Detection of antifungal activity of plant extracts on Alternaria citrus

ABSTRACT For approximately 15 years, Brazilian citriculture has suffered considerable losses in productivity and fruit quality as a result of the attack by the phytopathogen Alternaria alternata f.sp. citri, which causes Alternaria brown spot (ABS). The disease control is still performed with the massive use of agrochemicals, reaching up to twenty applications per reproductive period. The present study evaluated the efficiency of in vitro and in vivo ABS control by using fermented extracts of Trifolium pratense and Daucus pusillus as a means to control the disease. Fermented extracts autoclaved at 40% showed 100% inhibition, while the crude extract of both plants had no inhibitory effect. In vivo, the best results were found with the preventive test of non-autoclaved Trifolium pratense, which inhibited the onset of the disease by 93%.

摘要 近15年来，巴西柑橘栽培产业因植物病原菌链格孢菌柑橘专化型（Alternaria alternata f.sp. citri）的侵染遭受了严重的生产力与果实品质损失，该病原菌可引发链格孢褐斑病（Alternaria brown spot, ABS）。目前该病防治仍依赖大量施用农用化学品，每个生殖周期最多需喷施20次药剂。本研究评估了利用红车轴草（Trifolium pratense）与细叶胡萝卜（Daucus pusillus）的发酵提取物防治ABS的离体与活体防控效果：经40%浓度高压灭菌处理的发酵提取物可实现100%的病原菌抑制效果，而两种植物的粗提物均无抑制作用；活体试验中，未经高压灭菌处理的红车轴草提取物的预防性施用效果最佳，可将病害发生抑制93%。