Integração entre controle genético e químico sobe o progresso da ferrugem asiática e a produtividade da soja

Abstract

The objective was to evaluate the genetic control (tolerance) integrated to the chemical control of the asian soybean rust (ASR) and the effects of these measures on crop productivity. The experiment was conducted in Erechim / RS, in the 2016/17 and 2017/18 harvests, under a randomized block design, in subdivided plot scheme (cultivars, in the plots; and fungicides in the subplots), with 4 replicates. The following cultivars were used: BMX Vanguarda (without ASR tolerance); TMG 7062; TMG 7262; and TMG 7161, ASR tolerant ("Inox"). The fungicide used were: T1) control (without application of fungicides); T2) azoxystrobin + benzovindiflupir; T3) difenoconazole + cyproconazole; T4) trifloxystrobin + prothioconazole; and T5) epoxiconazole + fluxapyroxad + pyraclostrobin. Four fungicide applications were carried out at the V6; R1; R5.1; and R6 stages. During the conduction of the experiment, to calculate the area below the disease progress curve (AUDPC), the severity of the disease was evaluated, with intervals of 7 days, in a random sample of 10 trifoliate leaves per plot. After the harvest, the yield components were determined: number of grains per plant, weight of one thousand grains (g), and the productivity (kg ha-1). In the 2017/18 crop the difenoconazole + cyproconazole fungicide was not efficient for ASR control. The soybean cultivars TMG 7062, 7161 and 7261 delayed the disease progression, however only cv. TMG 7161 presented tolerance under the presence of the inoculum in the 2016/17 and 2017/18 harvests. The association between chemical and genetic control is shown to be efficient in ASR control.