P&PDL Picture of the Week for
March 9, 2009

Crabgrass Control: Apply Your Preemergent Herbicide Soon

Glenn Hardebeck, Turfgrass Research Agronomist, Purdue University

If your lawn was one of many with problematic patches of crabgrass last summer, now is the time to prevent a repeat of last year.  Now is the season for crabgrass prevention.  Crabgrass loves thin turf, sunny locations and hot spots next to sidewalks drives or southern facing slopes.  It is a warm season annual grass which means it must germinate from seed each spring.  Crabgrass thrives during the summer heat when our desirable grasses are having a tough time and then dies off with nightly frosts in the fall.

There are several different active ingredients that are very capable of preemergently controlling crabgrass.  Accurate and uniform application is much more important than product selection.  The fertilizer/herbicide combination must be applied uniformly across the treated area at the correct rate for reliable control.  Rain/irrigation will not move the product into “skips”.  Additionally, preemergent crabgrass applications must be made before the crabgrass germinates which is generally early April in southern Indiana to late April in Northern Indiana.  Early applications are as effective as those timed just ahead of crabgrass germination since the herbicides are primarily broken down by microbes which are not very active now due to cool soil temps.

So if you choose to hold the crabgrass in check, don’t procrastinate with the crabgrass preventer application this spring.

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Did you have crabgrass patches last summer?

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service