Improving Biocontrol of Gray Mold Disease of Apple Using a Mixture of Yeast Isolates



Two yeast isolates, A4 and A5 of Candida membranifuciens and one isolate, A6 of Pichia guilliermondii were tested either separately or in mixture for their effectiveness against apple gray mold, caused by Botrytis cinerea Pres.: Fr. As regards the compatibility of the biocontrol agents, it was shown that yeast isolates were compatible with each other in liquid media. Results of the experiments carried out on germination of pathogen spore in liquid media and in dual culture showed that inhibition varied from 14.39 to 37.73% in dual culture and from 11.66 to 46% in liquid media. The lesion area caused by B.cinerea when apple inoculated with 1x108 cells/ml alone or a mixture of them was less extensive than that in the control. This is while a combination of A6+A5 was the most effective in reducing grey mold when apple incubated at 20 or 4°C. These results indicate that by using yeast mixtures, it is possible to improve biological control of the disease.