Silício, cultivares e programas de controle químico no manejo de doenças foliares da cultura da cevada

Abstract

In this study was evaluated the efficacy of fungicides with different action mode on the control of foliar disease and on grain yield of barley (Chapter I). Furthermore, the supply of silicon (Si) in the soil to barley plants plus fungicide spray on leaves was evaluated on the disease suppression, yield and weight of grains (Chapter II). The experiments were conducted in the municipalities of Capão do Leão and Ronda Alta, in Rio Grande do Sul State. Seeds of barley cultivars, with industrial quality for beer, were used. The fungicides applied were products registered for the crop, and comprised the largest range of chemical groups and active ingredients possible. Si was incorporated into the soil, similar to liming procedure, by tillage. The results showed that the diseases are limiting factors of the crop and the chemical control significantly reduces the damage in the grain yield on the cultivars BRS Korbel, BRS Brau and BRS Cauê. Fungicides with the largest number of active ingredients showed greater control of the barley disease complex and gain on grain yield. The cultivars showed distinct reactions regarding to diseases resistance and variations between sites. The use of Si reduced losses caused by diseases, ensuring grain yield in all cultivars tested. The association of Si with chemical control provided gains equal to the sum of its percentage of isolated efficiency plus the chemical control efficiency. This work demonstrates the relevance of using programs of chemical control that is an approach recommended for disease management. Thus, the association of chemical control, supply of Si to plants via soil and the use of cultivars with higher resistance level is an efficient and more sustainable strategy to integrate the management of barley diseases.