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.

Dazomet (DZ) is a soil fumigant that has been used for decades at many countries, however it was reported to have caused phytotoxicity and reduced crop yield in many countries. In this experiment, in order to clarify whether the diameter of DZ is related to phytotoxicity, this research investigated the degradation rate of DZ with different diameter ranges under three soil types held at 15, 20 or 30% soil water content at 4, 15, 25 or 37 °C, and monitored concentrations of methyl isothiocyanate (MITC) produced when Shunyi soil was fumigated with DZ using the different particle sizes ranges. When the soil water content and temperature increased, the degradation rate of DZ with different particle sizes accelerated. However, the degradation rate of DZ with large particle sizes was still lower than small particle sizes. NO₃⁻-N, available phosphorus (AP), available potassium (AK), pH and silt content in the soil were all significantly positively correlated with 400 μm DZ. However, organic matter (OM) and sand content produced the opposite result. The maximum concentration of MITC produced by 100–300 μm of DZ in 25 °C Shunyi soil at 30% water content were 102.2 mg/kg at 24 h. DZ produced peaks significantly higher and earlier at 30% than at 20% soil water content. We recommend selecting DZ manufactured with particle in the range of 100 to 300 μm, fumigating at about 25 °C and ensuring that about 30% soil water content is present in the soil immediately after fumigation.

This study investigates the uptake, translocation, and pathogen control efficacy of ethylicin in tomato plants using a combination of indoor root irrigation, spraying, and field root irrigation experiments. The results indicate that ethylicin shows dual-directional translocation in tomato plants. On the third day after foliar spraying, ethylicin was detected in the roots at a concentration of 2.93 mg/kg, indicating downward movement. On the third day after root irrigation, ethylicin was detected in the leaves at a concentration of 3.44 mg/kg, confirming upward movement. In the field experiments, ethylicin was absorbed and transported to the upper leaves within six hours of root irrigation at a concentration of 3.85 mg/kg for a single-agent ethylicin and 5.87 mg/kg for an ethylicin–oligosaccharin compound. These results indicate that oligosaccharins enhance the absorption of ethylicin. Ethylicin residue dissipated by the fifth day. No ethylicin was detected in the untreated controls. Root irrigation during the growing period showed an effective reduction of Fusarium spp. and Phytophthora spp. populations in the soil and control of soil-borne diseases. These findings provide theoretical support for the efficient application of ethylicin in the field.

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.