If you have a Hoelon-resistant ryegrass field or just a ryegrass field in general that will not be planted to wheat this fall, use a till-and-smooth fallow program on it this fall and next spring. This will encourage germination and deplete the soil of much of the ryegrass seed back.
In this year's wheat crop, do everything possible from a cultural practice standpoint to give the wheat a competitive edge, including optimizing variety selection, stands, planting dates and soil fertility. County Extension agents and wheat agronomists can help you there.
As I wrote in the previous article, once you have done as much as you can with cultural practices, you have to do the rest with herbicides. If your ryegrass infestation is Hoelon-susceptible, then Hoelon or Achieve will each work fine.
Finesse is the herbicide many farmers have used to control resistant ryegrass. Averaged over all of our work at the University of Arkansas, it has provided around 70 percent control. That is a long way from 100 percent, but we have combined it with good cultural practices, we have grown wheat without yield loss in heavy infestations of resistant ryegrass.
Finesse is used as a pre-emergence treatment at planting. Like any soil-applied treatment, it requires rainfall for activation.
Following an application of Finesse, the field can be double cropped only if an STS soybean variety is planted.
If you can destroy one heavy flush of ryegrass prior to planting, it will often greatly reduce the population that emerges in the crop.
When most growers get their final seedbeds prepared, they are going to plant. However, it really helps if you can get a nice, smooth seedbed prepared early, get a good flush of ryegrass up on it to destroy, and still have time to plant.
If you plant wheat no-till or stale-seedbed, be sure to use a burndown herbicide. Gramoxone or Roundup (or equivalent) will control emerged seedling ryegrass. Gramoxone tends to be better on wild garlic and also gives a much faster burndown of most weeds present.
This is not a place to cut the rates. Make sure you give wheat the chance to emerge in a completely clean seedbed.
Finesse is not recommended if wheat is broadcast-seeded.
In no-till wheat, Finesse can be tank-mixed with the burndown treatment and applied immediately after planting.
An alternative to Finesse that would not have any plant-back restrictions is two applications of Sencor. Not many farmers will want to make two treatments, but it has worked surprisingly well in our plots.
We are applying Sencor at the rate of 3 ounces per acre as quickly as wheat gets two leaves and a 1-inch secondary root. We then follow with a labeled rate for the soil texture as soon as the wheat reaches Growth Stage 3 (three tillers and four secondary roots).
Select a variety with outstanding Sencor tolerance. Our agronomists have a very active program that identifies these, and our county agents have the information.
Ford Baldwin is an Arkansas Extension weed scientist. e-mail: [email protected]