MASTER GARDENER — Turfgrass Management and Weed Control (Part 3 of 3)
Published 12:02 am Thursday, October 13, 2022
Gardeners, it seems fall is gentling rolling into our area this past week, as we have experienced moderate temperatures in the mid-80’s.
Hopefully each of you is seizing the opportunity to spend time outdoors, gardening of course. In last week’s segment (part 2), I detailed how to control weeds utilizing pre- and post-emergent herbicides, herbicide classifications, like whether it is a contact, systemic, selective or non-selective herbicide, and included specific weeds each type of herbicide acts upon.
It is a difficult topic but necessary for effective weed control. Before beginning the final installment, let me reiterate to always read and follow the directions before applying herbicides.
Please ensure the product you are planning to use will control specific weeds. Now let’s move on and discuss wintertime weeds, detailing what we should do now to “attack” them, mitigating unmanageable weed infested areas before spring arrives.
As our soil’s temperature cools, applying preemergent herbicides to eradicate cool season weeds like annual bluegrass and lawn burweed is now.
According to Chrissie Segars, Ph.D., AgriLife Extension turfgrass specialist in Dallas, “applying the correct preemergence herbicides now to lawns will disrupt the germination and emergence of unfavorable plants in the spring. Applying preemergent herbicides in the fall will help to rid your lawn of grassy weeds like annual bluegrass, rescue grass, broadleaf weeds like henbit, chickweed, Carolina geranium and lawn burweed (sticker plants).”
Weed identification is a critical step if you plan to control weeds utilizing herbicides, as it allows you to select the correct herbicide option, such as broadleaves, grasses, perennial or annual weeds.
Preemergent active ingredients are an important factor for tackling unwanted weeds and products always list a range of plants they control. Preemergent herbicides are most effective on annual weeds, while other weeds must be controlled with post-emergent applications.
Effective weed control and management begins with choosing the right active ingredient for your problem weeds and applying it correctly. I always recommend granular herbicides for homeowners due to ease of application.
Read and follow product label details thoroughly and follow distance applications from desirable plants which will avoid injuring them.
AgriLife Extension also recommends fall preemergent herbicide regimens, starting when soil temperatures reach 70 degrees.
As environmental conditions can be drastically different year to year, some weeds will germinate later in the season but applying products in a timely manner creates a preemergent program which stays ahead of weeds.
For best results, one application of a preemergent herbicide in the spring and fall, as these two applications, if done properly, will greatly reduce the number of annual weeds in your yard.
Herbicides are not 100 percent effective, especially if heavy rains follow the application or if you missed the desirable timing.
Utilizing a mixture of pre- and post-emergent products will catch “breakthrough” weeds of the original application while they are immature.
Water in the preemergent herbicide immediately after application using some type of sprinkler system is highly recommended, to activate the herbicide. Normally, granular preemergent products need ¼ to ½ -inch of water to dissolve properly. Waiting for rain can be risky!
“Weed and Feed” products
I’ve stated this before and I’m going to repeat myself: weed and feed products are very popular and many homeowners and gardeners use them (though not me), but I do NOT recommend using them as a fall or winter turfgrass management tool!
As we are entering a time when warm-season grasses are slowing down, let’s not fertilize them too late, especially with nitrogen fertilizer. Adding a nitrogen-based fertilizer now promotes growth, and freezing will cause substantial turfgrass damage.
The final nitrogen fertilizer application should be no later than six to eight weeks before the average first frost date, which for our area is typically mid-December but could occur as early as mid-November.
Approximately an inch of water per week is the summertime turfgrass irrigation recommendation for actively growing grass. Once fall temperatures arrive (now), fall rain should be enough.
Allowing grass to visibly wilt before application of supplemental water is a good rule of thumb. If we are receiving typical fall rain, you can turn the sprinkler system off or water as needed until the grass goes dormant.
Don’t overwater, but moisture in the soil is necessary until grass goes dormant, protecting it from winterkill.
Spring preemergent herbicide applications typically start when soil temperatures reach 50-60 degrees, for us it is typically somewhere between January to March. Identify the weeds you have and note their location, and create a “plan of attack” for getting your warm season turfgrasses off to a good start in spring.
Now my fellow gardeners, let’s go out and grow ourselves a greener, more sustainable world, one plant or lawn, at a time!
John Green is a Certified Texas Master Gardener. If you have gardening questions or need more information, contact the Orange County Master Gardeners Helpline at 409-882-7010 or visit txmg.org/orange, Orange County Texas Master Gardeners Association on Facebook or email firstname.lastname@example.org.