EFFECT OF A SYNTHETIC PYRETHROID ON THE GROWTH OF ECTOMYCORRHIZAL FUNGI AND MYCORRHIZA FORMATION IN PINUS-PATULA

Th effect of fenvalerate 20% EC (a synthetic pyrethroid) on the growth of two ectomycorrhizal fungi, Thelephora terrestris and Laccaria lacc ata, was studied in vitro. In the case of T. terrestris, mycelial grow th was promoted at lower concentrations of the insecticide but inhibit ed at higher concentrations; mycelial growth of L. laccata decreased w ith increase in concentration. The effect of the insecticide at three concentrations (0.25, 0.5, 1.5 ppm) was also studied on ectomycorrhiza l formation in 4-month-old seedlings of Pinus patula in nursery trials . At lower concentrations the insecticide had no significant effect on mycorrhizal formation.