Improving Biological Control of Botryodiplodia Disease in Some Annona Cultivars
by Combining Biological Agents in Egypt

• Wafaa M. Haggag and M.A.Nofal
• Department of Plant Pathology, Davison of Agricultural Research and Biology, National Research Center, Dokki, Cairo, Egypt.
• Email: mkelany@link.net
• Tel.: +002023371362; fax: 002-02-3370931
• The Third International Conference onIPM Role in Integrated Crop management and Impacts on Environment and Agricultural Products. 26-29 November 2005, Giza, Egypt.

Abstract

During the last few years, some Annona cultivars in Egypt, especially at Behera governorate, were suffering from the incidence of diseases viz., stem purple lesions, canker lesions, blight, dieback, flowers and fruits dry or soft rot, caused by Botryodiplodia theobromae. The efficacy of six biocontrol agents i.e. Trichoderma species (Trichoderma koningii and T. hamatum), Pseudomonads bacteria (Pseudomonas fluorescens and P. putida) and Tilletiopsis yeast like fungi (Tilletiopsis minor and T. washingtonensis), separately and in combinations as first report against Botryodiplodia disease ,were tested as foliar spraying on three Annona cultivars, i.e. Balady and Abd El-Razik (A. squamosa) and Hindy (A. cherimola). In vitro studies revealed significant inhibition of B. theobromae conidial germination as well as disease severity on artificially inoculated Annona branches and fruits in the presence of aforementioned biocontrol agents. When promising biocontrol agents were applied in a mixture, disease reduction was more evident. The biocontrol agents were tested during 2003 and 2004 crop seasons in naturally infected field conditions at Noubaria, Behera Governorate. Single application and all possible combinations of two or three biocontrol agents were applied at 15 days intervals as foliar spray. Botryodiplodia disease severity and the sporulation of the pathogen were always reduced, where a biocontrol agents was applied. When Trichoderma and Pseudomonads were mixed, disease was greatly reduced in the three cultivars as compared to the single strains. The multi-strain mixture of the biocontrol agents was more effective than single or double treatments. Application of combined biological control agents also resulted in significant increase in fruit yield.