Behaviour of Fungi Antagonistic to Sclerotinia sclerotiorum on Plant Tissue Segments

Summary: To assess the ability of fungi antagonistic to Sclerotinia sclerotiorum to inhibit the formation of sclerotia and to grow through plant tissue from cut surfaces, a plant-tissue-based system has been developed using celery, lettuce and tomato segments. Pythium oligandrum consistently showed no ability to grow through plant tissue or prevent sclerotium formation whereas Gliocladium roseum and three isolates of Trichoderma harzianum showed significant ability to grow through plant tissue and significantly decreased the production of sclerotia. Treatment of the plant tissue with G. roseum or T. harzianum 24 h before, or at the same time as, application of S. sclerotiorum gave significantly greater inhibition of sclerotium formation than did treatment 24 h after application of S. sclerotiorum. Of the fungi tested, G. roseum had the greatest ability to grow through the tissue and T. harzianum WT6 the greatest ability to inhibit sclerotium formation.