- Resistant barnyardgrass major problem in Mid-South rice fields.
- Computer model shows how to address the weed.
- Yellow nutsedge work also ongoing.
COMPUTER MODELING done by weed researchers has shown the best way to tackle resistant barnyardgrass. ““We want to understand how to best protect technologies and herbicides within rice and other crops,” says Jason Norsworthy.
In other work, Norsworthy has been working with yellow nutsedge.
“Several years ago, we found the first herbicide-resistant yellow nutsedge in the world. It’s a perennial weed and perennial sedges seldom reproduce by seed and rarely evolve herbicide resistance.”
While there is a bit of seed production by yellow nutsedge, “Overall, it reproduces by sending out runner with tubers – sort of like a peanut – below ground.
“The resistant yellow nutsedge we have has a prolific growth rate. It far exceeds that of just standard nutsedge. It’s absolutely amazing in its ability to grow, spread, and produce rhizomes.”
The resistant yellow nutsedge is “completely nonresponsive” to ALS herbicides like halosulfuron. The Mid-South continues to see an increase in ALS resistance among sedges, as a whole. “We have rice flatsedge that is also ALS-resistant.”
Further, “we have some growers throughout the Mid-South that are growing what I call ‘California rice’ -- zero-grade continuous rice. Some of those operations now have a weed common to California: smallflower umbrella sedge. It’s an annual sedge and is also ALS-resistant.
“To put it mildly, we really have our work cut out with resistance.”