Potencialidade de fungicidas biológicos no controle de requeima do tomateiro

Abstract

This study aimed to compare the efficiency of chemicals and biological agents in the alternative control of P. infestans in tomato hybrid Silvety. The experiment was carried out in the experimental area of the State University of Southwest Bahia, Brazil in a randomized block design with five treatments and four replications. The experimental unit consisted of 12 plants. The treatments (T) were: T1) nonsprayed check; T2) Trichoderma harzianum; T3) Trichoderma longibrachiatum; T4) metalaxyl-M + mancozeb; T5) propamocarb hydrochloride + fluopicolide, and T6) dimetamorph. Besides the evaluation of disease severity, the following variables were evaluated: number of fruits per plant, mean fruit weight and yield. The severity assessments were used to calculate area under the disease curve of the late blight progress (AACPR). The results were submitted to analysis of variance and to the Tukey test (5%). The chemical fungicides, regardless of their mode of action, gave a greater protection against late blight. Hydrochloride propamocarbe + fluopicolide and metalaxyl-M + mancozeb resulted in the lowest rates of disease foliar area, 2.6 and 4.36%, respectively, 65 days after transplant (DAT). The biological control agents T. harzianum and T. longibrachiatum showed protective efficiency against the late blight until 58 DAT. Propamocarbe + fluopicolide had the lowest value of the AACPR (31.50) and an average increase of 47% in productivity in relation to the nonsprayed treatment.