biological control

Clarireedia jacksonii sp. nov. Formerly Sclerotinia homoeocarpa F.T. Bennett, the causal agent of dollar spot (DS), is the most destructive pathogen in turfgrass. Symptoms appear as circular patches 10-40 mm in diameter with small tan lesions surrounded by a darker band, sometimes presenting an hour glass appearance. A multi-year study was initiated with the objective of determining the efficacy of biological control agents (BCA) and tank mixes of BCA’s and synthetic fungicides on DS control. Nutrient source was also evaluated to determine any interaction with the BCA’s and tank mixes. in vitro studies evaluated the efficacy of synthetic and BCA’s for C. jacksonii control. Quarter strength potato dextrose agar was amended with ¼, ½ and full labeled rates of various products. Chlorothalonil at all rates provided greatest (> 90%) control of C. jacksonii for study duration. Biological control agents provided best efficacy at ¼ and ½ label rates. Streptomyces griseoviridis provided least efficacy and may have exacerbated formation of C. jacksonii. Preventative field evaluations for synthetic and BCA’s provided different results between two study years. In Year 1, all treatments had < 15% disease severity for the duration of the study. In year 2, disease pressure was extremely elevated. Synthetic program 1, centered on azoxystrobin + propiconazole applications and conventional fertility sources, provided best results with < 5% disease severity for the duration of the study. Reduced synthetic program 1, and synthetic program 2 followed closely with < 10% disease severity. Reduced synthetic programs were based on monthly applications of either chlorothalonil or pyraclostrobin every 30 day, alternated with biofungicide applications. Synthetic program 2 utilized rotation applications of pyraclostrobin and chlorothalonil every 14 days. Organic programs, utilizing only biofungicides and organic fertility sources, provided the least amount of control and exceeded the 15% threshold by the second month of the evaluation period.

Background: Faba bean (Vicia faba L.) is one of the most important grain legume crops in Egypt and many other countries of the world because the seeds offer a low-cost source of protein, lysine, carbohydrates, minerals, and vitamins. Chocolate spot disease is a stress-related fungal disease produced by Botrytis fabae that causes plant damage, limits photosynthetic activity, and reduces yield. Results: Trichoderma atroviride greatly reduced mycelial growth by 90.00% in vitro, followed by T. harzianum (86.67%) and T. album (83.89%) on average. In vivo, all studied antagonists dramatically reduced Botrytis fabae disease incidence and severity 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 in both seasons. In addition, the results also showed that all tested biological treatments had an impact on yield components and increased levels of chlorophyll, protein%, phenols, flavonoids, Peroxidase (PO), polyphenol Oxidase (PPO), chitinase, and -1, 3-glucanase activities compared to control treatment in both seasons. In this regard, spraying T. atroviride showed the highest efficacy as a bioagent, followed by T. harzianum. Contrary, T. hamatum showed the lowest efficacy compared to other treatments in both seasons. Conclusion: This investigation was carried out to determine the effectiveness of several different antagonists, i.e., T. album, T. atrovirde, T. hamatum, and T. harzianum (30 x 106 spore/ml), Blight Stop, and Bio Zeid, for controlling Botrytis fabae on bean plants and evaluating their effect on yield parameters, components, and quality.