Effectiveness of some biological control agents and agricultural practices in controlling pea leaf blight caused by Ascochyta spp. under field conditions

Abstract

Ascochyta blight is one of the most common diseases that threaten pea and cause severe crop losses. The research is concerned with the integrated control of this disease by studying the effect of biological control agents with inorganic salts, planting dates and planting distances, especially in light of climate change and the impact of these factors on the spread of the disease. In this study, two bacterial strains Bacillus megaterium and Pseudomonas fluorescens as biocontrol agents; potassium carbonate and sodium carbonate were evaluated with the effect of planting dates, where the first date was at the beginning of October, and the second date was at the beginning of November. Also the distance between the irrigation lines (0.75 and 1.5 meter) in two successive seasons 2020/2021 and 2021/2022 under the conditions of the Dakhla Oasis, the New Valley Governorate. The best results were with the first date of planting and a planting distance of 1.5 meters, which led to a significant reduction of disease severity, with a significant increase in traits associated with vegetative growth. Also, treatment with Pseudomonas fluorescens led to an increase in vegetative growth and plant height compared to treatment with Bacillus megaterium. By studying the interaction between planting dates with biocontrol agents, it led to a significant decrease in disease incidence and severity, with a significant increase in vegetative growth. Also, there was no significant effect with interaction between planting dates and planting distances, while it had a significant effect on the incidence and severity of infection. Bacterial isolates used in this study with mineral salts contributed to increasing plant growth rates and reducing ascochyta blight infection rates. Further studies can be conducted to include these treatments within the integrated control programs for Ascochyta blight on pea.