VIEW ARTICLE

Effect of Trifluralin on Inoculum Density and Spore Germination of Fusarium oxysporum f. sp. vasinfectum in Soil. Anna Tang, Graduate Research Assistant, Department of Botany and Plant Pathology, Auburn University Agricultural Experiment Station, Auburn, Alabama 36830; E. A. Curl(2), and R. Rodriguez-Kabana(3). (2)(3)Professor, and Assistant Professor, respectively, Department of Botany and Plant Pathology, Auburn University Agricultural Experiment Station, Auburn, Alabama 36830. Phytopathology 60:1082-1086. Accepted for publication 18 February 1970. DOI: 10.1094/Phyto-60-1082.

The herbicide trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) enhanced production of chlamydospores of Fusarium oxysporum f. sp. vasinfectum in sandy loam and clay soils when applied at concn in the range of 0.6-40 µg/g. Most spore production occurred in the range of 0.6-5.0 µg/g herbicide and was more pronounced in clay soil. Numbers generally declined with increasing concn of the compound in both soils. The effect of trifluralin on germination of chlamydospores in nonsterilized clay soil was similar to that for spore production. Percentage germination was highest at the lowest herbicide concn (2 µg/g), then decreased at higher levels. Populations of fungi, bacteria, and actinomycetes also were higher in trifluralin treatments of 2-10 µg/g than in 20- and 40-µg treatments or in herbicide-free soil. These results suggest the possibility of a relationship of trifluralin effect to inoculum density and disease potential.