The Influence of Ectotrophic Mycorrhizal Fungi on the Resistance of Pine Roots to Pathogenic Infections. I. Antagonism of Mycorrhizal Fungi to Root Pathogenic Fungi and Soil Bacteria

Antagonism of ectotrophic mycorrhizal fungi to Phytophthora cinnamomi, other root pathogenic fungi, and soil bacteria was examined. In agar plate tests, Laccaria laccata, Lactarius deliciosus, Leucopaxillus cerealis var. piceina, Pisolithus tinctorius, and Suillus luteus inhibited growth of nearly half of the 48 different fungal root pathogens. Leucopaxillus cerealis var. piceina inhibited 92% of the test pathogens. Differences in sensitivity of several isolates of P. cinnamomi to inhibitions by this symbiont were not found. Culture filtrates of L. cerealis var. piceina were inhibitory also to growth of P. cinnamomi and soil bacteria. Zoospore germination was inhibited completely in filtrates of this symbiont.…