Winter Weed Control Tips
Last week we talked about some key dates for treating lawn and landscapes with herbicides to achieve effective weed control. This is a follow-up to that discussion with some helpful details for the do-it-yourselfer. This also serves as a reminder to those who plan to hire lawn care professionals to treat their lawns. Contact them now so they can do the best possible job for you throughout the season.
If you are new to using weed control products, the discussion can get tedious and a bit confusing. Perhaps a few definitions would be helpful. These are simplified for the purpose of this discussion on winter weed control:
- Herbicide. A pesticide used to kill weeds.
- Pre-emergent. A herbicide that must be applied before the weed seeds germinate to be effective.
- Post-emergent. A herbicide that is applied to existing weeds.
- Grassy weeds. Plants with long thin leaves featuring parallel veins. Common examples are annual bluegrass and bromes. Vegetable gardeners should note that corn is also a grass.
- Broadleaf weeds. With only a few exceptions, any plant that is not a grass. Chickweed, henbit and shepherd’s purse are common examples.
- Winter weeds. These germinate in the fall, putting on little top growth but developing a root system in preparation for explosive spring growth. These are the weeds that can require frequent mowing before the turfgrass needs mowing, and then slowly dying away as the summer heats up.
- Warm season turfgrass. Primarily bermudagrass but buffalo and zoysia are also grown as lawns in our area.
- Cool season turfgrass. Primarily tall fescue but could also include perennial ryegrass and Kentucky blue grass.
Winter weeds can be controlled very effectively in the mid to late winter when the conditions are right. This includes adequate moisture so the weeds are not drought stressed, no chance of rain for the next 24 hours, temperatures of at least 50 degrees, sunny skies, and minimal wind. As you can see, this list of parameters eliminates most days in Oklahoma as “spray days”, so it is helpful to be ready and spray at the first available opportunity.
Herbicides choices are too numerous to list in this article but the key is understanding the majority typically control either grassy or broadleaf weeds, not both. See OSU publication #L441 Bermuda Lawn Management Calendar or OSU publication #L442 Cool Season Lawn Management Calendar for helpful information. Always read and understand the label for best results as well as protecting your personal safety.
One particular herbicide combination deserves special mention as it’s helpful for the most common lawn in our area, bermudagrass. Combining a 2,4-D based broadleaf product, a non-selective product containing the active ingredient glyphosate, and a pre-emergent crabgrass herbicide is an excellent way to get a jump on season long weed control. In situations where winter weed pressure is very high, this treatment can eliminate the need for 4 or 5 spring mowings. For homeowners looking to get their best “bang for the buck” with one treatment, this is it.
For more information on this or any other horticultural topic, you can contact Keith Reed, the Horticulturist in the Payne County Extension office. Keith can be reached via email at firstname.lastname@example.org, phone at 405-747-8320, or in person at the Payne County Extension office, located at 315 W. 6th in Stillwater.
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