Management of chocolate spot disease in faba bean plants by using biological control means

Abstract This study was conducted in Nubaria city, EL-Behira Governorate, Egypt, during two winter growing seasons (2021/22 and 2022/23) to estimate the efficiency of different antagonists — Trichoderma album, T. atrovirde, T. hamatum and T. harzianum (30x106 spore/ml), as well as with the two commercial biocide products, including Blight Stop and Bio Zeid in controlling chocolate spot of bean plants on a naturally infected farm that has a history of high infection with the fungus Botrytis fabae, which causes brown spot disease which causes a decrease in productivity. In vitro, T. atroviride significantly caused the highest reduction of mycelial growth being 90.00 % followed by T. harzianum (86.67 %) and T. T. album (83.89%) on the average. In vivo, all tested antagonists significantly reduced disease incidence and severity of Botrytis fabae in both seasons 2021/22 and 2022/23. T. atroviride showed the highest efficacy bioagent (73.55 and 85.15%) followed by T. harzianum (72.55 and 81.22%) in controlling B. fabae of faba bean plants during two seasons 2021/22 and 2022/23, respectively. In addition, the results also showed that all tested bio-inducer treatments had an impact on yield components and increased levels of chlorophyll, protein%, phenols, flavonoids, peroxidase (PO), polyphenoloxidase (PPO), chitinase, and -1, 3-glucanase activities compared to control treatment in both seasons. In this regard, Spraying T. atroviride showed the highest efficacy bioagent followed by T. harzianum. On the other hand, T. hamatum showed the lowest efficacy in comparison with control treatment during the two growing seasons.