THE FUNGICIDES TERRAZOLE AND TERRACLOR AND THE NEMATICIDE FENAMIPHOS HAVE LITTLE EFFECT ON ROOT COLONIZATION BY GLOMUS-MOSSEAE AND GROWTH OF COTTON SEEDLINGS

The effect of three pesticides on the initiation and early development of arbuscular mycorrhiza in cotton was examined in experiments under controlled conditions. The fungicides Terrazole and Terraclor initiall y inhibited mycorrhizal infection of roots of cotton. The inhibition d isappeared after 4 weeks, and neither fungicide had a lasting effect. The nematicide Fenamiphos slightly increased shoot dry weight at 6-10 weeks from planting and had no effect on mycorrhizal infection. We con clude that these pesticides have no sustained, detrimental effect on m ycorrhizal infection or growth of cotton seedlings when applied at rec ommended rates.