Efficacy of certain plant extracts on controlling bean rust

The water extracts of basil, henna, lemongrass, marjoram, and thyme were used at three concentrations (S/2, S/4, and S/8) to study their impact on Uromyces appendiculatus (Pers. ex Pers.), the causative agent of bean rust in vitro and at S/2 concentration in vivo, in the presence of the fungicide Domark 10 EC at 0.5 ml/ L as check. In vitro, all treatments reduced the germination percentage, and the inhibition increased with concentration. Domark emerged as the most potent agent, inhibiting spore germination by 91.9%, followed by lemongrass with a germination inhibition rate of 76.0% at S/2 concentration. In vivo evaluations conducted in Khatatba, Menoufia Governorate, Egypt during the agricultural seasons 2022-2023 and 2023-2024 underscored the substantial benefits of these treatments not only in mitigating the frequency and severity of U. appendiculatus infections but also in a significant increase in crop yield and an elevation in total carbohydrates, protein content, and phenolic enzyme activities in bean plants, including peroxidase, polyphenol oxidase, and phenylalanine ammonia lyase. Among the tested extracts, lemongrass outperformed others, followed closely by marjoram, while basil ranked the lowest in efficacy. These findings underscore the potential of both chemical and natural treatments in managing Uromyces appendiculatus. The superior performance of lemongrass and marjoram highlights their relevance in integrated disease management strategies, providing valuable options for enhancing nutritional quality and bean yield.