Thursday, July 31, 2014

Postemergence Crabgrass Control

Dr. Kevin W. Frank and Aaron Hathaway
Michigan State University

It seems like every year is now a crabgrass year and this year is no different.  Even though summer temperatures have been less than stressful to this point in the summer frequent rainfall has kept the turfgrass and the crabgrass growing.  The best defense against crabgrass invasion is maintaining a healthy, dense turf stand by mowing high and fertilizing throughout the season.  If postemergence crabgrass control is in your future here’s a quick herbicide primer.       

Postemergence Control

Postemergence control is generally more effective when crabgrass is younger before it has tillered.  As crabgrass matures, postemergence control becomes more challenging and multiple applications spaced 2-3 weeks apart are necessary to achieve control. 
Crabgrass enjoying the summer next to a sidewalk.

MSMA is no longer available for selective grassy weed control in lawns/commercial turf.   MSMA can be used on golf courses and sod farms.  There are several options for controlling crabgrass in cool season turf: Drive (active ingredient (a.i.) quinclorac)), Acclaim Extra (a.i. fenoxaprop-ethyl), Tenacity (a.i. mesotrione), and Pylex (a.i. topramezone) are all effective for postemergence control.  For homeowners the primary herbicide you will find on the shelf at your favorite store for postemergence crabgrass control will contain quinclorac. 

Quinclorac provides excellent control of crabgrass at almost any growth stage (seedling or mature) and is very safe when applied to new seedings.  Quinclorac, mesotrione, and topramezone also have the added benefit of providing control of some broadleaves such as white clover and dandelion.  Fenoxaprop-ethyl is generally not as effective on larger or more mature crabgrass as quinclorac, but can provide excellent control of other grassy weeds, such as goosegrass, that are not effectively controlled by quinclorac.  Topramezone also provides control of goosegrass.

Always read, understand, and follow the label directions. Mention or exclusion of specific products does not represent an endorsement or condemnation of any product by Michigan State University. 

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