Cultivar, Plant Height and Fungicide for Integrated Control of Ramularia Spot and Increased Cotton Yield

Cotton is a crop with a high economic value, usually sprayed with large amounts of pesticides to control pests and diseases. Ramularia spot is a foliar disease that cause early defoliation and can compromise cotton yield; however, there is a need of information about the interaction of cultivars and plant height as a tool to improve ramularia control and increase yield. The objective of this study was to evaluate the effects of the interaction between plant height, cultivar, and fungicides applied to the severity of the leaf spot and cotton yield. The experiment was carried on during the 2014/15 crop season in Chapadão do Sul, MS, Brazil. A randomized complete block design in a 2 × 3 × 3 factorial scheme was used, where the factors were plant heights (1 and 1.5 m), cultivar (FMT 701, FM 975, and FM 944) and type of fungicide (Negative control , FT1, and FT2). The fungicidal treatments consisted of sequential sprays of different fungicides, including the triazole, strobilurin, and carboxamide groups, recommended to farmers. The cultivar FM 975 showed greater ramularia spot progress curve when grown at 1 m height and without fungicide spray. The fungicides were efficient in reducing the severity of the ramularia spot and their use in shorter plants (1 m) increased yield. The cultivar FM 975 had the highest total yield.