Rice Water Weevil Control, 1990

The objective of the experiment was to compare RWW control among insecticide treatments. The test was performed at the California Rice Experiment Station, Biggs, in 1990 using a RCBD with 4 replications of 2 insecticide treatments and an untreated control. Treatments were applied to 0.94-m diam circular plots, each bounded by a 0.7-m tall aluminum sheet pushed 3-4 cm into the soil. Plots were established on Stockton adobe clay soil and were water-seeded at a rate of 140 kg/ha on 4 May. Stands were thinned to 50 plants per ring on 25 May. Water depth in the plots was maintained at 10 cm during the experiment. Furadan 5G was applied with a hand-held granule shaker 2 d before flooding and seeding of plots and lightly incorporated by rake into the soil. NTN 33893 240 FS was applied to seeds at a rate of 187 kg per 100 kg seed by the manufacturer before planting. Rings were open on top, allowing for natural ingress of adult RWW into the plots. Twenty-five fieldcollected parthenogenic adult RWW per ring were added on 23 May. The 2 youngest, unfurled leaves on each of 20 plants per plot were examined on 23 May (before artificial infestation), 30 May, and 5 Jun for scarring caused by adult RWW feeding. Ten, 10-cm diam soil cores per plot (1 plant per core) were removed on 22-25 Jun (1 replication per d). Soil was washed from the roots and the number of immature RWW (larvae plus pupae) per core was recorded.