MANAGEMENT OF PURPLE BLOTCH DISEASE ON ONION

Abstract

Alternaria porri (Ellis). Ciffen causes serious problems in onion plants. It is transmitted with naturally infected seeds and bulbs from the previous crop to infect the new flower stalk of the next crop. Also, onion bulb infection decreases seed vitality. Infected sample were collected from four locations; Giza, Sharkia, Qalyubia and Menofia governorates to measure disease severity. A survey for occurrence and frequency of most dominant fungal associated with purple blotch disease on onion was carried out. Alternaria porri has the most occurrence and the greatest frequency, so the Qalyubia governorate is the most of frequent for A. porri. Study different stages of onion growth; seeds, leaves and blubs infected has been investigated highest load of these parts of A. porri. The present thesis is mainly focused on purple blotch diseases of onion study deals with various approaches of purple blotch diseases of onion such as cultural and morphological characteristics, the interaction between host and pathogen, transmission seed pathology, and the yield losses and control measures, the antagonistic effect of various bioagents and antifungal activity of different plant extracts has been studied to control fungal diseases of onion. An in-vitro study has done to achieve the most effective treatments to be applied in pots and field of onion to decrease infection and meet exportation standards. The botanical treatments carried out, aqueous extract at 5%and 10% concentration, and oil extracts at 50ppm and 75ppm concentration; the bioagents treatments as Trichoderma sp., Chaetomium sp., Bacillus sp. and Actinomyces sp.; and fungicides treatments as Score, Dithane M45 and Achook have a significant action against the mycelial growth of the fungus compared to control.