Herbicide mixtures to help slow resistance in three turfgrasses

Abstract Single active ingredient herbicides were screened for Poa annua control in mostly single replicate trials on 4–12 weeks, and established turf. The species tested were Lolium perenne L. (LP), Lolium arundinaceum (Schreb.) Darbysh. (LA), and a fine fescue blend of Festuca rubra L. and Festuca rubra subsp. commutate . Gaudin. Fl. Helv. (FF). With three exceptions, no significant differences in turf quality could be found between 25 treatments on seedling turf 4–12 weeks old and established turf. Only haloxyfop in fine fescue blend controlled P. annua selectively. Numerous mixtures controlled P. annua selectively in each turfgrass; L. perenne 22, fine fescue blend 17, L. arundinaceum 17. For each species, two consecutive mixtures can be chosen that do not apply the same mode of action twice, for example (LP) 3.5 then 15.4, (LA) 5.2 then 3.15, (FF) 5.2 then 3.15.