Journal of Phytopathology最新文献

Celery (Apium graveolens L.) displaying wilting and soft rot were collected from open field and hydroponic systems. Greater than 80% crop loss was reported by affected farmers in both the hydroponic and open field cultivation. Isolation on nutrient agar revealed colonies which are morphologically identical. Whole genome sequence analysis and multilocus sequence analysis indicate the strains CSR2 and CSR3 to be very closely related to Pectobacterium colocasium LJ1 GCF 020181655.1 (NZ_CP084032.1). However, the average nucleotide identity of the strains to Pectobacterium colocasium is less than 95%, which is below the accepted threshold for species delineation. Host range studies revealed that in addition to celery, the bacterium is capable of infecting a broader spectrum of crops, including cabbage, cauliflower, carrot, pak choi, cucumber and pumpkin. The findings highlight the potential threat of the bacterium to food security with the potential to impact multiple economically important crops in Trinidad. This study identifies a new species of Pectobacterium causing soft rot in celery with the possibility of impacting several other crops of economic importance.

African iris (Dietes bicolor) is a rhizomatous ornamental plant widely used in landscape design. In 2025, plants showing chlorosis, reduced development, and root galls typical of Meloidogyne spp. were observed in a nursery in Santa Maria, Rio Grande do Sul, Brazil. Eggs and second-stage juveniles (J2) were extracted from symptomatic roots, with an average density of 327 eggs and J2 per gram of root. Adult females collected from infected roots were used for isoenzymatic characterisation. Individual females were macerated in sucrose–Triton X-100 buffer and analysed by polyacrylamide gel electrophoresis. The resulting esterase profile exhibited the characteristic J3 phenotype, identifying the population as Meloidogyne javanica. For molecular confirmation, DNA was extracted from single females, and PCR amplification using the species-specific primers Fjav/Rjav consistently amplified the expected ~670 bp SCAR fragment. Pathogenicity was verified by inoculating healthy D. bicolor plants with 2,500 eggs. After 60 days, the reproduction factor was 2.1, and symptoms matched those observed in naturally infected plants, fulfilling Koch's postulates. This is the first report of M. javanica parasitizing D. bicolor in Brazil and, for the best of our knowledge, the first global record of this host–nematode association.

Fungal diseases significantly reduce the postharvest quality and marketability of durian (Durio zibethinus), especially in regions with humid tropical climates such as the Mekong Delta, Viet Nam. This study aimed to isolate and identify pathogenic fungi associated with diseased durian fruits and leaves, and to evaluate the antifungal potential of leaf extracts from five Rubiaceae species (Ixora duffii, Neonauclea orientalis, Neolamarckia cadamba, Paederia lanuginosa, and Paederia scandens). Nine fungal isolates were first obtained, among which three representative isolates were identified through morphological and molecular analyses as Lasiodiplodia theobromae, Diaporthe lithocarpus, and Lasiodiplodia pseudotheobromae. Pathogenicity tests confirmed their ability to induce fruit rot or leaf lesions. Antifungal assays revealed that all Rubiaceae extracts inhibited mycelial growth in a concentration-dependent manner. Notably, Ixora duffii and Neonauclea orientalis demonstrated the highest activity, achieving complete suppression of Lasiodiplodia theobromae at 6.4 mg/mL, comparable to commercial fungicide control. These results indicate that Rubiaceae species, especially Ixora duffii, may serve as useful sources of antifungal compounds for improving the sustainable management of postharvest diseases in durian.

Late blight, caused by Phytophthora infestans, is the most serious threat to sustainable potato production in Ethiopia, causing major yield losses and forcing the farmers to rely heavily on fungicides, which increase production costs and contribute to environmental pollution. Potato growers usually apply fungicides without a reliable potato late blight management decision support system. There is a gap in the development of weather-based potato late blight forecasting models suitable for Ethiopia's diverse agro-ecological conditions. This study was carried out during the 2022, 2023 and 2024 main cropping seasons at three major potato-producing areas: Haramaya, Holeta and Negele Arsi to identify key weather variables significantly influencing potato late blight onset and progression, and develop location-specific weather-based forecasting models. The number of rainy days and mean minimum temperature recorded 5 and 7 days before disease assessment dates were highly significant (p < 0.001). Variables showing strong Pearson correlation with absolute rate of disease severity change (r = 0.75–0.93) were selected for modelling. General Linear Mixed Models (GLMM) revealed that each additional rainy day increased disease severity by 0.12, 0.14 and 0.07 at Haramaya, Holeta and Negele Arsi, respectively, on the susceptible variety Jalene, and by 0.09, 0.10 and 0.07 on the moderately resistant variety Gudene, assuming constant temperature. Optimal management intervention times were identified as 36–38, 45–47 and 48–50 days after planting (DAP) at Holeta, Haramaya, and Negele Arsi, respectively, ahead of disease onset at 43, 50 and 55 DAP, respectively. Overall, the results show that adopting these area-specific, weather-based forecasting models can help farmers improve the timing of late blight management and reduce unnecessary fungicide use.

Gastrodia elata, a traditional medicinal plant used for over 2000 years, is highly susceptible to fungal diseases, and tuber rot has recently caused severe yield losses in Hongjiang, Hunan Province, China. Diseased tubers exhibited black surface lesions, with the underlying tissues softened into a pulpy mass, accompanied by mucilage that adheres to soil particles and a strong foul odour. The causal pathogen was isolated in pure culture and identified as Fuscohypha expansa based on detailed morphological characteristics and multilocus phylogenetic analyses of ITS, LSU and RPB2 sequences. Pathogenicity tests fulfilling Koch's postulates confirmed its ability to reproduce typical symptoms on G. elata tubers. To our knowledge, this study provides the first report of the genus Fuscohypha in China and its first evidence as a plant pathogen, offering new insights into disease aetiology and a foundation for future management strategies.

Avocado (Persea americana Mill.) is a high-value fruit crop with growing demand in Vietnam. However, its postharvest life is severely constrained by microbial decay, and knowledge of causal pathogens in Vietnam remains limited. This study aims to identify microorganisms associated with postharvest spoilage of avocado cv. 034 and to evaluate their effects on fruit quality during storage under experimental conditions. Pathogens were isolated and characterised based on morphological and molecular features, and Koch's postulates were applied to confirm pathogenicity. Three microorganisms were identified as associated with avocado decay, including Enterobacter cloacae, Pectobacterium carotovorum and Lasiodiplodia theobromae. Inoculation assays showed that these pathogens significantly accelerated fruit softening, decreased pH, increased titratable acidity and total soluble solids and enhanced oxidative enzyme activities (polyphenol oxidase and peroxidase). These physiological alterations led to peeling lesions, pulp browning and tissue maceration, resulting in a severe decline in storage quality. Overall, this study provides an initial characterisation of microorganisms associated with postharvest decay of avocado cv. 034 under experimental conditions. It also highlights the need for broader surveys and genome-based analyses to clarify their epidemiological roles in commercial production systems, thereby informing future research on sustainable management strategies to mitigate postharvest losses and preserve avocado fruit quality during storage.

A field experiment was conducted during the 2019 main cropping season at Aneded and Banja districts in northwestern Ethiopia to evaluate the effects of host resistance and fungicide application timing on stripe rust caused by (Puccinia striiformis f. sp. tritici) and grain yield of bread wheat (Triticum aestivum L.). The experiment comprised three wheat varieties and five fungicide (epoxiconazole + thiophanate-methyl) application timings—(7, 14, 21 and 28 days after symptom occurrence) and an untreated control, arranged in a factorial randomised complete block design with three replications. Significant (p ≤ 0.01) differences were observed among treatments for both disease and yield parameters. The greatest disease reduction and yield improvement were achieved when the resistant variety Wane was combined with fungicide application at 7 days after symptom occurrence. The findings demonstrate that integrating resistant wheat varieties with timely fungicide application effectively manages stripe rust and minimises yield losses. A cost–benefit analysis further revealed that the combination of resistant or moderately resistant varieties with a fungicide applied 7 days after symptom appearance provided the highest net benefit. Therefore, the use of resistant varieties in combination with appropriately timed fungicide application is recommended to achieve sustainable stripe rust management and maintain high wheat productivity in northwestern Ethiopia.

Walnut anthracnose, primarily caused by Colletotrichum gloeosporioides, poses a significant threat to walnut production. This study presents a novel and sustainable strategy for managing walnut anthracnose by reusing fermented vegetable residues (jiaosu). Repeated, preventative soil applications of four types of jiaosu derived from wax gourd, pumpkin, Chinese cabbage and cabbage were evaluated for their efficacy against anthracnose and impact on soil health in a pot trial. Pumpkin jiaosu exhibited the strongest disease-suppressive effect, significantly reducing disease severity at 15 days post-inoculation. The mean leaf lesion in treated walnut seedlings (0.67 cm) was only 28.38% of the control plants (2.36 cm). Soil application of jiaosu enhanced chlorophyll and soluble protein content, increased polyphenol oxidase activity and mitigated cell membrane damage and reactive oxygen species accumulation in walnut seedlings. Jiasou application also significantly improved soil properties, including organic matter, available nitrogen, available phosphorus, alkaline phosphatase and urease. Organic matter content increased from 8.84 to 10.95 g/kg following treatment with Chinese cabbage jiaosu. Microbial community analysis revealed that pumpkin jiaosu enhanced soil microbial diversity and that the decline in Acidobacteria abundance under pathogen stress was alleviated. Field trials further demonstrated a significant increase in Firmicutes abundance at 60 days after pumpkin jiaosu application. These findings indicate that reusing fermented vegetable residues—particularly pumpkin jiaosu—offers an eco-friendly and effective approach for controlling walnut anthracnose and enhancing soil health.

Tylenchulus semipenetrans (Cobb 1913) is an important plant-parasitic nematode that severely affects citrus nurseries and orchard productivity worldwide. It infects feeder roots of young citrus plants, leading to ‘slow decline’ symptoms such as stunted growth, leaf yellowing and weakened root systems. These early symptoms highlight the need for timely detection and intervention. Nursery plants serve as primary inoculum sources for field infestations, emphasising the importance of quarantine and effective sanitation. This review explores the nematode's biology, morphology, host interactions, advanced techniques for early detection and the unique challenges it poses in nursery environments. Emphasis is placed on recent advancements in detection methods and integrated management strategies. These include the use of bio-intensive approaches, deployment of resistant rootstocks, and manipulation of the rhizosphere microbiome to suppress nematode populations. The paper also highlights the importance of sustainable, holistic solutions that combine traditional and innovative practices. By integrating the most recent scientific findings and management approaches, this review aims to support the development of nematode-free nursery systems, ultimately promoting resilient and sustainable citrus production across affected regions.