Sakura crown gall, caused by the invasion of Agrobacterium tumefaciens through plant wounds, poses a significant threat to cherry trees. In this study, the distribution of A. tumefaciens was preliminarily determined by stratified sampling and qPCR detection. Vertically, the pathogen is mainly distributed in the soil layer below 20 cm, and the amount of bacteria increases at greater depths. Horizontally, they are found within a 150 cm radius from the trunk. Zhongshengmycin and Oligosaccharide–Ethylicin were applied 100 cm from the trunk at a depth of below 20 cm. In the 20~40 cm soil layer, a 600-fold diluted solution of 3% Zhongshengmycin had a relative control efficacy of 94% to 100% against Agrobacterium tumefaciens, while a 1000-fold diluted solution of 25% Oligosaccharide–Ethylicin showed a control effect ranging from 54% to 100%. Before transplantation, the soil was disinfected with dazomet and abamectin. Application rates were 35 g/m² for dazomet (98% granules) and 1 mL/m² for abamectin (1.8% emulsifiable concentrate). The disinfection effectiveness was 77~100% in the 0~60 cm soil layer.

Long-term continuous cropping aggravates soil-borne diseases and seriously affects crop growth, yield, and quality. Soil fumigation is an effective approach for reducing soil-borne pathogen pressure before crop planting, but environmentally compatible alternatives to conventional fumigants are still needed. The objective of this study was to evaluate the field efficacy of ethylicin as a soil fumigant for controlling major soil-borne pathogens under organic greenhouse production conditions and to determine its effects on soil physicochemical properties and tomato growth and yield. Two consecutive years of field trials were conducted at Yanqing Organic Park. During fumigation, the maximum soil temperature reached 50.8 °C at the soil surface and 42.6 °C at a depth of 10 cm, which may have contributed to pathogen suppression and enhanced the fumigation effect of ethylicin. Ethylicin markedly reduced the populations of Fusarium spp., Phytophthora spp., and Meloidogyne spp., with control efficacies ranging from 96.44% to 97.73%, 68.12% to 95.30%, and 72.12% to 96.91%, respectively. Fumigation also altered soil physicochemical and nutrient properties, decreasing NO₃⁻–N content and electrical conductivity while increasing NH₄⁺–N, organic matter, and available potassium. Tomato plant height, stem diameter, and chlorophyll content increased by 16.52%, 20.71%, and 6.73%, respectively, and yield increased by 35.28–38.83% over the two years. Phytophthora parasitica-associated root rot was also reduced following ethylicin fumigation, with the disease index decreasing from 3.75 ± 3.23 to 1.25 ± 2.50 in 2023 and from 5.56 ± 1.92 to 0 in 2024; no visible root rot symptoms were observed in the ethylicin treatment in 2024. Overall, ethylicin provided stable suppression of major soil-borne pathogens while improving soil nutrient conditions and tomato performance. These results support the potential of ethylicin as a pre-plant soil fumigant for greenhouse vegetable production, particularly in systems with high requirements for pesticide-residue control and environmental safety.