Plant disease最新文献

Fusarium wilt of watermelon (Citrullus lanatus), caused by Fusarium oxysporum f. sp. niveum, severely threatens watermelon production worldwide. This study, for the first time, explored a rapid and efficient method for creating disease-resistant watermelon germplasm by combining ethyl methanesulfonate (EMS) mutagenesis with crude toxin screening. Watermelon seeds treated with 1% EMS for 18 h achieved a germination rate of 52%, and resistant mutants were successfully identified using 50% crude toxin stock solution. The mutants exhibited enhanced stress tolerance, with significantly higher superoxide dismutase and catalase activities and lower malondialdehyde content compared with susceptible varieties. Artificial fungal inoculation confirmed the resistance of mutant plants, which exhibited a disease index comparable with that of the resistant varieties. This study demonstrated the effectiveness of a practical and innovative strategy combining chemical mutagenesis and toxin screening for developing Fusarium wilt-resistant watermelon germplasm.

Apple Marssonina blotch (AMB), caused by Marssonina coronaria, endangers apple production on China's Loess Plateau. Climate change has increased its outbreaks, but future distributional impacts remain unclear. Using 832 field records and an eight-model BIOMOD2 (a species distribution modeling platform) ensemble (True Skill Statistic, TSS = 0.90; Area Under the Receiver Operating Characteristic Curve, AUC = 0.98), we projected AMB suitability under Shared Socioeconomic Pathways (SSP) 1_2.6 (low greenhouse gas emission scenario), SSP3_7.0 (medium greenhouse gas emission scenario) and SSP5_8.5 (high greenhouse gas emission scenario) for 2041-2070. Schoener's D (an ecological niche overlap index, 0 = no overlap, 1 = complete overlap) < 0.45 indicates a niche shift toward regions with intensified precipitation seasonality and elevated warm-season precipitation. Key climatic constraints shaping AMB's distribution included the mean diurnal temperature range (39.7%), precipitation seasonality (21.4%), isothermality (15.6%), warm-season precipitation (12.8%), and annual mean temperature (10.5%). Currently, high-suitability habitats for AMB span 2.36 × 10⁴ km² in western Guanzhong. By 2070, the high-suitability areas of this pathogen are projected to decline by 67%, 78% and 86% under SSP1_2.6, SSP3_7.0 and SSP5_8.5, respectively, and will retreat to fragmented, high-elevation refugia in the northern Loess Plateau. Only the SSP5_8.5 achieves a 12% net gain in total suitable area, predominantly from low-suitability zones. Schoener's D (a metric quantifying ecological niche overlap, ranging from 0 = no overlap to 1 = complete overlap) < 0.45 indicates a niche shift toward regions with intensified precipitation seasonality and elevated warm-season precipitation, with the range centroid shifting northeast by up to 109 km. Future warming may favor northern habitats, but spring drought and summer heat stress will restrict colonization, creating a "warming-drying trade-off." Overall, climate change will compress AMB's optimal habitat into isolated, high-altitude patches, reducing disease stability in traditional apple-growing regions. These projections provide scientific support for developing early warning systems and climate-adaptive management strategies for AMB.

Over the past century, citrus tristeza virus (CTV) has inflicted serious losses to the global citrus industry, primarily through the two most destructive diseases in citrus hosts: decline (tristeza) and stem pitting. Because of its widespread distribution, CTV has attracted significant attention from researchers worldwide. As the result of collective efforts, the industry has managed to mitigate the impact of CTV and avoid catastrophic outcomes. However, the virus remains a continually evolving threat, with new variants emerging and spreading into new areas. In light of the history of severe CTV outbreaks and an ongoing risk the virus poses to global citriculture, we assembled a team of leading CTV experts from major citrus-producing regions to prepare this Feature Article. The article provides an overview of the current global status of CTV, discussing its spread and impact, and outlines the management strategies employed around the world to protect citrus production and ensure its long-term sustainability.

Sugarcane leaf scald, caused by Xanthomonas albilineans, is a destructive bacterial disease that threatens sugarcane production. Successful disease development depends on the pathogen's ability to move, colonize host tissues, and spread within plants, yet the regulatory mechanisms underlying these processes remain poorly understood. In this study, we investigated the role of the histidine kinase RavS in the pathogenicity of X. albilineans. A ravS deletion mutant (ΔravS) exhibited significantly reduced swimming and swarming motility, impaired growth, and markedly decreased virulence on sugarcane compared with the wild-type strain. Genetic complementation restored all phenotypes to wild-type levels. Comparative transcriptome analysis revealed that deletion of ravS resulted in coordinated repression of genes involved in flagellar assembly and chemotaxis, processes that are essential for bacterial movement and host colonization. In contrast, tolerances to oxidative stress (H₂O₂), ionic stress (CaCl₂ and MgSO₄), and pH stress were unaffected. Together, these results demonstrate that RavS promotes the development of sugarcane leaf scald by regulating motility-associated pathways that enable X. albilineans to colonize and cause disease in sugarcane effectively.

Northern (Exserohilum turcicum) and southern (Bipolaris maydis) corn leaf blights threaten fresh-market sweet corn in Florida, yet region-specific data on efficacy and economics of fungicide programs are scarce. Four replicated field trials were conducted in Belle Glade, FL (spring 2023, spring 2024, fall 2024, spring 2025) comparing eight treatments with foliar programs that contrasted early pre-tassel (V3/V7 growth stages; mancozeb mixed with single-site fungicides) with systemic-only programs beginning at tasseling/silking (VT/R1). Yield was collected in 2023 and 2025. Under high disease pressure (disease severity > 80%), early fungicide programs reduced relative area under disease progress curve (rAUDPC) more than VT and R1 programs. Results were consistent across independent epidemics: in southern corn leaf blight epidemics, programs initiated at V3 and V7 limited mean rAUDPC to 19% versus 47% in non-treated; in northern corn leaf blight epidemic, V3/V7 programs averaged 6% versus 36% in non-treated. Yield responses paralleled disease control. The best programs protected yield by 2.44 t ha⁻¹ in 2023 (two pass V7 and R1) and by 1.93 t ha⁻¹ in 2025 (four pass grower standard). Treated plots showed greater kernel filling, which mediated most of yield response. Economic results were favorable, with typical program costs covered by ≤0.4 t ha⁻¹ of protected yield, and top programs demonstrated ROI of 92 to 762%. In subtropical sweet corn, starting protection by V7 and maintaining coverage through VT/R1 maximizes blight suppression, safeguards kernel fill, and improves profitability. Streamlined two-pass programs can match three- or four-pass schedules while reducing inputs and stewardship risks.

Wheat stem rust, caused by Puccinia graminis f. sp. tritici (Pgt), is a persistent threat to Ethiopian wheat production, posing risks to food security. This study evaluated the virulence and genotypic diversity of the Pgt population following the stem rust epidemic in 2013, and the vulnerability of Ethiopian bread wheat cultivars to the newly identified Pgt races. We analyzed 639 stem rust samples collected between 2014 and 2022 in Ethiopia and identified 21 Pgt races from 722 single-pustule isolates. The Ethiopian Pgt population has undergone significant temporal shifts driven by exotic race introductions and possibly by selection pressure. Race TKTTF (clades IV-A and -B) dominated in 2014-2016 seasons but was largely replaced by races TTRTF (clade III-B) and TKKTF (clade IV-F) from 2017 onward. Since 2020, races TTKTT (clade I) and TTKTF (clade IV-F) were detected with increasing frequencies, emerging alongside TKKTF as the predominant races by 2022. All major races from genetic clades III and IV detected in Ethiopia exhibit a similar, broad geographic distribution with a likely origin in the Caucasus region. All five variants in the Ug99 race group (clade I) observed in Ethiopia were previously detected in Kenya, suggesting a potential incursion from this bordering country. Races BKBJC and BKGKC with distinct avirulence and genotypic profiles were derived from a sample collected near the alternate host Berberis holstii, suggesting that these avirulent isolates likely originated through sexual recombination. Seedling assays of 101 Ethiopian bread wheat cultivars against six prevailing races showed varying resistance, with only 36% and 48% resistant to race TTKTT and TTKSK, respectively. Although resistance genes deployed in Ethiopian cultivars do not appear to have exerted significant selection pressure favoring races TTRTF and TKKTF, the increased deployment of Sr24 in recent years may have contributed to the establishment and dissemination of race TTKTT. Our findings emphasize the need for breeding wheat cultivars with pyramided effective resistance genes and continuous pathogen surveillance to preempt future stem rust epidemics in Ethiopia and beyond.

Sclerotinia stem rot (SSR), caused by fungal pathogen Sclerotinia sclerotiorum, is one of the leading contributors to yield losses in soybean. The fungus forms sclerotia that persist through the off-season and germinate under favorable conditions to infect soybean. Among the practices used to manage SSR, biological control with Coniothyrium minitans is an effective strategy to suppress S. sclerotiorum through direct interaction. However, both S. sclerotiorum and C. minitans, can interact with soil amendments, including fertilizers, with implications for SSR management. Since potassium is widely applied in soybean production in Wisconsin, this study aimed to investigate the effect of KCl on S. sclerotiorum, C. minitans, and their interaction in vitro. While radial growth of S. sclerotiorum was unaffected by KCl concentration, linear models effectively described decrease in number of sclerotia produced and the increase in sclerotial diameter and weight with increasing KCl concentration. Oxalic acid production declined with increase in KCl concentration, which was best captured by a non-linear exponential model, while sclerotial germination time decreased according to a linear model. Radial growth of C. minitans exhibited a linear decline with increasing KCl concentration, whereas conidial germination remained unaffected. A non-linear logistic model revealed a positive effect of increasing KCl concentration on mycoparasitism of C. minitans on sclerotia of S. sclerotiorum. These findings provide insights into interactions of KCl with S. sclerotiorum and C. minitans that could inform the integration of potassium fertilization with biological control strategies for SSR management in the field.

Grape ripe rot, a globally significant fungal disease caused by Colletotrichum spp., severely threatens grape yield and quality. This study systematically investigated the pathogen species, biological characteristics, and fungicide sensitivity through multiregional sampling (2022 to 2024, covering seven districts across four provinces), morphological analysis, molecular identification, and EC₅₀ assays. The results revealed that 125 isolates were obtained and classified into five species, namely, Colletotrichum aenigma, C. conoides, C. viniferum, C. gloeosporioides, and C. fructicola, based on morphological traits and multilocus phylogenetic analysis (ITS, CHS, GAPDH, TUB2, and ACT). Among these, C. viniferum was identified as the dominant species responsible for grape ripe rot, with an isolation rate of 74.4%, and C. conoides represents a new species isolated from grape ripe rot in China. Biological assays revealed that the optimal temperature and pH for mycelial growth on PDA were 25 to 30°C and pH 5 to 6, respectively, and the pathogenicity significantly increased at 30°C following wound inoculation. Fungicide sensitivity tests indicated that prochloraz exhibited the highest inhibitory efficacy against all the species (EC₅₀ ≤ 0.03 mg/liter). This study elucidates the geographical distribution patterns of Colletotrichum spp. in China and their differential responses to fungicides, providing critical theoretical and practical insights for optimizing integrated management strategies against grape ripe rot.

Tea, Camellia sinensis, is a globally important crop plant that is currently under investigation for production in the Southeastern United States. Both in the United States and in traditional tea production regions, one of the most damaging diseases of tea is anthracnose, or brown blight, caused by various species of Colletotrichum. In the United States, only a single species had previously been reported on tea, whereas at least 12 species are known to cause disease in other regions, raising the question: Is the absence of additional species in U.S.-grown tea caused by differences between U.S. and Asian pathogen populations, or simply due to the limited acreage and duration of tea production in North America? We conducted a survey of Colletotrichum spp. in tea, in targeted plants likely to share pathogens with tea (ornamental camellias and blueberry), and in weeds around all three target hosts and conducted subsequent pathogenicity tests with representative isolates on tea. We identified 22 new host-fungus combinations for Colletotrichum species in the United States, 21 of which are also first reports globally. Further, we confirmed a second species of Colletotrichum causing anthracnose on tea in the United States, isolated Colletotrichum camelliae from multiple unrelated hosts, and demonstrated that isolates of both species recovered from other hosts are capable of causing disease on tea.

Silver scurf, caused by the fungus Helminthosporium solani, has become a growing potato disease concern in the United States. Conventional cultural management practices are often impractical or insufficient at a commercial scale, underscoring the need for effective fungicide treatments in integrated management approaches. H. solani initially infects tubers in the field, and secondary infection cycles could occur during storage. Inoculum could possibly be reduced at multiple stages during production. This study, conducted from 2015 to 2018, evaluated the effects of various fungicide treatments on silver scurf severity, potato emergence rate, and marketable yield. Fungicides were applied at three stages: (i) at planting, either as seed treatment or an in-furrow application; (ii) during field production as foliar treatment; and (iii) postharvest, prior to storage. We found seed treatment, either alone or in combination with foliar application, significantly reduced silver scurf severity at harvest in 3 of the 4 years of study. Additionally, seed treatment alone significantly reduced tuber disease severity after 90 days of storage in 2 of the 4 years. Postharvest treatment with Stadium, applied prior to storage, effectively reduced silver scurf severity after 90 days of storage in 2 of the 4 years of the study. Our fungicide evaluation results provide updated insights for growers seeking to optimize fungicide use for silver scurf management.