Journal of Phytopathology最新文献

Colletotrichum siamense is an emerging plant pathogen with a broad host range and increasing global prevalence, yet its role in ornamental plant diseases remains underexplored. This study reports the first detailed characterisation of C. siamense associated with anthracnose symptoms on Ficus elastica. The fungus was isolated from symptomatic leaves exhibiting dark, necrotic lesions with yellow halos. Morphophysiological features were consistent with C. siamense and included fast-growing floccose colonies, globose conidiomata, cylindrical conidia, and melanized appressoria. Species identity was confirmed through multilocus sequencing of ITS and β-tubulin (BenA) regions, and phylogenetic analyses clustered the isolate with known C. siamense strains from diverse hosts. Additionally, physiological assays revealed enzymatic activity for amylase, hemicellulases, and laccases, whereas the activity of cellulases was absent. Finally, pathogenicity trials on healthy F. elastica leaves fulfilled Koch's postulates, with symptomatic lesions and successful re-isolation of the pathogen. An NCBI database search retrieved over 38,000 C. siamense sequences, with only two associated with F. elastica, underscoring the rarity of reported infections in this host. This study not only expands the known host range of C. siamense but also highlights its pathogenic potential in indoor ornamental settings. These findings emphasise the importance of accurate pathogen identification using a polyphasic approach and underscore the need for phytosanitary vigilance to manage emerging threats to ornamental horticulture.

Rhododendron latoucheae is a globally renowned ornamental plant valued for its aesthetic appeal and economic significance. In May 2023, a leaf blight disease was observed on R. latoucheae in Guizhou Province, China, with approximately 20% of 500 surveyed plants showing symptoms of irregular reddish-brown lesions bearing black conidial clusters. The causal agent was identified as Neopestalotiopsis cubana through morphological characterisation and multilocus phylogenetic analysis (ITS, tef1-α, tub2). Pathogenicity was confirmed in accordance with Koch's postulates. To our knowledge, this is the first report of N. cubana causing leaf blight on R. latoucheae. In vitro screening of nine fungicides revealed high efficacy of mancozeb, azoxystrobin, tebuconazole, oxime·tebuconazole, and osthole, with EC₅₀ values below 10 μg·mL⁻¹. These results provide key insights for diagnostic and chemical management strategies against this emerging disease.

Hot pepper is a vital crop in Ethiopia and worldwide, valued for its pungency and as a source of income for stallholder farmers. However, production is severely impacted by Fusarium wilt, leading to yield losses ranging from 10% to 80% and significant economic damage, estimated at $65.3 billion globally. In Ethiopia, Fusarium wilt is widespread, with an incidence rate of 86.6% and yield losses reaching up to 80%. The pathogen blooms in warm, humid conditions, with optimal growth at 25°C and pH 7.0. It infects plants through roots, colonising the xylem and leading to wilting and plant death. The disease spreads through contaminated soil, water, farming tools, and infected seeds, making it difficult to control. Timely and precise diagnosis using morphological features (such as colony colour, shape, and spore structure) and molecular techniques (like PCR targeting and sequencing EF-1α and rpb2 genes, and additional genetic markers acl1, tub2, CaM, and rpb1) are essential to design effective management options. The pathogen's virulence is driven by toxin production, cell wall-degrading enzymes, and effector proteins that suppress plant immunity. Management includes cultural practices, biocontrol, and fungicides, though resistance is a concern. Integrated disease management (IDM), combining these approaches, offers sustainable control of Fusarium wilt. Modern biotechnological tools such as gene editing (CRISPR-Cas9) and RNA interference (RNAi) offer promising solutions but remain underutilised. Although there are identified resistant genotypes, adoption remains limited. This review emphasises the importance of integrated management and multi-omics approaches to improve resistance breeding, along with advocating for farmer education and policy support to reduce crop losses.

Bai-ji (Bletilla striata), an economically important medicinal herb cultivated in Yunnan Province, China, was observed with severe anthracnose symptoms in July 2021. Through comprehensive morphological characterisation and multilocus phylogenetic analysis (ITS, ACT, TUB, and GAPDH gene regions), the causal agent was identified as Colletotrichum cymbidiicola. Initial symptoms manifested as brown necrotic lesions that progressively developed into elliptical or fusiform spots with light brown centers. Koch's postulates confirmed that C. cymbidiicola was the etiological agent. This study is the first documented case of C. cymbidiicola infecting B. striata in China, providing valuable phytopathological insights for the sustainable cultivation of this medicinal species.

This study reports Neofusicoccum parvum for the first time in grapevine planting material in Montenegro, alongside the first detection of the endophytic fungus Trichoderma citrinoviride in the country. Recognising the critical role of healthy planting material in managing Grapevine Trunk Diseases (GTDs), asymptomatic grafted vines from a domestic nursery and imported sources were analysed. Fungal isolates were recovered from woody tissues and identified based on morphological characteristics and molecular sequencing of the ITS, TEF1-α, TUB2, LSU and RPB2 genes. Neofusicoccum parvum was the sole GTD-associated pathogen detected, confirming that planting material, particularly imports, represents a major pathway for disease introduction. Considering the analysis of planting material from multiple countries included in this study, these findings have significant phytosanitary implications for both Montenegrin viticulture and viticulture of the Balkan. Trichoderma citrinoviride, isolated from Vitis vinifera cv. Vranac in Montenegro, was evaluated both in vitro and in planta for antagonistic activity against N. parvum, showing promising inhibitory effects. These results highlight the urgent need for strict nursery sanitation and phytosanitary monitoring and provide a basis for further evaluation of T. citrinoviride as a potential biocontrol agent in sustainable GTD management.

Rice brown spot (RBS), mainly caused by Bipolaris oryzae, is an emerging threat to rice production across Africa, particularly within lowland rice ecosystems that dominate the region. Despite its growing impact, knowledge of the environmental factors influencing RBS occurrence remains limited. This study aimed to elucidate the influence of meteorological variables on RBS prevalence in Côte d'Ivoire, spanning three major agro-ecological zones. Field surveys were conducted in 99 farmer-managed fields during both the rainy and dry seasons from 2021 to 2022, and average RBS severity was calculated across different stands within each field. Parameters assessed included air temperature, relative humidity, wind speed, soil moisture, solar radiation, and rainfall. Linear regression analyses were used to identify main drivers, and regression models were developed to project future risk maps under SSP2-4.5 (moderate) and SSP5-8.5 (high) climate scenarios. Key drivers were identified: air temperatures above 27°C and wind speeds exceeding 1 m/s were associated with decreased disease prevalence, whereas relative humidity above 80%, wet bulb and dew point temperatures between 23°C and 27°C, and soil moisture and wetness in the range of 0.4–0.7 significantly promoted RBS development. Results revealed a yearly increase in RBS severity, ranging from 2.47 to 3.46 (on a 0–5 scale), with consistently higher prevalence during the rainy seasons. Predictive modelling based on these variables suggests a likely expansion and intensification of RBS risk for the future. Under a high-emission scenario, RBS severity could reach 4.9 by the late 21st century, while the moderate scenario projects a peak severity of 4.33 between 2060 and 2080. These findings underscore the pivotal role of climate in shaping RBS risk and highlight the urgent need for climate-adaptive disease management strategies to sustain rice production in Africa.