Primary Mode of Action of the Novel Sulfonamide Fungicide against and Field Control Effect on Tomato Gray Mold.

is considered an important plant pathogen and is responsible for significant crop yield losses. With the frequent application of commercial fungicides, . has developed resistance to many frequently used fungicides. Therefore, it is necessary to develop new kinds of fungicides with high activity and new modes of action to solve the increasingly serious problem of resistance. During our screening of fungicide candidates, one novel sulfonamide compound, -(2-trifluoromethyl-4-chlorphenyl)-2-oxocyclohexyl sulfonamide (), has been found to exhibit good fungicidal activity against . In this work, the mode of action of against and the field control effect on tomato gray mold was studied. had good control against resistant to carbendazim, diethofencarb, and iprodione commercial fungicides in the pot culture experiments. SEM and TEM observations revealed that could cause obvious morphological and cytological changes to , including excessive branching, irregular ramification or abnormal configuration, and the decomposition of cell wall and vacuole. induced more significant electrolyte leakage from hyphae than procymidone as a positive control. had only a minor effect on the oxygen consumption of intact mycelia, with 2.15% inhibition at 50 μg/mL. In two locations over 2 years, the field control effect of against tomato gray mold reached 83% at a rate of 450 g ai ha, better than the commercial fungicide of iprodione. Moreover, toxicological tests demonstrated the low toxicological effect of . This research seeks to provide technical support and theoretical guidance for to become a real commercial fungicide.