OLCA Research

POSTEMERGENCE CONTROL OF CRABGRASS USING VARIOUS HERBICIDES ALONE AND IN VARIOUS COMBINATIONS, RATES, AND SURFACTANTS – 2008

Principal Investigators: Dr. John R. Street and Deborah D. Holdren
The Ohio State University
Department of Horticulture and Crop Science 2001 Fyffe Court
Columbus, Ohio 43210
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Email: This e-mail address is being protected from spam bots, you need JavaScript enabled to view it or phone 614 795 7086

Crabgrass (Digitaria spp.) continues to be the key target among annual grassy weeds in Ohio and the Midwest in spring and summer. The strategy for germinated and tillered crabgrass is defensive by use of postemergence herbicides. The arsenal of postemergence herbicides prior to 2008 included fenoxyprop p-ethyl (Acclaim Extra), Dithiopyr (Dimension), and quinclorac (Drive). Much research has been conducted with these latter three post herbicides at OSU and other universities. Much in turn is known about activity and efficacy of these herbicides for postemergence crabgrass control. Drive has been reported to have good post efficacy on crabgrass in the early and later stages of crabgrass development (i.e. 2-5 tiller stage??) Thus, lack of reliability in crabgrass control has been evident with all the latter post crabgrass herbicides at times. A new herbicide that was labeled in 2008 for postemergence crabgrass control is Mesotrione (Tenacity). It has been included in this testing.

Three postemergence crabgrass studies were conducted in the summer of 2008. The results of these studies are provided in the three attached reports titled:

1) “Effect of Various Postemergence Herbicides on Crabgrass (Digitaria spp) Control at Different Maturity Stages – 2008”

2) “Effect of Tenacity (Mesotrione) on Preemergence and Postemergence Efficacy of Crabgrass (Digitaria spp) at Various Rates, Maturity Stages, and Herbicide Combinations – 2008”

3) “Effect of Various Late Postemergence Herbicide Treatments on Crabgrass Control at 5 to 7 Tiller Stage and Beyond – 2008”

We again are requesting a grant/gift from OLCA in 2009 to assist in supporting our postemergence crabgrass control research.

The main objectives of our 2009 research are to:

 (1) evaluate quinclorac (XLR8) and other experimental post herbicide formulations for efficacy on crabgrass, (2) evaluate the newer quinclorac (Drive) combination products (like Quintet, etc) for postemergence crabgrass efficacy, (3) determine the efficacy of Mesotrione (Tenacity) alone and in various combinations with so-called synergistic herbicides and surfactants for enhanced efficacy at various crabgrass maturity stages, (4) evaluate the latter herbicide combinations and surfactants to potentially enhance the efficacy of Tenacity to a single rate, and (5) evaluate potential approaches (additives) to eliminate the bleaching and/or whitening effect of Tenacity.

Herbicide studies will be displayed at both the OSU Turfgrass Research Field Day and the OLCA Field Day in August and a final report in 2009/2010.

We want to thank OLCA for their kind support in 2008.

John R. Street                                 Deborah D. Holdren

Associate Professor                        Research Associate

The Ohio State University               The Ohio State University