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Make weed control plan part of wheat program

According to almost everyone I talk to, wheat acreage will be up across the Mid-South this fall. In Arkansas, we will be coming back from wheat acreage as low as some people can remember.

I hope many growers took the opportunity to break the cycle of ryegrass their fields while they were fallow or in other crops.

My research counterpart in Fayetteville, Dick Oliver, has shown over the past few years that one year of fallow (and clean) in a continuous wheat program will result in as much as 80 or 90 percent ryegrass control in the following wheat crop. There are options, however, for farmers whose fields that will likely have ryegrass.

In our trials, Osprey — applied at 4.75 ounces per acre with both a 0.5 percent nonionic surfactant and 1.5 pints per acre of 32 percent nitrogen or 1 percent MSO as an adjuvant — has consistently provided over 90 percent control of both Hoelon-resistant and susceptible ryegrass.

The Osprey label includes a lower rate for wild oat control, but in our work 4.75 ounces was needed for consistent control of ryegrass.

Osprey performed well in the field last year. Most growers and consultants liked the flexibility of being able to add a broadleaf herbicide. Osprey's lack of residual control of ryegrass can be a problem applied too early.

In addition to ryegrass, Osprey will suppress or control many broadleaf weeds, including vetch, shepherdspurse, mustards, henbit and buttercup. It is an excellent wild oat material. There are few rotational restrictions to Osprey, and for all intents and purposes it should be considered a material with post activity only.

In circumstances where a fall application is missed, Osprey can be applied until just prior to wheat jointing. Salvage ryegrass applications are labeled, but I recommend you get it under control before then.

In those fields that have both Hoelon-resistant ryegrass and wild garlic, it will probably be necessary to make two applications, one for ryegrass in the fall and one for garlic in the spring, because the treatment windows do not match up well.

Finesse herbicide has been an option in Arkansas for Hoelon-resistant ryegrass control, but rotational crops are a serious concern. You must follow Finesse-treated wheat with STS soybeans.

Another problem with using Finesse is that it is applied pre-emergence and requires immediate rainfall for good activity on ryegrass. When rainfall occurs, control of ryegrass is excellent with Finesse. When rainfall is delayed, ryegrass control is inadequate.

It is my understanding that the cost of 4.75 ounces per acre of Osprey will be set similar to 1.33 pints of Hoelon. The cost of Finesse is significantly less. One option on Hoelon-resistant acres would be to use Finesse and see if you get a rain before you automatically invest in Osprey.

Due to Osprey's lack of residual, Hoelon is probably still the best option for ryegrass control if the ryegrass is not resistant. Of course, you may want to consider a rotation to Osprey or Finesse if you have used Hoelon for several years in a row to prevent the buildup of Hoelon-resistant ryegrass on your farm.

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