Urban production of kale (Brassica oleracea var. acephala) in Brazil: survey of diseases and factors that contribute to their outbreak

ABSTRACT Kale (Brassica oleracea var. acephala) is mostly produced by urban growers in Brazil, but little is known about the diversity and the management of diseases for sustainable urban agriculture. The present study investigated the occurrence of diseases in the urban cultivation of kale in two regions of Brazil, representing the climate conditions Cwa (Lavras - MG) and Aw (Campina Grande - PB) according to Köppen Geiger classification, as well as the factors that contribute to such occurrence. Growers in each region were visited every week during eight months while a survey was carried out on the diseases and the major crop management practices. In both regions, powdery mildew (Erysiphe polygoni) and black rot (Xanthomonas campestris pv. campestris) were the prevalent diseases. Relative humidity and high temperature were the environmental factors that contributed to increase the diseases. Management using straw mulch favored powdery mildew reduction and black rot maintenance. Consequently, kale intensive production resulted in higher black rot severity. These results demonstrated the importance of proper recommendations on management practices for urban agriculture with the aim of controlling kale diseases according to the climate conditions in the region.