Recently, at the Tri-County Small Grains Field day, Southern Farm Network’s Bob Midles spoke with Wesley Everman, Assistant Professor and Extension Weed Specialist with NC State University about resistant Italian ryegrass in small grains:
“We have done a few different studies on the ryegrass. We have started mapping and screening it for resistance to different post emergent herbicides. We are starting to find more cases of multiple resistance to the available modes of action so we are losing our post emergence options in wheat. We have started studies to look at residual herbicides applied at different times of the year and with that comes reliance on the weather.
We did a preliminary study with a tillage block and a no tillage block. We did the same pre emergence spike stage or post emergence treatments across both so we could see how tillage affected weed control. We had much better control in the tilled plots. Tilled plots, for our pre herbicides and many of the post herbicides we saw better control. One of the first assumptions is with the tilled ground we don’t have the residue tying up the herbicides and needing as much moisture to activate. When you have residue on the surface, you need a little more rainfall to wash it off and get it into the soil. In the tilled ground, its going straight to the soil and you need less moisture to get it into the soil to control weeds.
We had really good control early in the season. In the eastern part of the state we had good rainfall so we had good activation of our pre herbicides and timely application of our post in Nov and Dec. We had a lot of clean fields with out ryegrass. The cool weather in March seems to have brought on a flush of it.”
And for that second round of ryegrass in wheat that’s tillered, there’s not much to be done says Everman.