The clock is ticking for herbicide applications in winter wheat
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EmailEditor’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.
