Tadpole shrimp targeted in rice station research effort
ByBob Johnson Evenwhenmanaged before they dam- age the rice crop, tadpole shrimp can contribute to pesticide-resistance prob- lems that make other common rice pests more difficult to control. These critters feed on the roots of young rice and can uproot enough of the plants to prevent a good stand from get- ting started. “The standard treatment is Warrior, a pyrethroid, and resistance is a concern,” said Ian Grettenberger, University of California Cooperative Extension ento- mology specialist. Grettenberger and other researchers discussed insect pest management in rice at annual rice grower meetings in March. He is leading trials at the Rice Experiment Station in Biggs, searching for alternatives that may help growers manage pyrethroid resistance. Because shrimp eggs hatch shortly after contact with water, UC integrated pest management advisors suggest wa- ter seeding rice soon after flooding. This is so the pest does not have time to grow before the rice germinates. They also suggest flooding and drain- ing the field quickly to kill the recently hatched shrimp. Grettenberger saidDiamide, amaterial
that causes shrimp to release storedcalci- um, workedwell. He said biological con- trol, such as employing fish that eat the tadpole shrimp, also showed promise. “The higher the density of fish, the less damage we got,” he said. Warrior still workedwell in themost re- cent trials at the Rice Experiment Station, but Intrepid andDimlin applications did not, Grettenberger said. Although pyrethroids remain effective against tadpole shrimp, their widespread use for this purposemay bemaking them less effective against armyworms. “Repeated use of pyrethroids for tad- pole shrimp is driving resistance in ar- myworms,” said Luis Espino, UCCE rice farm advisor in the Sacramento Valley. Espino also monitors a network of traps and sends out regular email no- tices to help growers with another chal- lenge—populations of armyworms, whose larvae defoliate plants and may cause yield loss by causing panicles to dry before filling. Summer control of broadleaf weeds in the field can deprive armyworms of their preferred habitat for laying eggs. Growers can also use variety differ- ences to manage armyworms in heavily infested fields.
In test fields at the Rice Experiment Station in Biggs, above, researchers work on remedies to rice damage caused by tadpole shrimp, right.
A 50% defoliation level was enough to cause significant yield loss for M-206, a medium-grainCalrose rice, according to Espino. It took 75% defoliation to cause the same yield loss in another Calrose variety, M-205. One piece of good news is that rice water weevils, which can be particularly damaging economically, have recently been in decline. “We used to have more rice water weevils than we do now,” Grettenberger said. “The last couple years (the popu- lation) has been very low.”
The larvae can cause stunting, which results in reduced yields by pruning the roots of young rice plants. Damage is usually greatest near the edges of the field and can be reduced by goodweed control in areas near the field, according to theUCStatewide Integrated Pest Management Program. More information on tadpole shrimp managementmaybe foundat ipm.ucanr. edu/agriculture/rice/tadpole-shrimp. (Bob Johnson is a reporter in Monterey Coun t y . He may b e c on t a c t ed a t bjohn11135@gmail.com.)
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Quotations are the latest available for the week ending April 29, 2022 Year Ago Week Ago Latest Week Livestock Slaughter Steers – 5-Area Average Select & Choice, 1050–1150 lbs., $ per cwt. 120 139 140-141 Hogs – Average hog, 51-52% lean, Iowa-Minn. market, $ per cwt. 104.79 99.81 99.79 Slaughter Lambs – $ per cwt. 125–175 lbs. National weekly live sales 180-210 196-249.50 199-280 Field crops – basis prompt shipment Barley – U.S. No. 2, $ per cwt. Truck, Stockton-Modesto-Oakdale-Turlock 14 No Quote No Quote Cotton – ¢ per lb., Middling 1 3/32” Fresno spot market 79.49 98.04 99.65 Corn – U.S. No. 2 yellow $ per cwt. trucked 8.55 No Quote 9.90 Alfalfa Hay – $ per ton, quality*, FOB Region 1, Northern Inter-mountain No Quote 250 (F/G) No Quote Region 2, Sacramento Valley 280-300 (orchard mix) 360 (orchard mix) No Quote Region 3, Northern San Joaquin Valley 270-295 (P/S) 370-390 (P/S) No Quote Region 4, Central San Joaquin Valley 265-300 (P/S) No Quote No Quote Region 5, Southern California 259 (P) No Quote 19.50-21.50 (per bale) Region 6, Southeast Interior 220-225 (P/S) 365-380 (P/S) 363-390 (P/S) Oat Hay – $ per ton, quality*, FOB Northern California, dairy No Quote No Quote No Quote Oats – U.S. No. 2 white, $ per cwt. Statewide, trucked price No Quote No Quote No Quote
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Dry Beans – Grower FOB prices Baby Limas, $ per cwt, (sacked) Large Limas, $ per cwt. (sacked) Blackeye, $ per cwt. (sacked)
No Quote No Quote No Quote
No Quote No Quote No Quote
No Quote No Quote No Quote
Rice – Milled No. 1 Head, FOB No. Calif. mills Medium grain, $ per cwt. Wheat – U.S. No. 2 or better, winter, $ per cwt. 13% protein, Los Angeles, trucked price
39-43
54-56
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12.75 (No. 3) No Quote Provided by the California Farm Bureau as a service to Farm Bureau members. Information supplied by the U.S. Department of Agriculture’s Market News Branch. * ADF=Acid detergent fiber; (S) = Supreme/<27%ADF; (P) = Premium/27-29; (G) = Good/29-32; (F) = Fair/32-35. No Quote
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May 4, 2022 Ag Alert 11
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