A New Management Approach for Walnut Anthracnose Based on Reuse of Fermented Vegetable Residues

ABSTRACT Walnut anthracnose, primarily caused by Colletotrichum gloeosporioides , poses a significant threat to walnut production. This study presents a novel and sustainable strategy for managing walnut anthracnose by reusing fermented vegetable residues (jiaosu). Repeated, preventative soil applications of four types of jiaosu derived from wax gourd, pumpkin, Chinese cabbage and cabbage were evaluated for their efficacy against anthracnose and impact on soil health in a pot trial. Pumpkin jiaosu exhibited the strongest disease‐suppressive effect, significantly reducing disease severity at 15 days post‐inoculation. The mean leaf lesion in treated walnut seedlings (0.67 cm) was only 28.38% of the control plants (2.36 cm). Soil application of jiaosu enhanced chlorophyll and soluble protein content, increased polyphenol oxidase activity and mitigated cell membrane damage and reactive oxygen species accumulation in walnut seedlings. Jiasou application also significantly improved soil properties, including organic matter, available nitrogen, available phosphorus, alkaline phosphatase and urease. Organic matter content increased from 8.84 to 10.95 g/kg following treatment with Chinese cabbage jiaosu. Microbial community analysis revealed that pumpkin jiaosu enhanced soil microbial diversity and that the decline in Acidobacteria abundance under pathogen stress was alleviated. Field trials further demonstrated a significant increase in Firmicutes abundance at 60 days after pumpkin jiaosu application. These findings indicate that reusing fermented vegetable residues—particularly pumpkin jiaosu—offers an eco‐friendly and effective approach for controlling walnut anthracnose and enhancing soil health.