Plant disease最新文献

Pearl bodies are small, pearl-like structures found on the surfaces of many tropical and subtropical plant species, including Carica papaya L., that serve as a nutritious food source for arthropods, helping plants defend against herbivores. This study investigated the role of pearl bodies in viral accumulation and transmission, focusing on papaya plants infected with papaya leaf distortion mosaic virus (PLDMV), a destructive pathogen threatening papaya production. Viral analysis of pearl bodies from PLDMV-infected plants confirmed the presence of viral particles, genomic RNA, and coat protein, with quantitative real-time RT-PCR showing significant viral RNA accumulation. These findings suggest that pearl bodies act as reservoirs for PLDMV. Infectivity tests demonstrated that ruptured pearl bodies from infected plants effectively transmitted PLDMV to healthy plants via mechanical inoculation. The fragility of stalks and cell surfaces of pearl bodies facilitate their detachment or rupture during mechanical activities, potentially releasing virus-laden contents into the environment. This poses a significant risk of contamination for agricultural tools, equipment, and personnel, contributing to secondary transmission. This study emphasizes the importance of recognizing pearl bodies as an overlooked source of viral spread, highlighting the need for careful handling and targeted management strategies to reduce virus transmission risks in papaya cultivation. This is the first report of pearl bodies' involvement in virus transmission, which provides novel insights into virus epidemiology and disease management in papaya cultivation and other crops with pearl bodies.

Flutriafol drench application on March 7 without and with additional applications at 8- and 20-week intervals all consistently protected boxwood plantings pre-infected by Calonectria pseudonaviculata in two gardens in Richmond, Virginia through November 21. All drench applications were dosed at 2 ml product with 42% flutriafol and delivered in 250 ml solution per 30.5-cm shrub height in both gardens. While providing season-long protection, this drench dose also resulted in significant phytotoxicity on 30.5-cm tall 'Justin Brouwers' boxwood but not on English and common boxwood, which were 1.4 and 1.1 m tall, respectively. Once the phytotoxicity issue is resolved, only a single drench per year may suffice to protect boxwood plantings in the Mid-Atlantic, which would substantially cut the labor cost and minimize the health impacts commonly associated with current fungicide foliar sprays.

Rice stripe virus disease is one of the most devastating diseases of rice (Oryza sativa) in East Asia. The causal virus, Rice stripe virus (RSV), is persistently transmitted by the small brown planthopper (Laodelphax striatellus, SBPH). Since there is no effective treatment once rice plants are infected with RSV, it is crucial to prevent RSV infection in rice to minimize the damage. This study evaluated the effect of SBPH control with insecticides applied to the nursery box at transplanting and/or sprayed in the field on RSV infection and yield loss. We found that insecticide application either to nursery boxes or in the field reduced the percentage of diseased plants, the magnitude of damage in diseased plants, and yield loss. The combination of nursery box and field insecticide applications was the most effective at controlling the disease as it provided seamless control of SBPH from transplanting to the initial panicle formation stage. The study results offer a detailed description of the process by which chemical control of SBPH reduces damage caused by RSV. We expect these findings to be useful in developing an integrated pest management system for RSV.

Pyridaben is a novel broad-spectrum insecticide and acaricide that is effective against thrips, mites, aphids and leafhoppers. We accidentally discovered that pyridaben was able to prevent cucumber powdery mildew. In this study, we explored the inhibitory effects and underlying mechanisms of pyridaben against Sphaerotheca fuliginea. Pyridaben effectively inhibited the spore germination and mycelial growth of S. fuliginea with IC₅₀ of 10.83 mg/L and 18.28 mg/L, respectively. The spore germination, mycelial growth, and secondary spore formation of S. fuliginea was severely hindered on cucumber leaves treated with pyridaben at 20 mg/L. SEM revealed that the mycelia growing on pyridaben-treated cucumber leaves were much finer than that growing on untreated leaves. Transcriptomic analysis revealed that pyridaben had a significant impact on the ribosomal function and energy metabolism of the powdery mildew pathogen, restricting its normal physiological activities. In field experiments, the efficacies of pyridaben reached 76.48% in Zhejiang province and 78.40% in Shandong province at the rate of 225 g a.i./ha after two applications, which were comparable to the commercialized fungicides. These results suggest pyridaben is not only an insecticide but also an effective fungicide with the potential for further application in preventing and controlling cucumber powdery mildew.