With the increased wheat acreage in Arkansas, there are a lot of questions about ryegrass control. If ryegrass is present and has not been sprayed, now is the time to do it. Once ryegrass gets past about the two-tiller stage it is more difficult to control.
The herbicide of choice now on ryegrass seems to be Osprey. It provides good control of both Hoelon-resistant and non-resistant ryegrass and will pick up a few other species such as annual bluegrass.
It is best to put it out with a warming trend forecast. The recommended rate is 4.75 ounces per acre. Follow the label for recommendations on adjuvants and fertilizer carriers.
I still get questions about Hoelon for ryegrass control. In my opinion, Hoelon is the best and most consistent ryegrass herbicide there is if you do not have a resistance problem. Unfortunately, about the only way to know if you have Hoelon resistance is to spray Hoelon to find out. That is not a real good option.
I sometimes recommend Hoelon where a farmer tells me the field has never been in wheat and has never had any Hoelon used. For the most part, the resistance problem is so widespread you can not be guessing whether or not you have a problem.
For that reason, Osprey usually winds up being the wise choice. Keep in mind, however, it likely will not take that many years before we start seeing resistance to Osprey as well. A good overall integrated approach to ryegrass resistance management needs to be implemented.
One of the most important things is tilling and smoothing fields in the fall in the years they are not planted to wheat. That will encourage germination and then you can kill several crops with tillage during the fall and early spring. There is an excellent research base for this program, and it will do wonders for your ryegrass management efforts.
Another thing that needs to be done in the wheat crop a little later on is to spray any marestail or horseweed with 2,4-D if the field is to be double-cropped to soybeans. Any marestail that we have now must be assumed to be glyphosate-resistant.
I don’t know how many calls I received last year after wheat was cut on how to kill the marestail before no-till planting soybeans. My answer of a disk was not real popular. A lot of the wheat will be double-cropped, most want to no-till and a lot of the fields will have marestail.
You often badly underestimate how much marestail is in the field until the wheat is cut and the marestail shoots up out of the stubble. You generally do not have time to spray glyphosate to see if it will work, so conventional tillage is the best option.
If, however, you properly utilize 2, 4-D in the wheat crop, you can often reduce the marestail problem to a manageable level for the soybean crop.
With the marestail problem the way it is and with other weeds such as cutleaf evening primrose often problems, the first early spring burndown herbicide for any of the spring-planted crops needs to include some 2,4-D or dicamba. This usually means a glyphosate plus 2,4-D or dicamba application in February to early March. This not only gets them under control but gives the 2,4-D or dicamba time to get gone before planting.
There are some other options. The weed scientists at the University of Arkansas have worked very hard on marestail resistance and have some excellent recommendations. Catch Ken Smith or Bob Scott in a meeting and follow their recommendations.
The critical window is late winter and very early spring. Don’t let the window of opportunity pass.