Effects of Herbicides on Endomycorrhizal Fungi in Florida Citrus (Citrus spp.) Soils

Abstract

Herbicide effects on vesicular-arbuscular mycorrhizal fungi were studied in greenhouse and field tests. In field plots treated with a bromacil (5-bromo-3-sec-butyl-6-methyluracil) and diuron (3-[3,4-dichlorophenyl]-1,1-dimethylurea) mixture, fungus infection was similar to levels present in cultivated plots. A slight reduction of infection occurred in roots of grove trees in a simazine (2-chloro-4,6-bis [ethylamino]-s-triazine) plus paraquat (1,1′-dimethyl-4,4′-bipyridinium ion)-treated plot compared to a cultivated plot. In the greenhouse studies, diuron, bromacil, and trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) had no apparent effect on Glomus etunicatus Becker and Gerd. and plant growth. Paraquat, PPG 844 {1-(carboethoxy) ethyl 5-[2′-chloro-4′-(trifluoromethyl) phenoxy]-2-nitrobenzoate} and simazine adversely affected plant growth and the fungus.