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.