Weed Scouting in Mid-Winter

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Weeds can be a major pest of lawns and recreation fields, competing for resources and sunlight while detracting from their natural beauty.

If your spring checklist includes lawn weed management, now is the time to take a closer look at the tiny mat of weed seedlings forming in mid-winter (Jan-Feb.), especially during spells of mild weather and precipitation. The winter-weed inventory is likely to include a mix of early-stage cool-season annual and perennial weeds such as chickweed, henbit, clover, annual bluegrass, burweed, and wild garlic. One advantage of mid-winter weed scouting and management is that many weeds are in the early growth stages and can be effectively controlled by herbicide treatments. In addition, warm-season turfgrasses such as bermudagrass and zoysiagrass are dormant and less susceptible to herbicide injury than during spring green up. Mid-winter is an excellent time to scout for cool-season weed species and get an early jump on management while conditions are favorable.

Below are examples of lawn weeds commonly observed in mid-winter:
Pictured above: Henbit (left), Plantain (center), Tall Fescue in bermuda (right).

POSTEMERGENCE WEED CONTROL

Selective control of broadleaf and grassy weeds in turfgrass can be an effective strategy in mid-winter using the appropriate postemergence herbicide product(s). It should be noted that during the winter months the visible effects of certain herbicides may be masked by cool weather (the weeds may be dead and not know it yet!) Mature perennial weeds such as dandelion, clover, and undesired patches of tall fescue can be effectively spot-treated during mid-winter using selective and non-selective herbicides. It is essential to select products appropriate for the particular species or turfgrass when selecting herbicides. St. Augustinegrass and Centipedegrass are particularly susceptible to certain herbicide injuries, even during the winter months. Combination products containing fertilizer and herbicides may be appropriate for weed control in cool-season turfgrass species such as Tall Fescue during the late winter. However, combination products containing nitrogen fertilizer are NOT recommended for warm-season grasses during the winter months. Applying nitrogen to dormant warm-season grasses in mid-winter does not provide benefits to the turfgrass and promotes the development of diseases such as large patch.

Remember, turfgrass and weed identification is essential to determining the appropriate herbicide product, timing, and application rate. There are no miracle products or “one size fits all” solutions to weed control. Herbicide recommendations are based on many factors including the turfgrass species, weed species, temperature range, and environmental factors. For assistance with turfgrass and weed identification, contact your local UGA Extension Agent at 1-800-ASK-UGA1.

Download the 2017 Turfgrass Pest Control Recommendations for Professionals at www.GeorgiaTurf.com for the latest information on weed management, scheduling, and pesticide information.

References:

McCullough, Patrick E. PhD, Waltz, Clint PhD, (2015). UGA Extension Bulletin (C 978). “Weed Control in Home Lawns.”

Greg Huber
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