C A L I F O R N I A
FieldCrops A SPECIAL GROWERS’ REPORT OF AG ALERT ®
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Keeping rice fields weed-free can be a challenge. University of California farm advisors have been working to identify an unknown watergrass species that first appeared in 2017, as well as to keep known weed species at bay. But they say four new potential products for weed control in rice are undergoing testing, and could reach market soon.
Farm advisors report on rice weed control options ByBob Johnson
“FieldratesofCerano, Butte,GraniteGRandBolerowereusedas theearly-seasongran- ular applications. Field rates of SuperWham, Regiment andClincherwereused to test for the late-seasoncleanupapplications,” she said, adding that noneof thesewidelyusedma- terials showedtheability tocontrol thenewwatergrassweedonce it grewtomoderatesize. Brim-Deforest said she is updating her research results on the newweed pest on the Sutter-Yuba rice blog, ucanr.edu/sites/sutteryuba/Rice_Program_33. As newweed problems emerge and old ones spread, UC specialists said rice farmers should benefit fromnewmaterials that are about to be registered. “We are excited to see four new options for weed control being tested for rice,” said KassimAl-Khatib, UCCE weed specialist. “We are pretty excited that four molecules we have beenworkingwith since 2015 are coming tomarket soon.” Loyant, Pyraclonil, FMC, andoxyfluorofenonherbicide-tolerant Roxy riceareall likely to be registered in the next four years, Al-Khatib said. Recent trialsof the first inline for registrationamong thesenewmaterials suggest it could play aweed control role in either water-seeded or drill-seeded rice. “Ourmain question is: Could Loyant be used in the drill-seeded systems we use in the delta?” saidMichelle Leinfelder-Miles, aUCCE farmadvisor based in Stockton.
Rice farmers face aweed control roller coaster: Althoughmore than the usual number of newmaterials are coming to market to helpmanage resistance, troublesome weeds continue to spread and newones are being discovered. For example, a new watergrass weed has appeared in Sacramento Valley rice fields. Researchers are still working to identify theweed and come upwith a plan tomanage it. “In 2017, we had two fields with unknown watergrass species,” said Whitney Brim- Deforest, University of California Cooperative Extension rice andwild rice farmadvisor. “It doesn’t seem to respond to any of our herbicides very well. We are trying to identify it and screening herbicides.” Brim-Deforest made her remarks as rice researchers discussed emerging weed chal- lenges, and the possibility of new tools for managing them, during the 2021Winter Rice GrowerMeetingwebinar. “In 2017, I started getting reports of a watergrass biotype/species that was difficult to control using our suite of herbicides registered in rice,” she said. “In 2018, we collected eight samples fromthe field, andusedtwo latewatergrass samples fromknownsusceptible populations as controls.” Brim-Deforest said researchers conducted a screening in a greenhouse, “to see if we could replicatewhat wewere seeing in the field.”
See RICE, Page 8
April 21, 2021 Ag Alert 7
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