Sensitivity of soybean seed borne pathogens to eight fungicides

In order to screen fungicides with good inhibitory effect on pathogens carried by soybean seeds in Inner Mongolia, the sensitivity of four genera isolated from the interior of soybean seeds and eight genera isolated from the surface of soybean seeds to fungicides with different modes of action was measured by mycelium growth rate method. The results showed that the three 14α-demethylase inhibitors prochloraz, tebuconazole, and mefentrifluconazole had a good inhibitory effect on all tested strains, among which mefentrifluconazole had the strongest inhibitory efficacy with the EC₅₀ values against all tested pathogens less than 3.73 μg/mL. The succinic dehydrogenase inhibitor fluopyram had a good inhibitory effect on some pathogens. The mitochondrial complex III inhibitor azoxystrobin showed a good inhibitory effect on most pathogens except Alternaria and Boeremia, with the EC₅₀ values ranging from 0.01 to 5.53 μg/mL. The EC₅₀ values of uncoupling inhibitor fluazinam against other pathogens were all less than 3.39 μg/mL, except for Plectosphaella isolated from the seed interior. Carbendazim and fludioxonil had good inhibitory effects on most pathogens but had poor inhibitory effects on Alternaria and Plectosphaella. In summary, it is recommended to use the compound of 14α-demethylation inhibitors such as prochloraz, tebuconazole, mefentrifluconazole, and other agents for seed treatment to control the diseases caused by soybean seed-borne pathogens.