CONTROLE DA PODRIDÃO NEGRA DO RELHO COM O USO DE FERTILIZANTE DE COBRE

Abstract

Cabbage is a vegetable belonging to Brassicaceae family of economic importance and high nutritional value in human consumption. This vegetable has rusticity, easy handling, and production. Black rot, caused by the bacterium Xanthomonas campestris pv. campestris, is the main disease damaging the Cabbage crop with losses that can reach 60% in production. The search to control measures has been a constant challenge, and adopting preventive measures such as crop rotation, removal of crop residues, treatment of seeds, and use of pathogen seeds are recommended. After the beginning of the epidemy, there are few effective measures for disease control. Thus, this study aims to evaluate the control of black rot in cabbage using leaf fertilizer that has bioactive copper complex and amino acids in its composition. Two trials were carried out, the first one from December 30, 2016 to May 6, 2017 and the second one from October 9 to February 13, 2018, following the experimental design of randomized blocks with five replicates. The treatments consisted of evaluating the commercial product in the solution, at the concentration of 0.25%; 0.50%; 0.75%; and 1.0%. All treatments were compared to one control treatment using water alone (0%) and to one treatment using copper hydroxide application (0.03%). The applications started fifteen days after transplantation and repeated every two weeks until ending the crop cycle. The rot natural event was evaluated without pathogen inoculation, considering the record of the disease in the area. The severity of the disease was evaluated taking into account the diagrammatic scale representing the injured leaf area. Productivity (fresh mass), compactness, and lateral and transverse diameters were also evaluated. There was no black rot event in the first trial. In addition, treatment effect on the evaluated production components was not found. In the second trial, the disease event was found in all treatments. Copper-based leaf fertilizer and amino acids lowered the severity of black rot in cabbage. Concentrations below 0.5% are the most appropriate, because above this value phytotoxicity can occur to the plant and compromise the cabbage head development, its quality and its productivity.