The clock is ticking for herbicide applications in winter wheat
Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.
Of all the crops grown in Michigan, winter wheat has typically been the
crop that has not been intensively managed. However with higher wheat
prices, growers are looking at more intensive management to maximize
yield. Where weeds are present, herbicide applications to control both
winter and summer annuals is one management practice that may improve
yield at the end of the season.
There are several different herbicides that growers can use for weed control in winter wheat. However, not all of these herbicides have the same weed control spectrum or application timing. As growers look for weed control options, they need to keep in mind that herbicide choices need to be based on what weeds are in the field and more importantly the stage of wheat growth. Late herbicide applications can lead to excessive herbicide injury that can cause kernel abortion and blank wheat heads, ultimately reducing yield. Plant growth regulator herbicides including 2,4-D amine and ester, dicamba (Banvel or Clarity), MCPA and Curtail (2,4-D amine + Stinger) all need to be applied prior to winter wheat jointing (Feeke’s stage 6). These herbicides are typically good on summer annual weeds like common lambsquarters, pigweed and common ragweed, but vary in their control of some of the more common winter annual weeds like common chickweed. 2,4-D, MCPA and Curtail will not control chickweed. With the warmer weather conditions, it is important to scout fields and make sure wheat has not exceeded the maximum growth stages in which these herbicides may be applied.
Herbicides including Affinity BroadSpec, Harmony Extra, Harmony and Express do not have the same restrictions as many of the plant growth regulator herbicides. These herbicides can be applied when the wheat is at the 2-leaf stage (Feeke’s stage 1.2) to just before the flag-leaf is visible (Feeke’s stage 7.9). All of these herbicides also have better control of common chickweed than many of the growth regulator herbicides. Peak, another herbicide, is also an option for common chickweed control, however longer rotation restrictions (22-months) on many crops including soybean often restrict the use of this herbicide.
Buctril, Stinger, Starane and Widematch (Stinger + Starane) are other herbicides that will control broadleaf weeds in winter wheat. These herbicides have the longest application window. They can all be applied to winter wheat up to the boot stage (Feeke’s stage 9). However, many of these herbicides have fairly narrow spectrums of weed control. Buctril provides better control of summer annual weeds and is not very effective against winter annuals. Starane has a very narrow weed control spectrum, but is excellent in controlling hemp dogbane. Stinger, on the other hand, provides excellent Canada thistle control.