To evaluate the performance of acibenzolar-S-methyl (BTH), alone and mixed with mancozeb, chlorothalonil and metaxyl-M+chlorothalonil, for the control of potato late blight, two experiments were carried out in commercial crops in the counties of Pilar do Sul (cv. Baraka) and Bragança Paulista (cv. Asterix), state of São Paulo, Brazil, from May to August and August to October 2001, respectively. The experimental design was of randomized blocks with four replications, with each plot measuring 25 m². A total of 10 sprayings was done at 5- to 10-day intervals with a backpack sprayer using a 5-nozzle (TXKV26) spray wand, constant pressure of 4 bars (58 psi) and average volume of 800 L/ha. Evaluations were done in regard to the severity on the leaves (0 to 100%), on the stems (score from 1 to 5) and the commercial yield of tubers. BTH presented expressive effects of control when used alone and in mixture with contact and systemic fungicides. Highest yield was verified for the mixture of BTH with mancozeb and chlorothalonil.
Phytophthora infestans; chemical control; plant activator; BTH
