EVALUATION OF SELECTED INSECTICIDES AND A TANK-MIXTURE FOR MANAGEMENT OF RICE STINK BUG AND REDUCTION OF PECKY RICE, 2002

Abstract

Rice stink bug (RSB) can be one of several contributing factors of rice grain discoloration, commonly referred to as Feeding RSB punctures developing kernels and allows the introduction of pathogens, which increases pecky rice. The efficacies of three insecticides were evaluated in rice to manage RSB populations and reduce incidence of pecky rice. In addition, fungicide azoxystrobin (Quadris 2.08SC, Syngenta) at 0.15 lb (AI)/acre was tank-mixed with an insecticide and evaluated for reductions of RSB infestation and the impact from pathogens associated with RSB damage. Rice was drill-seeded on 8 May in a Crowley silt loam at the Rice Research Station near Crowley, LA. Rice seed was treated with Icon 6.2FS at 0.044 lb (AI)/acre given a seeding rate of 90 lb/acre to control rice water weevils, Lissorhoptrus oryzophilus Kuschel. Plots consisted of 7 rows (8-inch centers and 20 ft in length). Plots were separated 10 ft from each other. Treatments were arranged in a RCB design with four replications. Plots were irrigated immediately after planting and then drained. Nitrogen was applied as urea at 160 lb N/acre prior to permanent flood on 30 May. Permanent flood was established on 31 May and maintained until 9 days before harvest. Insecticides and tank-mixture were applied using a back-pack sprayer pressurized with CO2 and calibrated to deliver 15 gpa at 20 psi equipped with a three-nozzle (1002VS flat fan) boom at 20-inch spacing. Monitoring for native infestations of RSB nymphs and adults started when rice reached 75% panicle emergence. Sampling was performed using a 15-inch diameter sweep net. Ten sweeps per plot were taken between 8 and 10 a.m. Clumps of newly emerged nymphs were counted as one individual RSB. Insecticide applications followed economic threshold levels, which are three RSB per 10 sweeps during the first 2 wk after panicle emergence and 10 RSB per 10 sweeps from 2 wk after panicle emergence until 2 wk before harvest. Treatments were applied by 10:30 a.m. on 31 Jul and on 6 Aug. A pre-treatment RSB sampling was conducted on 30 Jul. Post-treatment RSB populations were measured 1, 2, and 6 days after 1st treatment and 1, 2, 3, 6, and 7 days after 2nd treatment. RSB population density data were transformed [log (x + 1)] prior to ANOVA and LSD. Non-transformed means are presented in table. Plots were drained on 18 Aug and harvested at maturity on 27 Aug with a small plot combine. Yield data were adjusted to 12% moisture. Upon harvest, 2-lb grain samples from each plot were sent to Dr. David Black (Syngenta Crop Protection, Searcy AR) for analysis of % peck, grade, and milling quality.