GLIOCLADIUM-VIRENS IN AN ALGINATE PRILL INEFFECTIVE AS A BIOLOGICAL-CONTROL OF FUSARIUM ROOT DISEASE IN CONTAINER-GROWN DOUGLAS-FIR

An alginate prill formulation of Gliocladium virens (GL-21) was added as a top-dressing (54 g per m(2)) or incorporated into medium (1.2 kg per m(3)) used to grow Douglas-fir seedlings in styrofoam containers. Seedlings in the top-dress treatment were similar to control seedlings ; infection and colonization by naturally-occurring Fusarium was unaff ected by treatment. Incorporated G. virens reduced seedling growth and increased occurrence and colonization intensity of Fusarium. In a lab oratory experiment, inoculating Douglas-fir seedlings with G. virens ( 10% w/w) prior to inoculation with Fusarium increased survival time wh en compared to concurrent inoculations of fungi.