Efficiency of Some Abiotic and Biotic Agents on Vicia faba L. Rust and Chocolate Spot Diseases

Abstract

A variety of soil- and air-borne pathogens can attack faba bean plants, leading to rust and chocolate spot diseases that seriously affect plant yield. This study aims to evaluate the efficacy of certain essential oils as abiotic agents and biotic agents as safe alternatives to fungicides for both diseases. Double foliar applications of these essential oils and biotic agents significantly reduced the development of faba bean rust and chocolate spot incidence. The highest reduction in faba bean rust (92.7%) was achieved after spraying with jojoba oil, followed by 88.9% and 85.3% for grape and bitter orange oils, respectively. Furthermore, biotic inducers such as Bacillus subtilis, Trichoderma harzianum, and Saccharomyces cerevisiae reduced chocolate spot incidence by 100.0%, followed by a 72.3% reduction with bitter orange, thyme, black seed, and jojoba oils. The second foliar treatment with B. subtilis, T. harzianum, black seed oil, jojoba oil, and chitosan increased faba bean protein contents more than the first treatment. Individual foliar sprays with chitosan and grape oils enhanced catalase (CAT) specific activity, with the highest levels achieved after the first and second foliar applications, respectively. S. cerevisiae and lemongrass oil induced the highest peroxidase (POD) specific activity after both spray applications. Black seed oil induced the highest chitinase (CHIA) specific activity after the first foliar application, while lemongrass oil achieved the highest level after the second spray. The second foliar application of moringa oil, black seed oil, jojoba oil, chitosan, B. subtilis, and S. cerevisiae stimulated the formation of new protein bands in treated faba bean plants, which were not found after the first application. Therefore, the abiotic and biotic agents used in this study could be considered good and safe alternatives for resistance against these foliar diseases, reducing the harmful effects of synthetic fungicides.