With rice acreage down this year, it presents an opportunity for growers to address weed issues, particularly weedy rice. University of California advisors are suggesting the fallowing of fields where there is weedy rice or other herbicide-resistant weed species. Rice Farm Advisor for Sutter, Yuba, Placer, and Sacramento counties, Whitney Brim-DeForest said it can very an effective method for cleaning up a field rapidly in one season.
“It’s not something I would say to do in every field obviously because it takes labor and time,” said Brim-DeForest. “But since we don’t have herbicides to control weedy rice, this would be a way to do it. Or again, we have a lot of herbicide-resistant weeds, specifically some of our watergrass species, this would be a good way to control those as well.”
There are two different approaches to fallowing that can help address weed issues. While lacking an abundance of research on the practice, dry fallowing is one option available to growers. Dry fallowing has the potential for increasing predation or the drying out of weedy rice seeds. For seeds that did receive some level of moisture and begin to grow, shallow tillage is recommended. A managed fallow on the other hand is a proven technique to eradicate weeds, however, it does require some level of irrigation.
“We would recommend that they do sort of a managed fallow where they’re flushing the field, waiting for the weeds to come up, and then once the soil dries, going out and doing a shallow tillage and then repeating the process,” Brim-DeForest noted. “If they are able to do it especially multiple times, it will have an effect.”
The lack of available water has significantly reduced rice plantings this year. With the reduction in acreage, there is ample opportunity to address weedy rice and other problematic weeds through fallowing. “We’re not sure the total loss in acreage but I think there’s an estimate of between 25 and 50 percent of the acreage being taken out this year. It kind of varies with location and what their water allocations are,” Brim-DeForest explained.