Impact of Alternative Safety Programs to Fungicides on Management Squash Powdery Mildew

Abstract

Microscopic examination of the conidial stage of squash (cv. Eskandrani) powdery mildew pathogen was performed. The parameters of conidia (24-40 X 16-26μ), length/width ratio (1.47) and characteristics of conidial germination confirmed that the pathogen belongs to the genus Oidium the conidial stage of Sphaerotheca fuliginae (Schlecht. Ex Fries) Poll. Three experiments were carried out under controlled greenhouse conditions to evaluate the efficacy of three plant oils, i.e. sesame oil, alovera oil and flax oil; three natural compounds, i.e. kaolin, potassium bicarbonate and whey in addition to four beneficial bacterial isolates, i.e. B. subtilis, B. vallismortis, P. brasilensis, and P. polymexa against squash powdery mildew. Emulsified sesame oil at 0.3%, kaolin at 6% and P. polymexa (9x108 cfu/ml) were found to be more effective in reducing severity of powdery mildew to 7.42; 8.08 and 23.96%, respectively, against 35.71% in the untreated check. Under natural conditions, rotational application programs, including T1 (Prochloraz fungicide as single repeated treatment); T2 (Procloraz alternative with kaolin) and T7 (Prochloraz alternative to a mixture of potassium bicarbonate, sesame oil and whey) were found to be more effective in reducing severity of powdery mildew to 4.59, 7.09 and 7.92%, respectively without significant differences against 41.25% in the untreated check. In conclusion, to fulfil effective control of powdery mildew, the use of fungicides must be integrated carefully with environmentally friendly materials.