As summer heat creeps in, lawns are growing vigorously. The volume of calls I’m getting about lawns is growing too. After all, now is a time we pay them a lot of attention.
Lawn weeds are in a transition phase now. That is, winter weeds (like annual bluegrass and lawn burweed) are going to seed and dying out. Summer weeds like dollarweed, dichondra, and the infamous Virginia buttonweed are doing fine. If weeds are taking over an area, it may be best to kill everything with glyphosate (Roundup, Kills All, other brands). You may also have to spot-spray certain grassy weeds that selective herbicides don’t affect much.
For broadleaf weeds I advised people to use trimec-type herbicides last month. Now that the highs are 90 degrees or so, those herbicides come with a high risk of lawn damage. The only selective herbicides we can use now are MSM Turf and Celsius. Both are good at killing broadleaves without damage to the lawn. Another five degrees on the thermometer will render them dangerous as well. It’s best to apply them late in the evening to reduce risk.
Keep a healthy lawn (proper mowing height especially) to help the grass win its fight with weeds. But also be sure to apply herbicide if needed when the weeds are young. They’re more susceptible to chemicals and will not have taken over any large areas that way.
If you want to know more about gardening, landscaping, or anything else horticultural, contact the St. John & St. James Parishes Horticulture Extension Agent André Brock at firstname.lastname@example.org. Also, the LSU Ag Center’s website can be accessed at www.lsuagcenter.com with lots of user-friendly information, including this article.
The LSU AgCenter and the LSU College of Agriculture