What is in this article?:
- Glyphosate-resistant Italian ryegrass.
- Early burndown applications.
- Control prior to planting corn.
- Italian ryegrass field day.
Mid-South corn growers are thinking about planting because planes flying burndown herbicide applications have been active in the Delta when the weather has been good during the past few weeks.
The burndown calls have also increased since the middle of January, and many of these questions have been about controlling glyphosate-resistant Italian ryegrass. Hopefully, this is a sign that more growers and consultants are aware of the severity of the ryegrass problem and are taking appropriate steps to manage it early, before it becomes too large to control.
Unfortunately, research plots cannot be sprayed with an airplane, and the weather in January delayed many of our treatments for glyphosate-resistant Italian ryegrass. We were able to spray a few treatments during the third week of January.
Based on research over the last two years at Stoneville, mid-January to mid-February is the optimum time to apply clethodim (Select Max or 2-pound generic formulation) for control of glyphosate-resistant Italian ryegrass.
Although these early burndown applications of clethodim generally work slowly (five to six weeks for optimum effect), making the application as early as possible has several benefits. Without fail, smaller weeds are easier to kill.
Today (Feb. 3), most of the Italian ryegrass I have seen in the Mississippi Delta is still at a manageable size. However, I drove through northeast Louisiana earlier this week, and the Italian ryegrass in that area seems to have already entered the period of rapid growth that occurs in this species when temperatures begin to increase in late-winter.
In addition to Italian ryegrass still being relatively small right now, the “spring flush” has yet to begin. Little to no Italian ryegrass has emerged since mid-December in our monitoring plots scattered across the Delta.
Attempting to control fall-emerged and spring-emerged Italian ryegrass with one postemergence herbicide application is usually unsuccessful due to poor spray coverage. The fall-emerged plants are larger and their leaves will intercept the herbicide before it reaches the smaller spring-emerged plants.