Effect of Biological and Chemical Control of Onion White Rot and Maintain Productivity

Abstract

FIELD experiments were conducted during winter seasons of 2016/2017 and, 2017/2018 at Qalyub, Qaluobia Governorate, Egypt. The main objective of this study to find out the efficacy of several biological and chemical treatments on controlling onion white rot disease caused by Sclerotium cepivorum as well as on the growth and productivity of onion plants. Three biological treatments including control (water application), Trichoderma asperellum (85 g/100 L-1), Pseudomonas fluorescence (500 ml/100 L-1), were applied respectively. These treatments were combined with five chemical treatments (commercial fungicides) and applied as follows: Control, Iprodione (250 g/100 L-1), Tebuconazole with Fluopyram (50 ml/100 L-1), Tebuconazole (188 ml/100 L-1), Azoxystrobin plus Mefenoxam (200 ml/100 L1). The ability for growing onion crop productivity was tested and decrease disease severity and incidence growth of white rot by the treatments were sprayed three times on plants at (40-55-70) days after planting or (19-41 BBCH) stages by using knapsack sprayer by (300 L./Fed). Results indicated that combination dipping onion seedling by T. asperellum significantly gave the highest indications of total and the marketable yield in comparison to P. fluorescence for both seasons. Moreover, the three times of spray by Iprodione applications combined with T. asperellum was increased onion crop productivity in comparison to the control treatment significantly, and the disease was lowered, disease severity, and increasing the control efficiency in both seasons. Whereas, the three times of spray by Tebuconazole applications had a moderate effect on onion crop productivity or the disease severity and incidence of Sclerotium cepivorum in comparison to the control treatment despite low to medium recovery following applications. Finally, the non-treated control treatment was the lowest of crop productivity and control of disease efficacy of onion crop.