IN-VITRO EVALUATION OF FUNGAL ISOLATES FOR THEIR ABILITY TO INFLUENCELEAF RHEOLOGY, PRODUCTION OF PSEUDOTHECIA, AND ASCOSPORES OF VENTURIA-INAEQUALIS

As part of an ongoing research project on biological control of apple scab, this study presents a novel approach for the in vitro selection of potential antagonists of the saprophytic phase of Venturia inaequal is. A collection of forty-two fungal isolates were tested for their in vitro ability to degrade apple leaf tissue, inhibit pseudothecia, and ascospore production. The inhibition of ascospore production cannot a lways be linked reliably with leaf degradation or the evaluation of ps eudothecia production. Consequently, ascospore production was retained as the most useful screening parameter. Six isolates proved to signif icantly reduce the ascospore production of Venturia inaequalis. Two we re as effective as Athelia bombacina, a previously reported antagonist of pseudothecia formation and inhibited over 98% of the ascospore pro duction. These new organisms are now available for future field tests. Future selections from a large collection of fungal and bacterial sap rophytes can now be based on a reliable and simple in vitro screening method.