Fungicidas aplicados no plantio para controle de Rhizoctonia solani em batata

Abstract

Potato (Solanum tuberosum L.) ranks third among the most important crops in the world. This food crop is the target of several diseases, those that are caused by soil pathogens are usually difficult to control, as is the case of Rhizoctonia solani, which is one of the main diseases and its causative agent causes significant losses to farmers. Control is performed with an integration of different measures, including in-furrow fungicide applications. The aim of this study was to evaluate the efficacy of fungicides in the control of R. solani. The experiment was conducted using a randomized block design, with 10 treatments and 4 replications, being: T1 Tifluzamida (1,6 L ha-1); T2 Tifluzamida (1,6 L ha-1) + Fluazinam (2 L ha-1); T3 Tifluzamida (2 L ha-1); T4 Tifluzamida (2 L ha-1) + Fluazinam (2 L ha-1); T5 Tifluzamida (2 L ha-1) + Fluazinam (2 L ha-1) + Bioestimulante (2 L ha-1); T6 Flutolanil (2 L ha-1); T7 Flutolanil (2 L ha-1) + Fluazinam (2 L ha-1); T8 Pencicurom (3,2 L ha-1); T9 Carboxina + Tiram (4 L ha-1) and T10 negative control. The Asterix variety was used. Were evaluated incidence of symptoms on stems, number of lesions on leaves, diameter, and length of stems. The tubers were harvested and classified as G (large), M (medium) and P (small). Contaminated tubers were accounted for, and grades were attributed from 0 to 5 for the degree of severity. In the morphological evaluations, there were no statistical differences. In the evaluation of number of lesions present in the leaves, treatments 1, 2, 8 and 9 were similar to each other, presenting the highest number of lesions per leaves. Regarding percentage of infected tubers, treatments 2, 5 and 7 had the lowest means. When looking at productivity, treatment 2 had the highest average productivity of the small class, while treatment 5 achieved the highest average of Commercial Total. Therefore, it was concluded that the number of lesions present in the leaves did not affect the development of the stems. Treatment 5 showed reduction of the percentage of infected tubers, as well as of the severity of infection. When it comes to productivity, treatment 5 provided the highest average of the Commercial Total class.