Biological Control of Chocolate Spot Disease of Faba Bean Using some Bioagents under Field Conditions

摘要

Chocolate spot disease caused by Botrytis fabae Sard is one of the most yield limiting constraints of faba bean (Vicia faba L.) in the world as in Egypt. Under vitro conditions, all tested bioagents showed significant reduction in the growth area of B. fabae. The highest reduction of fungus growth area was obtained with Trichderma harzianum, Bacillus subtilis and Ampelomyces qusisqualis which reduced the growth area by 79.3, 62.6 and 60.3% respectively. At high culture filtrate 75% the same trend was shown as, T.harzianum and A.qusisqualis followed by T.viride caused 47.4, 42.6 and 41.1% reduction of Botrytis faba growth, respectively. Under greenhouse conditions, each of culture filtrate 0f T. harzianum, A. qusisqualis and T. viride at 50% concentration reduced the disease severity by 30.3, 35.0 and 36.8% after five days of treatment. Under field conditions, spraying faba bean plants with P. fluorescens, B. subtilis at concentration (2.8x108cfu ml ) and T. viride at concentration (2.5x105 pore/ml) reduced the disease severity more than 57.4%. During the growing season 2009-2010, faba bean plants treated with each of the fungicide Diathin M45 and biocides B. subtilis P. fluorescenand T. harzianum gave the highest seed yield / plot; the highest hundred seed weight (gm) and the highest seed yield ton / fed. as compared with the control treatment. The obtained data can be considered a step in the new area of the safe usage of biocides in controlling chocolate spot disease without polluting the environment.