When to control winter annuals and perennial broadleaf weeds in turf

Many weeds are currently flowering in turf and lawns, but not all require control.

Despite the seasonable temperatures we’ve recently felt in April, the summer in March continues to accelerate the phenological calendar for weeds flowering in turf. Whereas May is usually the time to focus on dandelions, this year it’s April. In most areas, the first flush of dandelion color has come and gone and now the puff ball stage is in full effect. If you’re looking to control dandelions in the spring, now is the time to take your shot.

There are numerous other weeds flowering in the turf right now including common chickweed, henbit, shepherd's purse, yellow rocket, corn speedwell, wild violet, and ground ivy. Not all of these weeds require you to take action to try and eliminate them. All but wild violet and ground ivy are winter annuals. If you don’t understand the life cycle of a winter annual, you might be tempted to try and kill them with a herbicide. The life cycle of a winter annual is that they germinate in the fall, overwinter, and then flower and produce seed in the spring. After flowering in the spring, winter annuals are usually only two to three weeks from dying. So the classic saying, if you apply herbicide now they will be dead and gone in two to three weeks and if you do nothing they will be dead and gone in three weeks.

On the other hand, now is the second best time, behind fall, to control perennial broadleaf weeds that are flowering such as ground ivy and wild violet. If you have any questions about weed identification or recommendations to control weeds in turf areas, make sure to visit www.msuturfweeds.net.

Dr. Frank's work is funded in part by MSU's AgBioResearch.

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