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Is the Time Right for Preemergence Herbicides? USGA Northeast Region Update

Posted on April 7th, 2021

Applying preemergence products too early might not provide season-long control of crabgrass and goosegrass.

The recent warmup has superintendents wondering if the time is right to apply preemergence herbicides for crabgrass and goosegrass. Goosegrass, in particular, is a growing problem in the Northeast, moving beyond the rough and fairways onto tees and greens.

When difficult-to-control weeds start to invade valuable and highly sensitive areas like putting greens, judicious herbicide applications may be necessary. If the weed pressure is low enough, hand picking is the safest method of control. However, in some instances – regardless of the surface – pre and postemergence herbicides are necessary. From a management and financial perspective, preemergence applications are the safest and most effective method of weed control.

Early springs force earlier preemergence applications which might not provide season-long control. If possible, apply preemergence herbicides in two or three applications rather than one full-rate application. Goosegrass germinates after crabgrass. If you apply one full-rate application in early spring, there might not be enough of a barrier to control goosegrass.

Remember that germination is soil temperature dependent, not date dependent.

Goosegrass and crabgrass germinate when the temperature of the soil in the top 2 inches is between 63 and 65 degrees Fahrenheit. Field reports indicate that soil temperature in Virginia is in the low 50s, and a little cooler as you move north in the region. Depending on where you are, it could be appropriate to apply preemergence herbicides this week or next, or you may need to wait several more weeks.

Every superintendent wants to take active steps to provide the best possible conditions for their golfers, but at times patience is a virtue. Just because the weather is nice enough to play golf doesn’t mean that it is time for regular maintenance. Focus on wrapping up winter projects and preparing the course for the upcoming season. Continue waiting on weed control and monitor soil temperatures for another two to four weeks – and be ready to make the first application when the time is right.

Northeast Region Agronomists:

Adam Moeller, director, Green Section Education – amoeller@usga.org

Darin Bevard, director, Championship Agronomy – dbevard@usga.org

Elliott Dowling, agronomist – edowling@usga.org

John Daniels, agronomist – jdaniels@usga.org

Information on the USGA’s Course Consulting Service

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