Apply fall preemergence herbicide to avoid spring weeds
As soil temperatures warm, now is the time to plan for preemergence herbicide applications to eradicate common warmseason weeds, said a Texas A&M AgriLife Extension Service expert.
Chrissie Segars, Ph.D., AgriLife Extension turfgrass specialist, Dallas, said homeowners looking to improve the look and feel of their lawns by preventing annual weeds and burs should prepare to apply fall preemergence herbicides. Preemergence herbicides are designed to disrupt the germination and emergence of unfavorable plants.
Ridding lawns of weeds Preemergence herbicide treatments in the spring broadleaf weeds like henbit and grassy weeds like sand burs. Choosing the right herbicide can seem daunting, but AgriLife Extension has a number of publications dedicated to identifying weeds and herbicide selection.
Products will typically list a range of plants it will control whether perennial or annual and broadleaf plants or grasses. Preemergence herbicides are most effective on annual weeds, while other weeds must be controlled with post-emergence applications.
Preemergence herbicide applications “Don’t get into the habit of relying on the same calendar date every year; that’s why we have soil temperature recommendations,” she said. “Environmental conditions can be drastically different from year to year. Some weeds will germinate later in the season but applying products in a timely manner builds up a preemergence program that stays ahead of weeds.”
Identifying which weeds you want to control is important for choosing the correct herbicide option, such as broadleaves and grasses or perennial and annual weeds, she said. Segars recommends granular herbicides for homeowners due to ease of application.
“For best results, we generally recommend at least one application of a preemergence herbicide in the spring and fall,” she said. “These two applications, if done properly, can greatly reduce the number of annual weeds in your yard.”
Segars said some homeowners may desire to make a second or split application of preemergence, and it’s a good idea to have both a pre- and post-emergence herbicide on hand for the second application.
“Herbicides aren’t 100% effective every time, especially if you have heavy rains following application or missed the desirable timing,” she said. “Having a mixture of a pre- and post-emergence product just ensures you catch any weeds that break through your original application while they are immature.”
Watering in the preemergence herbicide immediately after application using some type of sprinkler system is recommended. Typically, granular preemergence products need one-quarter to onehalf inch of water to dissolve properly, but always follow product label instructions, she advised.
Scout now for spring preemergence application Segars said now is a good time to scout for summer weeds like crabgrass and sandburs. Sandburs are a warmseason perennial grass known for their spiked seed pods that grow at the end of the stem and drop or attach themselves to any human or animal passersby.
Spring preemergence applications typically start when soil temperatures reach around 50-55 degrees, which can be January to March based on location and weather conditions.
“Make note of what weeds you have now, and prepare for spring preemergence application,” she said. “Identify the weeds you have and note where they are. Make a game plan for getting your warmseason grasses off to a good start in the spring.”