FENOXAPROP ACTIVITY INFLUENCED BY AUXIN-LIKE HERBICIDE APPLICATION TIMING

Fenoxaprop is used on turfgrasses to control smooth crabgrass [Digitar ia ischaemum (Schreb. ex Sweib.) Schreb. ex Muhl.] and other annual gr ass weeds. Our objective was to determine if a broadleaf weed herbicid e (BWH = 2,4-D + mecoprop + dicamba) would affect fenoxaprop activity. The BWH was applied several days or weeks before and after fenoxaprop was applied. Smooth crabgrass control by fenoxaprop was reduced signi ficantly when the BWH was applied less-than-or-equal-to 14 days before fenoxaprop was applied. Extremely poor crabgrass control occurred whe n fenoxaprop was tank-mixed with the BWH. There was no reduction in cr abgrass control when the BWH was applied 21 days before or greater-tha n-or-equal-to 3 days after fenoxaprop. Chemical names used: ethyl este r of [4-[(6-chloro-2-benzoxazolyl)oxy]phenoxy]propanoic acid (fenoxapr op); 2,4-dichlorophenoxy acetic acid (2,4-D); (+)-2-(4-chloro-2-methyl phenoxy)propanoic acid (mecoprop); 3,6-dichloro-2-methoxybenzoic acid (dicamba).