Activity of Propiconazole and Other Sterol-Inhibiting Fungicides AgainstPhymatotrichum omnivorum

Abstract

Eight sterol-inhibiting fungicides were evaluated for in vitro activity against Phymatotrichum omnivorum, the causal fungus of Phymatotrichum root rot of cotton. Mycelial growth of P. omnivorum was inhibited at concentrations as low as 0.0001 .mu.g/ml. Significant stunting of cotton seedlings occurred after replant applications of propiconazole at rates equivalent to 0.56-2.24 kg/ha. When this stunting of cotton seedlings was used as a bioassay, propiconazole was observed to persist in unsterile soil for as long as 5 mo. Results of field evaluations of propiconazole in 1982 and 1983 determined that foliar applications at 0.56-1.12 kg/ha or granular side-dress applications at 1.12-2.24 kg/ha applied 6-9 wk after planting provided statistically significant control of root rot in cotton. In an evaluation of basipetal translocation, about 0.25% of the radioactivity from 14C-labeled propiconazole applied to the leaves of cotton plants accumulated in the roots.