Integrated control of Fusarium damping-off in conifer seedlings

Interactions among three species of ectomycorrhizal fungi (Hebeloma longica udum, Laccaria bicolor and Paxillus involutus), a litter decomposing fungus (Clitocybe clavipes), two species of root pathogens (Fusarium moniliforme and F. oxysporum), and a fungicide (oxine benzoate) were studied. In dual c ulture, C. clavipes and P. involutus reduced growth of F. moniliforme and F . oxysporum. Culture extracts of C. clavipes, L. bicolor, and P. involutus reduced mycelial growth and spore germination of F. moniliforme and F. oxys porum. Hebeloma longicaudum showed no inhibitory effect against F, monilifo rme and F. oxysporum. Two compounds, o-coumaric acid (isolated From P. invo lutus) and p-hydroxybenzoic acid (isolated from L. bicolor) reduced growth and spore germination of F. moniliforme and F. oxysporum at 100 to 1000 mu g/ml. Oxine benzoate at recommended dose reduced root rot severity and incr eased survival of lodgepole pine and white spruce seedlings against F. moni liforme and F. oxysporum. Clitocybe clavipes, L. bicolor, and P. involutus also improved seedling survival and reduced root rot severity when inoculat ed onto the seedlings alone or in combination with recommended and reduced rates of oxine benzoate.