = 5 each) for pathogen identification. Samples were cut into small pieces (0.5 cm2), sterilized with sodium hypochlorite (2%, v/v), and blotted dried. The associated fungal pathogen was isolated on potato dextrose agar (PDA) medium amended with Streptomycin (40 mg/L) and incubated at 28 ºC for 1 week. Colonies were grey, fluffy, cottony with an irregular margin, undulate and dark brown in the back of the plate. Conidiophores were pale brown, erect, slightly curved, septate, unbranched, verruculose and measured 27.1 - 94 µm in length × 2.3 - 4.5 µm in width (n = 20). Conidiogenous cells were brown, subcylindrical, irregularly shaped, and conidia were straight, mainly elliptical, dark brown smooth, with two to three septa, with measurements of 11.1 - 26.4 µm by 5.7 - 14.3 µm (n = 50). Based on morphological characters, the pathogen was identified as Curvularia sp. Two representative isolates (UOMPM1 & UOMPM2) were molecularly identified. The total genomic DNA was extracted with a CTAB method, and ITS, GAPDH and tef-1α loci were amplified using primers ITS1/ITS4 (White et al., 1990), GPD1/GPD2 (Berbee et al., 1999) and EF1983F/EF-2218R (Schoch et al., 2009) respectively. ITS sequence had 100% similarity (706/706bp) with reference sequence C. spicifera (MH863648; HF934915 & HF934916); tef-1α sequence had 100% (933/933bp) identity with C. spicifera (KM062878, KJ939505), and the GAPDH sequence was 99.8% identical to that of Curvularia sp. (MG979055), and C. spicifera (MH809681). Combined dataset of concatenated sequence (ITS-GAPDH-tef-1α) was used in a phylogenetic analysis and revealed that the isolates were in a common clade with the isolate of Curvularia spicifera (CBS 274.52) thus, confirming the identity of the isolated pathogen as C. spicifera. The sequences obtained in the present study were deposited in the GenBank (ITS: OQ253406, OQ253407; LSU: OQ253429, OQ253430; GAPDH: OQ263372, OQ263373 & TEF: OQ263374, OQ263375). Pathogenicity test was carried out by inoculating (foliar /whole plant spray) 60 healthy pearl millet plants (45-days old), grown in field plot with spore suspension (105 conidia/ml). Control plants (n=20) were treated with sterile water. The experiments were conducted in triplicates and repeated twice. Development of disease symptoms was recorded on 41 plants, and all control plants remained healthy. The identity was confirmed after re-isolation as C. spicifera based on cultural and molecular sequence analysis. To our knowledge, this is the first report of C. spicifera causing a leaf spot and spathe blight disease of pearl millet in India. This disease seriously affects grain production, and effective disease management strategies need to be investigated.

Associations Among Cultivar Cropping Sequence, 2,4-Diacetlyphloroglucinol-Producing Pseudomonad Populations, and Take-All Disease of Winter Wheat in Oregon.

Take-all of wheat (Triticum aestivum L.), caused by Gaeumannomyces tritici (syn. G. graminis var. tritici), is perhaps the most important soil-borne disease of wheat globally and can cause substantial yield losses under several cropping scenarios in Oregon. Though resistance to take-all has not been identified in hexaploid wheat, continuous cropping of wheat for several years can reduce take-all severity through the development of suppressive soils, a process called "take-all decline" (TAD). Extensive work has shown that TAD is driven primarily by members of the Pseudomonas fluorescens complex that produce 2,4-diacetlyphloroglucinol (DAPG), an antibiotic that is associated with antagonism and induced host resistance against multiple pathogens. Field experiments were conducted to determine the influence of agronomically relevant first year wheat cultivars on take-all levels and ability to accumulate DAPG-producing pseudomonads within their rhizospheres in second-year field trials and in greenhouse trials. One first year wheat cultivar consistently resulted in less take-all in second-year wheat and accumulated significantly more DAPG-producing pseudomonads than other cultivars, suggesting a potential mechanism for take-all reduction associated with that cultivar. An intermediate level of take-all suppression in other other cultivars was not clearly associated with population size of DAPG-producing pseudomonads, however. The first year cultivar effect on take-all dominated in subsequent plantings, and its impact was not specific to the first year cultivar. Our results confirm that wheat cultivars may be used to suppress take-all when deployed appropriately over cropping seasons, an approach that is cost effective, sustainable, and currently being utilized by some wheat growers in Oregon to reduce take-all.

Wireworm species associated with corn and soybean agroecosystems in Ontario, Canada.

Wireworms, the larvae of click beetles (Coleoptera: Elateridae), are often the target of insecticide seed treatments commonly used in corn (Zea mays L.) and soybean (Glycine max (L.) Merr.) production in North America. Nevertheless, there is a lack of knowledge of the species, life history, and economic impact of wireworms present in these agroecosystems. An extensive survey of wireworms was conducted in corn and soybean fields in Ontario, Canada, from 2014 to 2017 to document species distribution and co-occurrence and to identify risk factors related to their abundance. In total, 4,332 specimens were collected from 1,245 different sampling records. The dominant species collected was Limonius agonus (Say) (Coleoptera: Elateridae) comprising 71.5% of the specimens. The remaining wireworm specimens were identified as Hypnoidus abbreviatus (Say), Melanotus similis (Kirby), M. cribulosus (LeConte), M. depressus (Melsheimer), M. communis (Gyllenhal), Agriotes mancus (Say), Aeolus mellillus (Say), and Hemicrepidius spp (Germar). Multiple wireworm species were found to commonly occur within the same field and the same sample. Path analysis was conducted to investigate whether site, soil, and agronomic characteristics influenced wireworm distribution and abundance. Several significant relationships were found between wireworm species and geographic factors, soil texture, and agronomic practices. The results of this survey provide critical information that can be used to improve integrated pest management of the major wireworm genera found in corn and soybean agroecosystems in Ontario.

Unconventional Strategies for Aphid Management in Sorghum.

Since the invasion of the sorghum aphid Melanaphis sorghi (Theobald), farmers in the sorghum (Sorghum bicolor L. Moench) production region in the Great Plains of the U.S. have faced significant crop damage and reduced yields. One widely used practice to aid in managing sorghum aphids is pest monitoring, which often results in field-level insecticide applications when an economic threshold is reached. However, relying on this traditional management practice includes the application of insecticides to non-infested plants. To reduce insecticide usage in sorghum, we proposed spraying individual plants when aphids are present or absent compared to traditional spraying based on a standard economic threshold using field replicate plots over two summer seasons. The experimental results of this study indicated fewer aphids in plots managed with an economic threshold, followed by randomly sprayed and plant-specific treatments compared with the untreated control treatment. Therefore, compared with traditional management, those treatments can be alternative strategies for managing aphids on sorghum within our field plot study.

Occurrence of Fusarium Crown Rot Caused by Fusarium culmorum on Winter Wheat in Xinjiang Uygur Autonomous Region, China.

Wheat (Triticum aestivum L.) is the predominant grain crop and plays a pivotal role in grain production in Xinjiang Uygur Autonomous Region (XUAR), China. Its cultivated area constitutes approximately half of the total sown area of grain crops in XUAR, with 1.14 million hectares in 2021. Fusarium crown rot (FCR) of wheat, caused by Fusarium culmorum (W.G. Smith) Sacc., is one of the most devastating soil-borne diseases known to seriously reduce grain yield (Ma et al. 2024; Saad et al. 2023). In 2016, FCR of wheat, caused by F. culmorum, was firstly identified in Henan Province, China (Li et al. 2016). In June 2023, during the investigation of FCR of wheat in Aksu Prefecture, XUAR, FCR on winter wheat (cv. Xindong 20) was found (82.761349°E, 41.612202°N). The grain-filling period for winter wheat in early June coincided with a period of high temperatures and water demand in Aksu Prefecture. Approximately 8% of the Xindong 20 wheat plants exhibited symptoms of white heads and browning at the stem base, with the disease present in 82% of the wheat fields surveyed. To identify the pathogens, 20 samples of diseased stem basal tissue, each 0.5 cm in length, were collected and sterilized with 75% alcohol for 30s and 5% NaOCl solution for 2 min, followed by three rinses with sterile water. These samples were then plated onto potato dextrose agar (PDA) medium at 25°C for 5 days. A total of 17 isolates with consistent morphological characteristics were obtained using single-spore technique, with an isolation rate of 85%. The isolated strains exhibited rapid growth on PDA, producing fluffy, pale-yellow hyphae, and accumulating a pale-yellow to dark red pigment on the bottom of the medium. On carnation leaf agar (CLA), these strains formed orange colonies due to the aggregation of a large number of macroconidia. The macroconidia were short and thick, with three to four septa and rounded apical cell, averaging 31.94 to 40.96 × 5.62 to 6.71 µm (Magnification of ×400). Microconidia were not observed. These morphological characters were consistent with those of F. culmorum (Leslie and Summerell. 2006). Two isolates (D-9 and D-11) were selected for molecular identification. The EF-1α gene fragment was amplified using primers EF1/EF2 (5'-ATGGGTAAGGARGACAAGAC-3'/5'-GGARGTACCAGTSATCATG-3') as previously described by O'Donnell et al. (1998). The two 665 bp PCR products were sequenced and submitted to GenBank (GenBank Accession No: PP763247 and PP763248) with 99. 7% identity to the published F. culmorum sequences (e.g., OP985478, OP985477, MG195126, KX702638). The molecular identification was further confirmed by F. culmorum species-specific PCR primers FcOIF/FcOIR (Nicholson et al. 1998). The expected PCR products of 553 bp were produced only in F. culmorum. Strains D-9 and D-11 were used to conduct the pathogenicity experiment on 7-day-old winter wheat (cv. Xindong 20) using drip in the lower stem inoculation method with a 10-µl of 106 macroconidia ml-1 suspension, and the control 7-day-old winter wheat were treated with sterile water (Xu et al. 2017). The experiments were replicated five times in a greenhouse at temperatures ranging from 20℃ to 25℃. After 4 weeks, all inoculated wheat seedlings showed stem base browning or even death. No symptoms were observed on the control plants. The fungus was reisolated from all inoculated wheat plants by the method described above and identified by morphological and PCR amplification using F. culmorum species-specific primers FcOIF/FcOIR. No F. culmorum was isolated from the control wheat plants, fulfilling Koch's postulates. To the best of our knowledge, this is the first report of F.culmorum causing FCR on winter wheat in XUAR, China. Considering wheat is the predominant grain crop and plays a pivotal role in grain production in China, necessary measures should be taken to prevent the spread of F. culmorum to other regions.

Occurrence and management of the emerging pathogen Epicoccum sorghinum.

Epicoccum sorghinum is a notorious fungal pathogen that causes leaf spot symptoms on a wide range of plants, leading to devastating losses in crop production and quality. Here, all reports regarding the occurrence and management of E. sorghinum are covered for the first time. E. sorghinum has been detected in tropical and subtropical climate areas during the rainy season, mainly from March to August, since 2016. Although E. sorghinum shows broad host spectrum, the disease incidence is especially notorious in cereal crops and ornamental plants, suggesting that these plants are especially susceptible. Control methods based on synthetic fungicides, plant extracts, and microbial biocontrol agents have been reported. However, most agents were applied using only in vitro conditions, restricting the information about their actual applicability in field conditions. Additionally, E. sorghinum can colonize cereal grains and synthesize the carcinogenic mycotoxin tenuazonic acid, posing an enormous hazard for human health. Furthermore, although E. sorghinum is an emerging pathogen that is currently causing yield penalties in important crops, there is lack of information about its pathogenic mechanisms and virulence factors, and there is currently no commercial antifungal agent to manage E. sorghinum. Collectively, it is imperative to conduct in vivo studies to determine the efficacy of antifungal agents and the most effective methods of application in order to develop suitable management strategies against E. sorghinum.

First Report of Xanthomonas euvesicatoria pv. sesami Causing Leaf Spot on Sesame (Sesamum indicum L.) in South Carolina, USA.

Sesame (Sesamum indicum L.) is an annual plant known as one of the first domesticated oilseed crops. It is cultivated worldwide, mostly in Asia, Africa, and the Americas (Singh, 2006). In August 2022 and September 2023, dark angular necrotic spots on leaves and stems (100% incidence), blights, and severe defoliation were observed in a 4-acre rainfed sesame field located in the Colleton County of South Carolina, USA (Fig. S1). Bacterial streaming from cut leaf lesions was observed from diseased plants in both years. Two plants were collected for pathogen isolation in 2023. Symptomatic leaves were surface sterilized with 70% ethanol for 1 min and dried in a laminar flow hood. For each isolate, four sterile toothpicks were used to poke lesion margins and stirred in 300 µl of sterile distilled water in a 2-ml sterile microcentrifuge tube and soaked at room temperature (c. 21 °C) for 10 min. Each bacterial suspension (10 µl) was streaked on nutrient agar (NA) in a Petri dish. Convex and mucoid yellow colonies formed after a 48-h incubation at 28°C in the dark. Two isolates (S813 and S814), one from each plant, were obtained by transferring single colonies to new NA plates. Both isolates were preliminarily identified as Xanthomonas [S813: X. campestris (P = 0.53); S814: X. campestris (P = 0.77)] using a Biolog Microbial Identification System (GEN III Microplate; Identification Database v.2.8.0.15G). PCR amplification of the atpD and dnaK genes was performed for both isolates using the conditions described in Félix-Gastélum et al. (2019). The sequences of both amplicons are 100% identical for each gene between the two isolates. PCR and sequencing of the gyrB gene was also done for S813 with the primers from Young et al. (2008). The atpD (S813/S814), dnaK (S813/S814), and gyrB (S813) sequences (GenBank accessions: PP507118 to PP507120) showed the best match with 100% identity to the corresponding gene sequences [GenBank accessions: KJ491167 (100% coverage), KJ491257 (99% coverage), EU285201 (100% coverage)] of the X. euvesicatoria pv. sesami (=X. campestris pv. sesami) type strain LMG865 (Constantin et al. 2015, Parkinson et al. 2009). A neighbor joining tree with the concatenated sequences of these three genes (2,210 nt) showed that S813 and LMG 865 had the closet relationship with X. euvesicatoria pv. alfalfae (CFBP3836, Fig. S2). To fulfill Koch's postulates, three healthy sesame plants (cultivar Shirogoma) were spray inoculated separately with each suspension of S813 and S814 in sterile tap water until runoff (approx. 5×108 CFU/ml). Two sesame plants were sprayed with sterile tap water and served as negative control. All plants were maintained in a greenhouse at approximately 28/20°C (day/night) with natural photoperiod. Dark leaf spots and leaf yellowing were observed on inoculated plants 7 to 14 days after inoculation. No disease symptom was observed on the control plants. Bacteria were reisolated from leaf spots of the inoculated plants and confirmed to be X. euvesicatoria pv. sesami based on atpD and dnaK sequences. The disease was first reported in Sudan (Sabet and Dowson, 1960), after which it was reported in USA (Isakeit et al., 2012) and Mexico (Félix-Gastélum et al. 2019). To the best of our knowledge, this is the first report of this disease in South Carolina, USA. Since the interest of sesame to the farmers is increasing in the southeastern USA, it is necessary to perform further research to examine the disease distribution and its economic impact.

Sustaining the Yield of Maize, Blackgram, Greengram, Groundnut, Cotton, Sugarcane, and Coconut through the Application of Nutrients and Plant Growth Regulator Mixture.

The foliar application of nutrients and plant growth regulators (PGRs) at critical crop growth periods can improve the yield of field crops. Hence, the present study was conducted to quantify the effects of the combined application of nutrients and PGRs (crop-specific formulation) on maize, blackgram, greengram, groundnut, cotton, sugarcane, and coconut yield. In all the crops except coconut, the treatments included (i) a foliar spray of crop-specific nutrients and PGR combinations and (ii) an unsprayed control. In coconut, the treatments included (i) the root feeding of coconut-specific nutrients and PGR combinations and (ii) an untreated control. Crop-specific nutrient and PGR formulations were sprayed, namely, Tamil Nadu Agricultural University (TNAU) maize maxim 1.5% at the tassel initiation and grain-filling stages of maize, TNAU pulse wonder 1.0% at the peak flowering stage of green gram and black gram, TNAU groundnut-rich 1.0% at the flowering and pod-filling stages of groundnut, TNAU cotton plus 1.25% at the flowering and boll development stages of cotton, and TNAU sugarcane booster 0.5% at 45 days after planting (DAP), 0.75% at 60 DAP, and 1.0% at 75 DAP of sugarcane. The results showed that the foliar application of TNAU maize maxim, TNAU pulse wonder, TNAU groundnut-rich, TNAU cotton plus and TNAU sugarcane booster and the root feeding of TNAU coconut tonic increased the yield of maize, pulses, groundnut, cotton, sugarcane, and coconut, resulting in higher economic returns.

Survey of Heterodera glycines population abundance and virulence phenotypes during 2021-2022 in Heilongjiang Province.

Soybean cyst nematode (SCN), Heterodera glycines, poses a significant threat to global soybean production. Heilongjiang, the largest soybean-producing province in China, contributes over 40% to the country's total yield. This province has much longer history of SCN infestation. To assess the current situation in Heilongjiang, we conducted a survey to determine the SCN population density and virulence phenotypes during 2021-2022 and compared the data with a previous study in 2015. A total of 377 soil samples from 48 counties representing eleven major soybean-planting regions were collected. The prevalence of SCN increased from 55.4% in 2015 to 59% in the current survey. The population densities ranged from 80 to 26,700 eggs and juveniles per 100 cm3 of soil. Virulence phenotypes were evaluated for 60 representative SCN populations using the HG type test, revealing nine different HG types. The most common virulence phenotypes were HG types 7 and 0, accounting for 56.7% and 20% of all SCN populations, respectively. The prevalence of populations with a reproductive index (FI) greater than 10% on PI548316 increased from 64.5% in 2015 to 71.7%. However, the FI on the commonly used resistance sources PI 548402 (Peking) and PI 437654 remained low at 3.3%. These findings highlight the increasing prevalence and changing virulence phenotypes of SCN in Heilongjiang. They also emphasize the importance of rotating soybean varieties with different resistance sources and urgently identifying new sources of resistance to combat SCN.

Evaluation of Compost and Manure Amendments for Suppressing Heterodera glycines Ichinohe, 1952.

Soybean cyst nematode is a major pest of soybean crops, causing significant yield losses and economic impact. Current management strategies primarily rely on resistant varieties, cover crops, and seed treatments. However, there is a growing interest in developing sustainable, ecologically based approaches to integrate SCN risk reduction into soybean production systems. This study aimed to evaluate the efficacy of various compost and manure amendments in suppressing SCN populations and promoting soybean productivity. An in vitro egg hatching assay was conducted to screen the inhibitory effects of different compost and manure extracts on SCN egg hatching. Results indicated that poultry manure, Layer Ash Blend®, and swine manure extracts significantly inhibited SCN hatching compared to other treatments across multiple time points. Greenhouse trials further validated the effectiveness of Layer Manure®, poultry manure, High Carbon Dairy Doo®, and Seed Starter 101® in suppressing SCN cysts, eggs, and juveniles. A field microplot trial confirmed the practical promise of Layer Ash Blend® and poultry manure in SCN management, with significant reductions in SCN populations and increased soybean yields. The study also investigated the impact of these amendments on promoting the population of bacterivorous and frugivorous nematodes, contributing to a biological diverse soil ecosystem. Overall, the results indicate that amending SCN-infested soil with specific compost or manure formulations can effectively suppress nematode populations while improving soybean productivity. These findings contribute to the development of sustainable strategies for SCN management in soybean production systems.

First report of Fusarium verticillioides causing leaf rot on Artemisia argyi in China.

Artemisia argyi is a perennial herb native to East Asia. It is an important traditional Chinese medicinal plant known for its strong flavor and medicinal effects. It is rich in active ingredients and has a wide range of biological activities, including anti-inflammatory, antioxidant, and immune regulation properties. From May to July in 2023, a serious leaf rot outbreak occurred on A. argyi in several farms (approximately 200 acres) in Tanghe county (32°46'44" N, 112°43'13" E), Henan Province, China. The incidence rate reached 65% (n=200). Pale yellow spots (1-2 cm in diameter) first appeared on the leaves, then expanded to form irregular yellowish-brown lesions, eventually causing the entire leaves to wither. Diseased leaves (30) were collected and cut into 5 x 5 mm2 pieces in the areas between infected and healthy tissues. The excised plant tissues were sterilized in 75% ethanol and 1% sodium hypochlorite solution for 30 seconds and one minute, respectively. The tissues were then rinsed with sterile water and placed on potato dextrose agar (PDA) followed by incubating at 25 °C for 3 days. The isolated strains belonged to the genera Fusarium and Alternaria. After pathogenicity verification, 25 purified Fusarium strains were obtained. Three representative strains (AC-Q, AC-X, AC-Y) from different regions were used for further studies. Each strain formed abundant aerial mycelium that was initially white and later developed into purple pigments. Aerial conidiophores were sparsely branched, terminating with verticillate phialides. Macroconidia were slender, straight, and measured 21.8 to 47.5 × 3.1 to 4.4 µm, with two to four septa. Microconidia were clavate and measured 8.31 to 11.6 × 2.1 to 3.5 µm. Morphological characteristics were consistent with the species description of Fusarium verticillioides (Sacc.) Nirenberg 1976 (Leslie and Summerell, 2006). The rDNA internal transcribed spacer (ITS), ß-tubulin gene (tub2), translation elongation factor 1-alpha gene (tef1), calmodulin (cmdA), RNA polymerase II largest subunit (rpb1) and RNA polymerase II second largest subunit (rpb2) were amplified for molecular identification (O'Donnell et al., 2022). The sequences were deposited in GenBank with accession Nos. OR960548, OR960552, OR960555 (ITS), OR972413, OR972414, OR972415 (tub2), OR797685, OR797686, OR797687 (tef1), OR972410, OR972411, OR972412 (cmdA), PP035106, PP035107, PP035108 (rpb1), and PP035109, PP035110, PP035111 (rpb2). BLASTn analysis of AC-Q sequences exhibited 99 to 100% similarity with F. verticillioides sequences (strains CBS 576.78) MT010888 of cmdA, MT0109566 of rpb1, and MT010972 of rpb2. A phylogenetic tree was constructed with concatenated sequences (tub2, tef1, cmdA, rpb1, rpb2), alongside the sequences of the type strains using the neighbor-joining method. The three strains formed a clade with the type strain CBS 576.78 of F. verticillioides, and were separated from other Fusarium spp. These morphological and molecular identifications indicated that the pathogen was F. verticillioides. Pathogenicity was tested on 10 healthy 2-month-old potted seedlings by spraying them with a conidial suspension (106 conidia ml-1), and 5 seedlings were sprayed with sterilized water as a control. The plants were placed in a climate incubator at 28°C and a relative humidity of approximately 90%. Ten days after seedling inoculation, typical lesions were observed on the treated plants, except in the control group. The reisolated strains were identified as F. verticillioides by morphological and molecular characterization, fulfilling Koch's postulates. F. verticillioides is known to cause Fusarium ear rot on maize, as well as diseases on other plants in China such as Brassica rapa (Akram et al., 2020) and Schizonepeta tenuifolia (Li et al., 2024). This is the first report of F. verticillioides causing leaf rot on A. argyi worldwide. Identification of the pathogen is crucial for implementing management approaches to reduce yield losses.

Effects of hybrid, foliar treatments, and infection conditions on bacterial leaf streak of sweet corn.

Bacterial leaf streak (BLS) of corn caused by Xanthomonas vasicola pv. vasculorum was first reported in the United States in 2017. The biology and management of BLS are poorly understood. The objective of this work was to determine the effects of hybrid, foliar treatments, and infection conditions (timing, temperature, inoculation site) on BLS of sweet corn. Field studies were conducted to determine if hybrid or foliar disease management treatments influenced BLS development and yield. Corn leaves were inoculated in plots with X. vasicola pv. vasculorum, and noninoculated plots were used for comparison. The leaf incidence and severity of BLS differed significantly among sweet corn hybrids, suggesting different levels of susceptibility to BLS. Grain yield was significantly reduced (14.7%) by BLS for one hybrid. The corn growth stage at time of infection influenced BLS, with incidence and severity significantly greater following inoculation at stage V6 than V9. Foliar application of Kocide®, LifeGard®, and Kocide®+LifeGard® significantly reduced leaf severity compared to nontreated controls in field studies. Kocide® significantly reduced leaf incidence, but no treatments significantly increased yield vs. controls. In comparisons of inoculation methods in a growth chamber, lesion length on leaves was significantly greater on stalk-inoculated than leaf-inoculated plants. Lesions developed on leaf-inoculated plants only at inoculation sites whereas lesions developed on stalk-inoculated plants on multiple leaves. In controlled environments, lesion length on leaves was significantly greater at 21°C than 27°C and 32°C. This study expands our understanding of factors that influence development and management of BLS of sweet corn.

First report of Stagonosporopsis cucurbitacearum Causing Gummy Stem Blight on Trichosanthes kirilowii Maxim. in China.

Trichosanthes kirilowii Maxim. (Cucurbitaceae), one of the Chinese herbal medicines, is an economically important crop in Anhui Province, China. In recent years, gummy stem blight disease, a major disease of cucurbits, was widespread in many T. kirilowii plantations. The initial symptoms on the naturally infected stems appeared as dark brown water-soaked lesions, and as the disease progressed, vines of T. kirilowii gradually withered. On leaves, brown water-soaked lesions were visible initially, and then lesions enlarged and coalesced, resulting in extensive necrosis of leaves. On fruit, lesions covered with the white mycelium were nearly circular and tan to brown initially. Subsequently, the diseased fruit turned black and rotten commonly known as fruit rot or black rot. A Stagonosporopsis-like organism was consistently isolated from symptomatic stems, leaves and fruits. Fungal isolates were initially white and later turned dark grey or black with woolly to floccose aerial mycelium on PDA medium. Twenty-four isolates from different plantations were selected for further morphological studies. Pycnidia and conidia were formed after inoculating on cucumber fruit for 3 days. Pycnidia were globose to sub-globose, brown, ostiolate and 106.7 to 213.6 µm (average 160.1 µm, n = 50) in diameter. Conidia were hyaline, ellipsoidal, aseptate or one-septate, slightly constricted at the septa, 6.1 to 13.6 × 3.5 to 4.8 µm (average 9.9 × 4.1 µm, n = 50), and contained two or more oil drops. Three different loci of the genomic DNA, including the nuclear ribosome DNA internal transcribed spacer (ITS), RNA polymerase II second-largest subunit (RPB2), and ß-tubulin (TUB2) genes., were amplified using primers ITS1/ITS4 (White et al. 1990), RBP2DF/RBP2DR (Lawrence et al. 2013), and T1/ß-Sandy-R (O' Donnell and Cigelnik 1997; Stukenbrock et al. 2012), respectively and sequenced. A phylogenetic tree was built based on analysis of ITS, RPB2, and TUB2 sequences that deposited in GenBank (MW485497-MW485502 for ITS, MW531661-MW531666 for RPB2, and MW531667-MW531672 for TUB2), using the maximum likelihood method. The phylogenetic tree showed that the isolates fell into a single clade with S. cucurbitacearum. On the basis of morphological and molecular characteristics, the isolates obtained from T. kirilowii were identified as Stagonosporopsis cucurbitacearum. Pathogenicity tests were carried out on stems and leaves of 4-week-old T. kirilowii seedlings and on immature fruit collected from adult T. kirilowii plants. The epidermis, previously injured with a syringe needle, was inoculated with 5-mm-diameter mycelial plugs, and the inoculated areas were then wrapped in water-soaked cotton. Controls were similarly inoculated with agar plugs. The diameters of lesions were measured in two perpendicular directions. Re-isolations from the stem and leaf lesions were performed on the PDA medium. Stagonosporopsis cucurbitacearum, was re-identified based on its colony and conidial characteristics and, therefore, completed Koch's postulates. Gummy stem blight caused by S. cucurbitacearum has been reported in a wide range of hosts, including cucumber, luffa, pumpkin, gourd, muskmelon, cantaloupe, and watermelon (Jiang et al. 2015; Keinath 2011; Zhao et al. 2019). To our knowledge, this is the first report of gummy Stem blight disease on T. kirilowii caused by S. cucurbitacearum in China. The research provides a basis for the development and implementation of effective management strategies. Pathogenicity tests were carried out on stems and leaves of 4-week-old T. kirilowii seedlings and on immature fruits collected from adult T. kirilowii plants. The epidermis, previously injured with a syringe needle, was inoculated with 5-mm-diameter mycelial plugs, and the inoculated areas were then wrapped in water-soaked cotton. Controls were treated similarly but inoculated with agar plugs. Diameters of lesions were measured in two mutually perpendicular directions. Reisolations from the lesions were performed on PDA medium, and was re-identified based on its colony and conidial characteristics to complete Koch's postulates. Gummy stem blight caused by S. cucurbitacearum have been reported in a wide range of hosts, including cucumber, luffa, pumpkin, gourd, muskmelon, cantaloupe, and watermelon (Jiang et al. 2015; Keinath 2011; Zhao et al. 2019). To our knowledge, this is the first report of gummy Stem blight disease on T. kirilowii caused by S. cucurbitacearum in China. The research provides a basis for the development and implementation of effective management strategies.

Early detection of nicosulfuron toxicity and physiological prediction in maize using multi-branch deep learning models and hyperspectral imaging.

The misuse of herbicides in fields can cause severe toxicity in maize, resulting in significant reductions in both yield and quality. Therefore, it is crucial to develop early and efficient methods for assessing herbicide toxicity, protecting maize production, and maintaining the field environment. In this study, we utilized maize crops treated with the widely used nicosulfuron herbicide and their hyperspectral images to develop the HerbiNet model. After 4 d of nicosulfuron treatment, the model achieved an accuracy of 91.37 % in predicting toxicity levels, with correlation coefficient R² values of 0.82 and 0.73 for soil plant analysis development (SPAD) and water content, respectively. Additionally, the model exhibited higher generalizability across datasets from different years and seasons, which significantly surpassed support vector machines, AlexNet, and partial least squares regression models. A lightweight model, HerbiNet-Lite, exhibited significantly low complexity using 18 spectral wavelengths. After 4 d of nicosulfuron treatment, the HerbiNet-Lite model achieved an accuracy of 87.93 % for toxicity prediction and R² values of 0.80 and 0.71 for SPAD and water content, respectively, while significantly reducing overfitting. Overall, this study provides an innovative approach for the early and accurate detection of nicosulfuron toxicity within maize fields.

First Report of Clonostachys rosea Causing Bulb Rot on Fritillaria taipaiensis in China.

Taibai Beimu (Fritillaria taipaiensis) is a species of Fritillaria commonly used in traditional Chinese medicine for its antitussive, expectorant, and antihypertensive properties. In April of 2021 and 2022, an incidence 10-30% of yellowing or purpling, wilting, and dying symptoms was observed on Taibai Beimu in Wanyuan, Sichuan province. Infected roots and bulbs displayed spots ranging from brown to black, along with necrotic rot. In severe cases, the entire bulbs rotted. Fifteen symptomatic bulbs were cut into 0.5 × 0.5 cm pieces, surface sterilized in 75% ethanol for 30 s and 1% sodium hypochlorite for 3 min under aseptic conditions, rinsed with sterile water 3 times, and air-dried. The segments were placed on potato dextrose agar (PDA) and incubated at 25℃ for 7 days in the dark. Six Clonostachys-like monospore isolates were obtained. Colonies on PDA reached 32 to 43 mm in diameter in 7 days at 25℃ in the dark, felty to tomentose to granulose aerial mycelia with a white or light yellow appearance, and reverse colors matching. On cornmeal-dextrose agar, primary conidiophores had a Verticillium-like structure with 1 to 3 levels. Stipes were 36.1 to 236.3µm long. Phialides formed in whorls of 2 to 5, 15.3 to 45.7µm long, 1.1 to 3.4µm wide at the base, and 1.03 to 2.41µm wide near opening (n=95). Each producing a small hyaline drop of conidia. Conidia were 3.7 to 11.3µm × 2.1 to 4.1µm (n=110). Secondary conidiophores displayed Penicillium-like structures, and stipes were 23.1 to 142.3µm long. Phialides formed in compressed whorls of 4 to 8 per metula, 7.0 to 16.0µm in length, 1.3 to 3.1µm in width at the base, 1.8 to 3.6µm at the widest point, and 0.8 to 1.8µm near opening (n=50). Conidia were 3.0 to 6.4µm ×1.6 to 3.4µm (n=65). The morphology was consistent with the previous description of Clonostachys rosea (Hans-Josef et al. 1999). The ATP citrate lyase (ACL1), ß-tubulin (TUB2), translation elongation factor 1-α (tef1α), and the nuclear ribosomal internal transcribed spacer (ITS) of three strains were amplified and sequenced using primers acl1-230up/acl1-1220low (Gräfenhan et al. 2011), T1/CYLTUB1R (Crous et al. 2004; O'Donnell and Cigelnik 1997), EF1-728F/EF2 (Carbone and Kohn 1999; O'Donnell et al. 1998), and ITS1/ITS4 (White et al. 1990), respectively. Blastn homology search showed a > 97% similarity to the ex-type strains of C. rosea (CBS710.86). All sequences have been deposited in GenBank (PP394342 to PP394350, and PP396901 to PP396903). A phylogenetic tree was constructed using Bayesian analysis based on the alignment of the combined ACL1, TUB2, tef1α, and ITS sequences through IQ-TREE. The tree displayed clustering with known strains of C. rosea. Pathogenicity was confirmed by inoculating five healthy five-year-old Taibai beimu plants with a spore suspension (1.0 × 106 spores mL-1) of the strain WYEB1101, while sterilized water was used as a control. The inoculation process involved pouring the spore suspension over the wounded bulbs and covering with them sterile soil. Subsequently, all plants were cultivated in sterile soil indoors under natural conditions suitable for Taibai beimu. The pathogenicity assays were repeated twice. After 20 days of cultivation, the infected plants displayed symptoms similar to those observed in the field, while all control plants remained asymptomatic. Sequencing confirmed the re-isolation of C. rosea from the inoculated plants, satisfying Koch's hypothesis. Clonostachys rosea has been previously reported to cause root rot of Chinese medicine herb, such as Astragalus membranaceus and Gastrodia elata (Lee et al. 2020; Qi et al. 2022). To our knowledge, this is the first report of C. rosea infecting Taibai Beimu in China, highlighting a potential risk to this crop.

First Report of Wilt Caused by Fusarium nanum (FIESC 25) on Mungbean (Vigna radiata) in Pakistan.

Mungbean, Vigna radia (L.) R. Wilczek, is ranked 2nd next to chickpea (Cicer arietinum) in total cultivation and production in Pakistan. In August of 2022 and 2023, mungbean plants (cv. PRI Mung-2018) were found wilting in a field at the Ayub Agricultural Research Institute, Faisalabad, Pakistan. Wilted leaves turned yellow, died, but remained attached to the stem. Vascular tissue at the base of the stem showed light to dark brown discoloration. Roots were stunted with purplish brown to black discoloration. Symptomatic mungbean plants were collected from fields at five different locations (20 samples/location). Disease incidence was similar among the five fields, ranging from 5 to 10% at each location depending upon type of germplasm and date of sowing. For fungal isolation and morphological identification, symptomatic stem and root tissues were cut into ~5 mm2 pieces with a sterilized blade. Tissues were surface-sterilized for one min in a 0.5% sodium hypochlorite solution, rinsed twice in sterilized water, air dried on sterilized filter paper, and aseptically placed on potato dextrose agar (PDA) containing 0.5 g/L-1 streptomycin sulphate. Plates were incubated for 3-4 days at 25 ± 2°C with a 12-h photoperiod. Single-spore cultures were used for morphological and molecular analyses. Isolates on PDA grew rapidly and produced abundant white aerial mycelium that turned off-white to beige with age. Macroconidia were hyaline, falcate, typically 3-to-6 septate with a pointed apical cell and a foot-shaped basal cell, measuring 24.5-49.5 x 2.7-4.7 µm (n = 40). Globose to obovate chlamydospores measuring 5.8 ± 0.5 µm (n = 40) were produced singly or in chains and were intercalary or terminal and possessed roughened walls. The morphological data indicated the isolates were members of the genus Fusarium (Leslie and Summerell 2006). To obtain a species-level identification, a portion of translation elongation factor 1-α (TEF1), the largest subunit of RNA polymerase (RPB1), and the second largest subunit of RNA polymerase (RPB2) region were PCR amplified and sequenced using EF1/EF2 (O'Donnell et al. 1998), Fa/G2R (Hofstetter et al. 2007), and 5f2/7cr (Liu et al. 1999) primers, respectively. DNA sequences of these genes were deposited in GenBank under accession numbers MW059021, MW059017 and MW059019, respectively. The partial TEF1, RPB1 and RPB2 sequences were queried against the Fusarium MLST database (https://fusarium.mycobank.org/page/Fusarium_identification), using the polyphasic identification tool. The BLASTn search revealed 99.9% identity of the isolate to F. nanum (Xia et al. 2019), formerly FIESC 25 of the F. incarnatum-equiseti species complex (MRC 2610, NRRL 54143; O'Donnell et al. 2018). To confirm pathogenicity, roots of 3-5 leaf stage mungbean seedlings were soaked in a 106 spores ml-1 conidial suspension of the fungus for 15 min and then planted in 10 cm pots containing sterilized soil. Mock-inoculated plants with sterile water served as a negative control. Twenty pots that were used for each inoculated and control treatment were maintained at 25 ± 2°C, 14:8 h photoperiod, and 80% relative humidity in a growth chamber. After 15 days, leaf yellowing, internal browning from the base of stems and root discoloration was observed in all the inoculated plants. The uninoculated negative control plants remained asymptomatic. Fusarium nanum was re-isolated from artificially inoculated plants and identified by colony growth, conidial characteristics on PDA and molecular analyses (TEF1). To our knowledge, this is the first report of wilt caused by F.nanum on mungbean in Pakistan. In Pakistan, mungbean cultivation in irrigated areas has increased in recent years. It has been introduced frequently in citrus orchards, crop rotation of maize and sesame, intercropping with sugarcane and as green manure. However, citrus, maize, sesame and sugarcane are also hosts of Fusarium spp. Therefore, this information warrants sustainable crop protection and may have an impact on further interaction of F. nanum with other wilt pathogens.

Discovery of Fusarium pseudograminearum Causing Crown Rot of Winter Wheat in Xinjiang Uygur Autonomous Region, China.

Fusarium pseudograminearum is an important plant pathogen that invades many crops (Zhang et al. 2018). Since it was first discovered in Australia in 1951, F. pseudograminearum has been reported in many countries and regions and caused huge economic losses (Burgess et al. 2001). In 2012, crown rot of wheat caused by F. pseudograminearum was discovered for the first time in Henan Province, China (Li et al. 2012). Wheat (Triticum aestivum L.) is one of the most important food crops in Xinjiang Uygur Autonomous Region (XUAR), with 1.07 million hectares cultivated in 2020. In June 2023, a survey of crown rot disease was carried out in winter wheat cv. Xindong 20 in Hotan area, XUAR, China (80.148907°E, 37.051474°N). About 5% of wheat plants showed symptoms of crown rot such as browning of the stem base and white head. The disease was observed in 85% of wheat fields. In order to identify the pathogens, 36 pieces of diseased stem basal tissue, 0.5 cm in length, were collected and sterilized with 75% alcohol for 30s and 5% NaOCl solution for 2 min, then rinsed three times with sterile water and placed on potato dextrose agar (PDA) medium at 25°C. A total of 27 isolates with consistent morphological characteristics were obtained using single-spore technique (Leslie and Summerell. 2006), and the isolation rate was 75%. The isolates grew rapidly on PDA, produced large numbers of fluffy white hyphae, and pink pigment accumulated in the medium. The isolates were grown on 2% mung bean flour medium and identified by morphological and molecular methods. Macroconidia were abundant, relatively slender, curved to almost straight, commonly two to seven septate, and averaged 22 to 72 × 1.8 to 4.9 µm. Microconidia were not observed. The morphological characters are consistent with Fusarium (Aoki and O'Donnell. 1999). Two isolates (LP-1 and LP-3) were selected for molecular identification. Primers EF1/EF2 (5'-ATGGGTAAGGARGACAAGAC-3'/5'-GGARGTACCAGTSATCATG-3') were used to amplify a portion of the EF-1α gene (O'Donnell et al. 1998). The two 696 bp PCR products were sequenced and submitted to GenBank. The EF-1α gene sequences (GenBank Accession No: PP062794 and PP062795) shared 99.9% identity (695/696) with published F.pseudograminearum sequences (e.g., OP105187, OP105184, OP105179, OP105173). The identification was further confirmed by F. pseudograminearum species-specific PCR primers Fp1-1/Fp1-2 (Aoki and O'Donnell. 1999). The expected PCR products of 518 bp were produced only in F. pseudograminearum. Pathogenicity tests of LP-1 and LP-3 isolates were performed on 7-day-old seedlings of winter wheat cv. Xindong 20 using the drip inoculation method with a 10-µl of a 106 macroconidia ml-1 suspension near the stem base (Xu et al. 2017). The experiment was repeated five times in a 20 to 25°C greenhouse. Control seedlings were treated with sterile water. After 4 weeks, wheat seedling death and crown browning occurred in the inoculated plants with over 90% incidence. No symptoms were observed in the control plants. The pathogen was reisolated from the inoculated plants by the method described above and identified by morphological and PCR amplification using F. pseudograminearum species-specific primers Fp1-1/Fp1-2. No F. pseudograminearum was isolated from the control plants, fulfilling Koch's postulates. To our knowledge, this is the first report of F. pseudograminearum causing crown rot of winter wheat in XUAR of China. Since F. pseudograminearum can cause great damage to wheat, one of the most important food crops in China, necessary measures should be taken to prevent the spread of F. pseudograminearum to other regions.

Host Range Characterization of Phytophthora sansomeana Across Corn, Soybean, Wheat, Winter Cereal Rye, Dry Bean, and Oats and an In Vitro Assessment of Seed Treatment Sensitivity.

Formally described in 2009, Phytophthora sansomeana is a pathogen of increasing interest in native, agricultural, and horticulturally important plant species. The objective of this study was to elucidate the symptomatic and asymptomatic host range of P. sansomeana on six agricultural crop species commonly used in field crop rotations in Michigan. In addition, sensitivity to oomicides commonly used in seed treatments, including oxathiapiprolin, mefenoxam, ethaboxam, and pyraclostrobin, was performed to aid in disease management recommendations. Plant biomass, quantity of P. sansomeana DNA in roots, and reisolations were used to assess pathogenicity and virulence of 18 isolates of P. sansomeana on each plant species using an inoculated seedling growth chamber assay. Isolates displayed varying levels of virulence to the hosts tested. Reisolations were completed for each plant species tested, and varying quantities of P. sansomeana DNA were found within all plant species root samples. Corn, wheat, soybean, dry bean, and winter cereal rye plants were symptomatic hosts with significant reduction observed in the total plant biomass. No significant reduction in total plant biomass was observed in oats, and oat roots harbored the least amount of P. sansomeana DNA. No P. sansomeana isolates were insensitive to the oomicide compounds tested with mean absolute inhibition (EC50) values of fungicide required for 50% growth inhibition values of 7.8 × 10-2 µg/ml for mefenoxam, 1.13 × 10-1 µg/ml for ethaboxam, 2.6 × 10-2 µg/ml for oxathiapiprolin, and 3.04 × 10-1 µg/ml for pyraclostrobin. These results suggest that common crop rotations in Michigan may not be a viable option to reduce soilborne inoculum accumulation and oomicide seed treatments could be considered for early-season management of P. sansomeana.