Fungicidas de diferentes grupos químicos no controle de manchas foliares em trigo

Abstract

Chemical control is one of the main strategies for managing leaf spot diseases in wheat; however, fungicide efficacy may vary according to the products used. This study aimed to evaluate the efficacy of systemic fungicides from different chemical groups in the control of leaf spot diseases in wheat. The experiment was conducted in a randomized complete block design with nine treatments and five replications using the wheat cultivar TBIO Ponteiro. A fungicide spray program and sequential applications of fungicides with different active ingredients were evaluated during the 2025 growing season. The treatments consisted of an untreated control (T1); a spray program including the 1st application of azoxystrobin + benzovindiflupyr and azoxystrobin + cyproconazole, the 2nd application of tetraconazole + azoxystrobin, the 3rd application of tebuconazole + chlorothalonil, and the 4th application of bixafen + prothioconazole + trifloxystrobin (T2); pydiflumetofen + prothioconazole, followed by azoxystrobin + cyproconazole (T3); bixafen + prothioconazole + trifloxystrobin (T4); trifloxystrobin + tebuconazole (T5); fenpropimorph + mefentrifluconazole (T6); tetraconazole + azoxystrobin (T7); azoxystrobin + difenoconazole (T8); and picoxystrobin + cyproconazole (T9). Disease severity was assessed using the area under the disease progress curve (AUDPC), and leaf spot control (%) was also evaluated. At harvest, hectoliter weight, thousand-kernel weight, and grain yield were determined. The spray program showed the best performance, with an AUDPC of 152.60, 89.24% disease control, and a grain yield of 4,005.32 kg ha⁻¹. Among the fungicides evaluated under sequential application, fenpropimorph + mefentrifluconazole provided more than 88% disease control. It was concluded that spray programs based on the rotation of active ingredients and modes of action highlight the importance of diversifying modes of action to broaden the spectrum of leaf spot control and preserve the productive potential of wheat.