Molecular Pathogens, 2025, Vol.16, No.3, 121-133 http://microbescipublisher.com/index.php/mp 122 understanding of the prevalence of rapeseed diseases and formulating effective comprehensive prevention and control strategies. Therefore, it is necessary to conduct a systematic review of the symbiotic occurrence patterns of major diseases in rapeseed fields. In this study, we will first introduce the types, distribution and harm of the main diseases of rapeseed, then explain the occurrence characteristics of each disease and its complex occurrence in the field, analyze the interaction relationship and mechanism between pathogens, further explore the environmental and agricultural factors that affect the occurrence of diseases, and finally summarize the comprehensive prevention and control measures in the context of multiple diseases and look forward to future research directions. Through this review, we aim to provide a reference for in-depth study of the mechanism of compound infection of rapeseed diseases and formulate coordinated prevention and control strategies for multiple diseases. 2 Overview of The Main Diseases of Rapeseed 2.1 Sclerotinia sclerotiorum of rapeseed Sclerotinia sclerotia is one of the most common and most harmful diseases in rapeseed production, and is caused by infection of the semi-aware fungus Sclerotinia sclerotiorum. Sclerotinia sclerotiorum can infect the stems, branches and horn fruits of rape plants. The typical symptom is that water-like lesions appear on the stems of the plant in the late flowering stage, which will then develop into a white mold layer, forming black horn fruits inside, causing the plant to die early and the horn fruits to shrivel. Sclerospermia of rapeseed occurs almost every year in the main rapeseed production areas such as the Yangtze River Basin and the southwest, and is one of the main limiting factors affecting China's rapeseed production. In general, the field disease rate can reach 10% to 30%, which often leads to a 10% to 20% reduction in rapeseed yield; in rainy and humid years, Sclerotinia sclerotiorum outbreaks and epidemics, and the disease rate of some fields can exceed 80%, and the yield loss may even exceed half (Michael et al., 2023). Because the rainy and oligosity of winter and spring are very conducive to the epidemic of Sclerotinia sclerotiorum, the incidence of Sclerotinia sclerotiorum in southern rapeseed production areas is increasing. Sclerotic cervix overwinters in soil with sclerotia and can survive for many years. In the early spring of the second year, ascystic cervix and ascospores are produced under suitable warm and humid conditions. Ascospores spread through wind and rain, attach to rapeseed petals and infect the plants as the petals fall off, causing stem disease. The entry of rapeseed into the peak flowering stage to the final flowering stage is a high-risk stage for Sclerotinia sclerotiorum infection (Lane et al., 2018). Cultivation conditions such as dense planting, congestion of plants, and high field humidity will aggravate the occurrence of Sclerotinia sclerotiorum. Since most rapeseed varieties lack high resistance to Sclerotinia sclerotiorum, and Sclerotinia sclerotiorum can retain soil for a long time, it is difficult to prevent and control. At present, production is mainly controlled through measures such as spraying chemical fungicides during flowering and cleaning up diseased remains after harvest, but it is still difficult to eliminate the losses caused by this disease under epidemic conditions. 2.2 Rapeseed Plasmodiophora brassicae Clubroot of rapeseed is a devastating soil-borne disease caused by the protist Plasmodiophora brassicae. It can infect the roots of cruciferous crops such as rapeseed, leading to tumor-like enlargement of the root system and obstruction of plant nutrient absorption, which manifests as dwarfing and wilting. In severe cases, the whole plant dies and does not have a strong strength (Ren et al., 2016). The disease was first discovered in Taiwan and Fujian, China in the 1920s. Since then, the scope of occurrence has continued to expand. In recent years, it has shown a rapid spread in rapeseed production areas such as the Yangtze River Basin and the southwest. According to statistics, the incidence area of rapeseed Plasmodiophora brassicae in China every year is as high as 48 million to 60 million mu, accounting for about 30% of the national cruciferous crop planting area. Plasmodiophora brassicae has become one of the most harmful diseases in China's rapeseed production. The pathogen is dormant spores that are hosted by soil and can survive in soil for more than ten years. Once the cultivated land is seriously contaminated by roots and tumours, it is often not advisable to plant host crops such as rapeseed for many years. Rapeseed can be infected by root and tumour from the seedling stage to the bolting stage, and the low temperature and high humidity soil environment is particularly conducive to the occurrence of diseases. Plasmodiophora
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