It is not too late to take care of some troublesome weeds in wheat.
One problem with spraying this time of year is temperature. When it gets cold, many enzyme-inhibiting herbicides, like Osprey, do not work as well.
It has to do with that statement on many herbicide labels that reads, “Spray to actively growing weeds.” Below 45 or 50 degrees, even most winter wheat weeds are not actively growing. So, control may not be as good as it would be if temperatures were above 55 degrees for two or three days before and after application.
In some cases, it may be better to delay applications. With Osprey, this can be difficult because of a statement on the label that says injury may occur if nitrogen fertilizer is applied too close to an Osprey application (the most recent label I could find said within 14 days).
Try to make sure fertilizer activation with rainfall does not come at the exact time of an Osprey application and you should be ok.
Also, you do need to use an MSO at 1 percent v/v with Osprey. Crop oils have been shown to not work as well.
Osprey at the full rate is still very active on larger ryegrass and does a fair job on bluegrass, many broadleaves and vetch in late January and early February. It can be tank-mixed with Harmony Extra for garlic, but stay away from tank-mixes with 2,4-D, dicamba or Sencor.
If you do not believe you have Hoelon-resistant ryegrass, then Axial or Hoelon is a good option for spring ryegrass control. You will need the full labeled rate of either herbicide for best results.
Do not tank-mix broadleaf materials with Hoelon. As for the Axial, some broadleaf tank-mixes are allowed. We have not had a good look at these, so my best advice on that is to follow the label.
If you are planning to grow soybeans behind wheat (looking at soybean futures, I bet many of you are), do not miss a chance to kill horseweed in the wheat crop prior to joint elongation. Harmony Extra (0.5 ounce per acre) plus 1 to 1.5 pints per acre of 2,4-D is great.
For really heavy infestations add 4 ounces per acre of dicamba to the mix. This will typically kill young horseweed. There can be some slight damage to wheat with this or any 2,4-D application to wheat, but as long as it is prior to joint movement, the wheat should be fine.
This treatment will also control mayweed, vetch, mustards, garlic and many other broadleaf weeds. Again, do this for your soybean crop as much as your wheat. It will be much easier to treat the horseweed in wheat than to deal with glyphosate-resistant horseweed in-season or preplant in soybeans, where options are limited.
Many broadleaf weeds are not that damaging to wheat yields at the end of the year. Chickweed, henbit, shepherd’s purse, and many mustards simply do not compete well with an annual grass crop like wheat.
Mayweed, plains coreopsis and buttercup are slightly more competitive and almost always should most be controlled.
Wild buckwheat and vetch are vines and will cause major harvest problems.
The garlic and onion complex cause contamination of harvested grain and should be controlled. Harmony Extra at 0.5 ounce per acre is the industry standard for garlic and onion and many of other broadleaves.
2,4-D is cheap and will do a fair job on garlic/onion. Peak is also an excellent late spring garlic control herbicide, although it has crop rotational issues with soybeans.
Annual bluegrass is usually not that competitive with wheat either. In terms of yield, adding 5 or 10 extra units of nitrogen will do about what controlling bluegrass will do.
Osprey is the best thing I can recommend this time of year for bluegrass control if you want to get rid of as much as possible. Earlier in the season I would have recommended Sencor.
Some varieties are not tolerant to Sencor. For some time we have not had a good list of Sencor-tolerant varieties. We have resurrected the Sencor tolerance screening and I should have a partial list started in time for next fall.