Plant disease最新文献

Hyaloperonospora brassicae, the causal pathogen of downy mildew, presents significant challenges to spring mix greens production in California. Genetic resistance provides a strategy for sustainable management to reduce downy mildew infections and pesticide use in organic and conventional production systems. This study aimed to identify sources of downy mildew resistance to facilitate resistance breeding in baby kale. To achieve this, three host resistance screenings were conducted to assess the resistance of baby kale accessions against eight downy mildew isolates collected from eight distinct locations on the Central Coast of California. Artificial inoculation was performed by spraying a sporangia suspension onto baby kale plants, which were then incubated in a humidity chamber. Disease severity was assessed by examining both surfaces of each leaf for chlorotic and necrotic symptoms and sporulation and then quantified using an established rating scale. Screening of all 212 accessions revealed an average disease severity of 28%, with severities ranging from 0 to 100%. The initial subset screening showed average disease severities ranging from 2.2 to 9.4% depending on the isolate. The final subset screening demonstrated a range of 0.003 to 0.072% average disease severity among the four isolates, with 13 accessions exhibiting 100% estimated resistance probability, 11 accessions between 99.0 and 99.9%, and one accession below 99.0%. These results suggested that downy mildew could be effectively managed in baby kale through resistant varieties.

In Azerbaijan, hazelnut (Corylus avellana L.) is a crop of economical and nutritional importance. However, recent aflatoxin contamination events in hazelnut produced in Azerbaijan are posing health risks to consumers and reduce marketability. Aflatoxin and fumonisin levels were examined in hazelnuts collected at 33 farmers' stores, one month after the 2022 harvest under various storage conditions, from two regions in Azerbaijan. All hazelnut samples were contaminated both with aflatoxins (range = 1.1 to 7.2 µg/kg) and fumonisins (range = 0.12 to 0.30 mg/kg). Aspergillus section Flavi fungi were isolated and both aflatoxin producers and atoxigenic (incapable of producing aflatoxins) isolates were identified. Several members of vegetative compatibility group IT006, to which the Italian aflatoxin biocontrol isolate MUCL54911 belongs, were found to be native to Azerbaijan. In laboratory competition assays, MUCL54911 reduced aflatoxin produced by three types of Aspergillus fungi by 97.5 to 100%, which indicates that biocontrol could be an option to reduce aflatoxin in hazelnut. Future research efforts should be geared toward detecting and characterizing additional atoxigenic isolates, optimizing biocontrol application for hazelnut, and implementing agronomic and post-harvest practices to manage aflatoxin throughout the value chain. For effective implementation of integrated mycotoxin strategies, coalitions composed of farmers, research institutions, non-governmental organizations, private sector, and government agencies are needed.

Management of Xylella fastidiosa subsp. pauca (Xfp) presents significant challenges due to the lack of genetic resistance in major crops, pathogen variability and resistance development against the main antimicrobial compounds, and the lack of effective chemical compounds for control. Traditional bactericides in the EU are restricted, and copper-based products are increasingly limited due to environmental impacts. In this study the antibacterial side effects of some commercial fertilizers against Xfp were evaluated. These products, containing metal ions (mainly copper and/or zinc) complexed with phosphites and bioavailable silicon, show antimicrobial and bactericidal activities in vitro which suggest their possible use to control the pathogen, as well as enhanced plant resistance to biotic and abiotic stresses. Greenhouse and open field trials showed that they can significantly reduce disease severity and pathogen population, thus improving fruit yield. The integrated pest and disease management (IPDM) strategy, which combines these treatments with agronomic and phytosanitary vector-control measures, leads to a reduction of disease symptoms in treated plants compared to untreated ones. These findings highlight the potential of systemic fertilizers to mitigate Xfp symptoms by providing antimicrobial collateral effects and probably enhance plant defenses, since similar compounds are known to be plant defense inducers in other pathosystems. Therefore, these products offer a sustainable solution for managing plant pathogenic bacteria and improving crop health and yield. This approach is crucial for the sustainability of olive production in Xf-affected areas. However, further research is needed to optimize these strategies for long-term effectiveness under field conditions. Overall, the results emphasize the value of the collateral effects of some mineral fertilizers in a comprehensive strategy aimed at mitigating the symptoms of Xfp and safeguarding the agricultural productivity as well as the invaluable heritage of centuries-old Apulian olive trees.

Tomato yellow leaf curl virus (TYLCV) is a begomovirus (genus Begomovirus, family Geminiviridae) transmitted persistently by the whitefly Bemisia tabaci. It causes tomato yellow leaf curl disease (TYLCD), resulting in significant yield losses worldwide. TYLCD is controlled mainly by using F₁ hybrid tomato cultivars harboring the TYLCV resistance gene Ty-1. However, infected Ty-1-bearing tomato plants accumulate viral DNA, which may eventually lead to the emergence of a resistance-breaking TYLCV variant. Recently, a B. tabaci-resistant tomato line derived from the introgression of type IV leaf glandular trichomes and acylsucrose secretion from wild tomato (Solanum pimpinellifolium) was shown to effectively control the spread of TYLCV. In this study, we combined B. tabaci resistance and Ty-1-based TYLCV resistance to increase the robustness and durability of the TYLCD resistance mediated by Ty-1 in tomato plants. Specifically, we characterized and used a Group 2-like isolate of the Israel strain of TYLCV (TYLCV-IL-G2) that contributes to TYLCD epidemics in southeastern Spain. A comparison with isolates of the previously identified TYLCV variant revealed TYLCV-IL-G2 has a similar host range, but it induces a slightly more severe TYLCD in Ty-1-bearing tomato plants. Moreover, we demonstrated that acylsucrose-producing B. tabaci-resistant tomato plants can limit the spread of TYLCV-IL-G2 better than a near-isogenic line lacking type IV trichomes and unable to secrete acylsucrose. Pyramiding Ty-1-based TYLCV resistance and B. tabaci resistance provided by type IV glandular trichomes helped to decrease the effects of TYLCV on Ty-1-bearing tomato plants as well as the likelihood of TYLCV evolution in infected plants.