A new herbicide for controlling ryegrass in wheat was recently labeled. Axial herbicide from Syngenta recently received a Section 3 label.
Axial, which contains the active ingredient penoxaden, is from the same family of chemistry as Hoelon, but it has a slightly different chemical structure.
While it is in the same family or group of chemicals as Hoelon, Select, Poast Plus and others, the accase enzyme inhibitors in it is a den, while the others are sometimes called fops or dims (this refers to the last part of the chemical name; for example, Clincher herbicide is cyhalofop, a fop).
These chemicals are sometimes referred to as the graminicides.
Because penoxaden, or Axial, has a slightly different structure than Hoelon, it has performed fairly well on Hoelon-resistant ryegrass in our trials over the last few years. One would suspect that cross resistance might not take long to develop since these chemicals are very close in structure.
For now, however, it does appear to be an option for Hoelon-resistant ryegrass.
Axial has provided excellent control of non-resistant ryegrass, very similar to Hoelon or Osprey.
In Arkansas, Axial basically will be a ryegrass material only. It provides some suppression of cheat, but it has no broadleaf activity and does not control annual bluegrass (poa). Unlike Hoelon, you can tank-mix Axial with most broadleaf herbicides (one exception: you cannot tank-mix Axial with 2,4-D).
The labeled rate of Axial is 8.2 ounces per acre. It comes in 40-acre packages with an adjuvant included (Adigor at 9.6 ounces per acre). I have been told that the price will be comparable to Osprey, possibly slightly less expensive. Osprey, however, has a wider spectrum of activity.
Axial should be applied to actively growing ryegrass from one-leaf to three tillers in size. It can be safely applied to wheat from the two-leaf to pre-boot growth stages.
Like Hoelon and Osprey, Axial does not provide any residual ryegrass control, so timing can be critical for season-long control. In severe ryegrass infestations, it may be necessary to make both Axial and Osprey applications for season-long control.
Another option would be to use Finesse pre and follow that application with either Axial or Osprey later in the season. Keep in mind that only STS soybean can be grown following Finesse applications.
Most crops, including soybean, have a four-month rotational interval to Axial.
Bob Scott is the University of Arkansas Extension weed specialist. e-mail: email@example.com