Managing winter annual weeds early improves crop establishment and helps prevent yield losses in fall-seeded small grains.
Winter annual weeds can become a significant problem in fall-seeded small grains, competing with crops during the late fall and early spring. Common chickweed, henbit, marestail, and winter annual grasses can interfere with crop growth, potentially reducing yield if infestations are not controlled early.
According to Dwight Lingenfelter, Extension Associate in Weed Science with Penn State Extension, weed management should be based on the species present and their herbicide-resistance characteristics.
Harmony Extra and similar products remain important options for controlling broadleaf weeds in small grains. Field research has generally found fall applications to be more dependable than waiting until spring. However, growers should recognize that herbicide effectiveness can differ considerably among weed species and locations.
Common chickweed can often be managed with Harmony Extra or Quelex, although resistant populations are becoming more common.
In fields with ALS-resistant chickweed, growers may consider combinations involving Starane Ultra, Pixxaro, or metribuzin products such as Metricor. Treating chickweed during the fall can be particularly beneficial because larger plants may become harder to control later.
Marestail is generally easier to manage when plants are young. Herbicides containing 2,4-D or dicamba, along with products such as Huskie, Quelex, and Stinger, can provide control when plants are less than 4 inches tall.
Speedwell can present another challenge because some commonly used small-grain herbicides have limited activity against it. Depending on the species, combinations such as Harmony Extra with Quelex or Starane Ultra may improve control.
For winter annual grasses, products including Anthem Flex, Zidua, Osprey, and PowerFlex can offer control of brome species and annual ryegrass. Roughstalk bluegrass should also be addressed while plants are small, with fall or early spring applications generally preferred.
Application practices are equally important. Growers should follow product labels regarding adjuvants, spray timing, coverage, environmental conditions, crop rotation, and double-cropping restrictions.
Spray volumes of 15 to 20 gallons per acre may improve coverage, while cool temperatures, cloudy weather, wet foliage, or inactive weeds can reduce herbicide effectiveness.
Growers using frost-seeded or drilled companion crops such as red clover should also review herbicide recrop restrictions before applying treatments.
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