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crab-pre application #927972

Asked April 10, 2026, 8:24 AM EDT

how long granuler crab-pre stays in soil in first couple inches

Livingston County Michigan

Expert Response


Hi, thanks for using Ask Extension.

For the most part, the effective active period for pre-emergents used on crabgrass is roughly 8 to 12 weeks in the upper layer of soil. These pre‑emergent products remain in the top 1–2 inches of soil because the active ingredients bind tightly to soil particles and do not move downward with rainfall.  Prodiamine is one of the longest‑lasting pre‑emergents  and does not dissolve well in water, stays near the soil surface, and has a soil half‑life of about 69 days.  Warmer temperatures, moisture, and microbial activity gradually break the product down, but under typical spring conditions it provides a stable barrier in the first couple inches of soil.

  • Prodiamine 8–12 weeks
  • Dithiopyr 8–10 weeks
  • Pendimethalin 6–8 weeks
  • Corn Gluten Meal 2-4 weeks

http://npic.orst.edu/factsheets/prodiamine.html

http://npic.orst.edu/factsheets/pendtech.html

http://npic.orst.edu/factsheets/dithiopyr.html

https://hortnews.extension.iastate.edu/1999/4-23-1999/cornmeal.html

I hope this is helpful.

An Ask Extension Expert Replied April 10, 2026, 7:27 PM EDT

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