ROTACIÓN DE FUNGICIDAS PARA EL CONTROL DE Rhizoctonia spp. Y Ascochyta spp., EN Pisum sativum L., cv. EARLY PERFECTION 326

Abstract

ROTATION OF FUNGICIDES FOR THE CONTROL OF Rhizoctonia spp. AND Ascochyta spp., IN Pisum sativum L., cv. EARLY PERFECTION 326.

The diseases caused by Rhizoctonia spp. and Ascochyta spp. affect the production of peas (Pisum sativum L.), generating economic losses for producers in Mexico State. Control generally consists of the use of one or two active ingredients of synthetic origin with the same site or mechanism of action, presenting a risk for the rapid development of resistance. The objective of this study was to generate a control strategy for Rhizoctonia spp. and Ascochyta spp., in pea crops of the Early Perfection 326 cultivar. We evaluated five proposals for the rotation of fungicide sites and/or mechanisms of action, plus an absolute control. In the municipality of Joquicingo, in the southern region of Mexico State, we established a randomized complete block design with four repetitions; each treatment consisted of four rows. The treatments for Rhizoctonia spp. were: T1 (Az+Me–Tol M–Ti–Ip), T2 (Tol M–Ip–Ti–Az), T3 (Cap–Ip–Az+Me–Ti), T4 (Az+Me–Ti–Tol M–Cap), T5 (Cap–Tio M–Az–Zb) and the control. For Ascochyta spp., they were: T1 (Clo–Zb–Ip–Cb), T2 (Mz–Ip–Clo–Cb), T3 (Zb–Clo–Cb–Cy+Mz), T4 (Zb–Clo–Ip–Mz), T5 (Cb–Zb–Az–Cy+Mz) and the control. Each active ingredient was applied once every 15 days throughout the whole growing cycle. For each treatment of each disease, we determined the disease incidence (%), the area under the curve of disease progression, and the yield. For Ascochyta, we also evaluated disease severity using a validated diagrammatic scale. We performed an analysis of variance in SAS and determined the area under the curve using the program R. The results indicated that the different rotation proposals slowed the incidence for both diseases compared to the controls. For both Rhizoctonia spp. and Ascochyta spp., T5 (control) had the largest value of the area under the curve. The rotation of fungicide sites and/or mechanisms of action with the lowest incidence and disease progress curve for Rhizoctonia spp. was T3 (Cap–Ip–Az+Me–Ti) and for Ascochyta spp. were the fungicides evaluated in T3 (Zb–Clo–Cb–Cy+Mz), which also expressed the lowest level of damage. In both treatments there was higher yield in the pea crop in the southern region of Mexico State.