Pathogen Identification and Indoor Fungicides Screening for Root Rot Disease in Tiller onion

Abstract This study aimed to identify the pathogen responsible for root rot disease in tiller onion in Nongan county, Jilin Province, China, and to screen for effective control measures using fungicides. The pathogen was isolated from diseased plants using the tissue block separation method and identified through morphological and molecular biological methods as Fusarium oxysporum. Indoor toxicity testing was conducted on 19 fungicides using the growth rate method, and the most effective agents were screened out. Results showed that nine agents had the best inhibitory effect on the pathogen, with EC50 values of less than 0.1 mg/L. These agents include 99% propiconazole, 98% difenoconazole, 99% hymexazol, 98% myclobutanil, 98% prochloraz, 98% tebuconazole, 97% thiram, 70% thiophanate-methyl and 97% pyraclostrobine. Conversely, 99% sodium trisulfate and 98% copper calcium sulphate had the least inhibitory effect, with EC50 values of more than 50 mg/L. The results provided a scientific basis for identifying and controlling root rot of tiller onion in Nongan County, Jilin Province, China.