Control Efficacy of a New Fungicide Fludioxonil on Lettuce Gray Mold According to Several Conditions

Choi, Gyung Ja; Jang, Kyoung Soo; Choi, Yong Ho; Kim, Jin Cheol

Research in Plant Disease 2009;15(3):217-221.
Published online December 30, 2009.

발병 조건에 따른 fludioxonil의 상추 잿빛곰팡이병 방제효과

최경자, 장경수, 최용호, 김진철

Control Efficacy of a New Fungicide Fludioxonil on Lettuce Gray Mold According to Several Conditions

Gyung Ja Choi, Kyoung Soo Jang, Yong Ho Choi, Jin Cheol Kim

Abstract

Fludioxonil is derived from the antifungal compound pyrrolnitrin produced by Pseudomonas pyrrocinia and classified as a reduced-risk fungicide by the US EPA. The efficacy of fludioxonil for the control of lettuce gray mold caused by Botrytis cinerea was evaluated under several conditions such as growth stages of host, inoculum concentrations, and amounts of potato dextrose broth (PDB) included in spore suspension of B. cinerea. At 4-leaf stage of lettuce plants, fludioxonil applied at 2 μg/ml was more effective for the control of gray mold than at 5- and 6-leaf stages. However, fludioxonil at more than 10 μg/ml provided similar control activity in all growth stages of lettuce tested. The fungicide (10 and 50 μg/ml) also gave excellent control of gray mold on lettuce seedlings inoculated with spore suspensions of B. cinerea (2.5×105 to 2×106 spores/ml). But, control efficacy of fludioxonil (2 μg/ml) was negatively correlated with inoculum concentration. Addition of PDB in spore suspension of B. cinerea resulted in higher disease severity than non-treated control. By inoculating spore suspension including 0.5% PDB, the fungicide gave the most control activity on the disease, followed by 1% and 2% PDB. The results suggest that fludioxonil has potential to control gray mold of lettuce, but the fungicide at a concentration having moderate activity may represent low control efficacy on the disease under some conditions.

Key Words: Botrytis cinerea, Control activity, Fludioxonil, In vivo fungicidal activity, Inoculum concentration