Crabgrass is a summer annual weed that germinates in lawns each spring (click here for crabgrass identification information). Preemergence herbicides prevent emergence of crabgrass plants from the soil. These products must be applied prior to crabgrass germination which could occur as early as April 1 in southern Indiana and three or more weeks later in northern Indiana in an average year (there don’t seem to be many average years these days). Purdue research has shown that these herbicides can be applied in late winter (February or later) and still be effective all season. It is essential to apply these products early in spring prior to crabgrass germination or they will not be effective and you’ll have crabgrass.
Often, preemergence herbicides are combined with fertilizers. Since fertilization should be minimized in the spring, purchase products with most of the nitrogen in slow release forms such as methylene ureas or sulfur or polymer coated ureas. Avoid products with mostly (>70% of total nitrogen) quick-release nitrogen such as urea or ammonical nitrogen. For more information on fertilizing your lawn, see Fertilizing Established Cool-season Lawns.
Do not use preemergence herbicides on newly seeded lawns or before seeding your lawn – except products that contain siduron (see below images). To be most effective, preemergence herbicides need to be watered-in after application which usually means rainfall in the spring since most irrigation systems aren’t yet operational. Refer to the label for specific instructions for each product.
Common Names (Ingredients) of Preemergence Herbicide Ingredients for Home Lawns
- Benefin/Trifluralin
- Pendimethalin
- Dithiopyr – product of choice if you wait to apply until after crabgrass germinates
- Prodiamine
I listed several ingredients above as our research has shown that all of these ingredients provide similar and effective crabgrass control in Indiana and the greater Midwest.
By maintaining a dense lawn, you can limit the amount of crabgrass. Proper fertility, mowing, and irrigation is essential for crabgrass control; consider herbicidal control only if necessary.
For more information on crabgrass germination and preemergence crabgrass control, see this posting (Common Questions About Crabgrass Germination and Preemergence Herbicides Answered) with multiple articles on this topic linked.
Here are some examples of products that you might encounter at your local store that will work well as a preemergence herbicide to prevent crabgrass emergence. For each I show the picture of the product as well as the “zoomed” in image showing you the ingredient in each.
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| Close-up of above picture. Same ingredient as the professional product Barricade. |
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| No fertilizer in this product, just the herbicide on an inert carrier. |
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| Close-up of above picture. Same ingredient as the professional product Pendulum. |
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| Similar to Halts Crabgrass Preventer but with the fertilizer (Turf Builder). |
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| Close-up of above picture. Same ingredient as the professional product Pendulum. |
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| Close-up of above picture. Same ingredient as the professional product Pendulum. |
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| Close-up of above picture. Same ingredient as the professional product Dimension. Useful ingredient if you apply after crabgrass germination as it will control crabgrass prior to tillering. |
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| Only preemergence products with siduron are safe to use in the spring when seeding cool-season turf. |
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| The ingredient in this product is siduron which allows cool-season grasses to germinate but prevents crabgrass from emerging. It is good for seeding but doesn’t last as long as other preemergence herbicides so it is not a good season-long preemergence herbicide. This ingredient is sold as Tupersan in the professional market. |
Aaron Patton, Turfgrass Extension Specialist