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，巴西柑橘种植业因植物病原真菌链格孢菌柑橘专化型（Alternaria alternata f.sp. citri）的侵染，蒙受了生产力与果实品质的双重严重损失，该病原菌引发的病害被称为链格孢褐斑病（Alternaria brown spot, ABS）。当前该病的防治仍依赖大量农用化学品的施用，每个生殖周期最多需喷施20次药剂。本研究评估了红三叶（Trifolium pratense）与小果胡萝卜（Daucus pusillus）的发酵提取物用于体外（in vitro）和体内（in vivo）防治ABS的效果。经40%浓度高压灭菌处理的发酵提取物可实现100%的抑菌效果，而两种植物的粗提物均无抑菌活性。体内实验中，未经高压灭菌处理的红三叶发酵提取物的预防性施用方案效果最优，对病害发生的抑制率达93%。