Impact of conservation practices on the severity of sugarcane foliar diseases

Abstract

The Brazilian sugarcane sector has increased the adoption of conservation practices based both on mechanized harvest without burning and on the use of biological nitrogen fixation (BNF) to improve crop sustainability. However, there is no information about the impact of these practices on sugarcane diseases. This study aims at investigating the effect of conservation practices on the incidence and severity of spontaneous sugarcane diseases, considering soil tillage, planting season, residue maintenance, and sources of nitrogenous fertilizers. Two experiments were conducted, being one during the cane-plant cycle and the other carried out throughout the sugarcane cycle until the second ratoon. The simultaneous occurrences of ring spot, caused by Leptosphaeria sacchari Breda de Haan , and red rot leaf infection, caused by Colletotrichum falcatum Went, were the only diseases observed in the experiments regardless of the conservation practices. The use of reduced tillage, conventional tillage, and non-tillage as well as the planting season and the depth of the sugarcane trash layer did not influence the severity of the diseases. However, BNF reduced the severity of foliar diseases in the first and second ratoons. The overall disease severity affected the dry biomass of sugarcane in the first ratoon. The results can assist disease management strategies considering the new scenario of sugarcane production in Brazil.