A precisely targeted application strategy of dipping young cucumber fruit in fungicide to control cucumber gray mold

Gray mold is a ubiquitous destructive plant disease found worldwide. To avoid the shortcomings of conventional spraying systems for controlling this disease, such as high selection pressure on Botrytis cinerea for resistance and fungicide waste resulting from spray drift, a precisely targeted application strategy of dipping young cucumber fruit in a mixture of fungicide and forchlorfenuron (plant growth regulator, PGR) during the bloom period to control cucumber gray mold was developed in the current study.

Without leaving above-limit residues in cucumber fruits, dipping in fludioxonil at 30 mg L^-1 provided a greater efficacy (85.4%) against cucumber gray mold than did spraying at 100 mg L^-1 (76.4%). Importantly, fludioxonil mixed with forchlorfenuron from 25 to 35 mg L^-1 increased the yield of cucumbers by 26.2-36.7% compared to dipping fruit only in forchlorfenuron. The increased yield may be a benefit of controlling gray mold.

Dipping fruit in fungicides and PGRs seems to be a potential precisely targeted application strategy to not only control cucumber gray mold effectively but also, through the action of PGRs, to increase the cucumber yield. This novel application method is believed to have a bright prospect in cucumber production in Chinese solar glasshouses. © 2018 Society of Chemical Industry.