Ryegrass Management in Corn

DR. Larry Steckel

 JACKSON, TENNESSEE

 There were a number of reports of ryegrass escaping burndown in fields that either will soon be planted to corn or just had been planted to corn.  Thankfully this issue seems less of a problem than a year ago.  In most cases the ryegrass escaped glyphosate + dicamba early burndown.  Paraquat application has the best probability of controlling ryegrass that has escaped early burndown.Depending upon how stunted the ryegrass was from the first application a follow-up paraquat application applied about 10 days later may be required to achieve complete control. Unfortunately, this is not an option to control ryegrass in emerged corn.

 In emerged corn it is often very hard to get good control. The best case scenario is when the ryegrass in the field is susceptible to SU herbicides. Then Steadfast would have a good chance of controlling it.  A good estimate on if the ryegrass is susceptible to SU herbicides is if herbicides like Osprey or PowerFlex still controlled it in wheat. Often in Tennessee, though not always, those two herbicides are ineffective on ryegrass in wheat.

 If the ryegrass is resistant to SU herbicides then the best alternative would be a Liberty application in corn that is tolerant to that herbicide. The best chance for success with a Liberty application is to make it in the middle of a hot day. Adding glyphosate would likely improve control some.  Do not expect 100% control with this application.  Jason Bond, weed scientist at Mississippi State, has done extensive research on this weed for well over a decade.  His data would indicate that 65 to 70% control is about all one can expect from a Liberty application on ryegrass.∆

DR. LARRY STECKEL: University of Tennessee