I am writing about winter annual weed control again. However, if it doesn’t rain soon, we may not have to worry about any winter annuals germinating this fall. Winter annual weeds are weeds that germinate in the fall and complete their lifecycle in the spring. The completion is the formation of yellow and purple flowers or flowers and seeds with burs that cover lawns across Georgia. To reduce the need for late winter and early spring herbicide we need to plan our weed control program now.
Once your lawn has a purple shade to it form the henbit flowers it is too late to do much good. Controlling winter annual weeds early will reduce the amount of work you have to do later and reduce the seedbank for subsequent years. Although we have some really good herbicides, timing of application is critical for acceptable control without repeated and costly applications. Ask any farmer around here with a pigweed problem, and they will tell you that, “Timing is everything”!
Applying a herbicide or herbicides in the fall will help reduce or eliminate your need to do anything in the spring. There are several products that we can employ in this type of weed control strategy. For centipede and St. Augustine, we can use atrazine in the fall to control most of our problem weeds. The cautions for atrazine use are to not over apply and not apply during spring green up. For those with Bermudagrass, atrazine can be used once it is completely dormant.
For those of you with either Bermudagrass or zoysia you have some options as well. All of those products that are advertised for crabgrass control can be used to control several winter annuals. Products with active ingredients such as pendimethalin, oryzalin, and benefin are good products that will control annual bluegrass, chickweed and henbit. Dithiopyr, which is in Turf & Ornamental Weed & Grass Stopper, controls a few more weed species, but might be harder to find. For longer control a 2nd application may be necessary. These products will also work on centipede and St. Augustine.
I know how things go through; you get busy with fall and the holidays and next thing you know it’s January. By then these weeds are up and growing but doing so inconspicuously. It is not too late to do something about it. You can apply a 3-way herbicide mix and kill almost any broadleaf weed in the lawn. There are so many 3-way mixes I am not going to start and name them. The only thing you need to be careful with is using them near ornamentals and the rates on St. Augustine, and centipede. Centipede grass is sensitive to 2,4-D, St. Augustine is sensitive to dicamba and both products can injure ornamentals. If annual bluegrass is the problem, you’ll just have to call me. There are some products that will kill it once it is growing but they are not easy to find.
I hope this helps you prepare to deal with winter annual weeds and results in more time in spring for the important things like getting your pool clean or planting a garden. We’ll talk about that next year. contact your County Agent for more information on winter annual weed control.
