Molecular Soil Biology 2025, Vol.16, No.2, 73-82 http://bioscipublisher.com/index.php/msb 74 one of the most practical and economic ways. Screening disease resistant varieties and applying them to the planting process can reduce disease damage, reduce pesticide use, and maintain yield and quality (Scortichini, 2022; Buirs and Punja, 2024). This study focused on the disease problems encountered in the Off-season Cultivation of Leonurus japonicus, screened the germplasm materials with strong disease resistance and stable growth traits, and combined with the field planting experiment, explored its performance in practical application. The study also focused on the improvement of cultivation management measures and environmental control measures, aiming to improve the growth quality and efficacy performance of Leonurus japonicus in unsuitable seasons, promote its stable production, meet market demand and improve planting efficiency. 2 Major Diseases of Leonurus japonicus var. hunanensis and Their Impact 2.1 Common diseases Leonurus japonicus is the whole grass of Leonurus japonicus at seedling stage, belonging to Labiatae (Figure 1) (Wang et al., 2023a). In practice, powdery mildew is the most serious disease. The disease is caused by the fungus Podosphaera xanthii. When it occurs, a layer of white powder will appear on the surface of the leaves and stems. With the development of the disease, the white spots continue to spread, the leaves become weak, the photosynthetic efficiency decreases, and the plants gradually lose vitality. Powdery mildew is easy to occur in the weather conditions of high temperature in the daytime and high humidity at night. If the infection range is large, not only the yield will be reduced, but also the synthesis of important components such as alkaloids in plants will be reduced, thus reducing the quality of medicinal materials (Cho et al., 2013). Figure 1 Leonurus japonicus seedlings (Adopted from Wang et al., 2023a) Downy mildew is also common, and generally occurs in low temperature and high humidity climatic conditions. At the initial stage of infection, yellow or chlorotic patches will appear on the leaf surface, and gray white mold layer will grow on the back of the leaf. In off-season cultivation, especially in rainy days or humid days, downy mildew is particularly prone to outbreak. Such diseases directly affect the normal development of plants, hinder the synthesis of effective components such as Leonurus japonicus, and weaken the medicinal effect (Liang et al., 2018). Root rot is one of the most troublesome problems in off-season cultivation, which is mainly caused by soil fungi such as Fusariumspp. and Pythium spp. (zimowska, 2008). After infection, the root will become black and rotten, and the plant is difficult to absorb water and nutrition, and gradually wither. In the soil with poor drainage or long ponding time, the incidence increased significantly, affecting the survival rate and harvest of planting (Sun et al.,
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