Insecticide Control of Thrips on Seedling Field Corn, 2019

摘要

Thrips feed on seedling field corn and usually do not require control,but sometimes can cause noticeably severe leaf injury. A trialevaluating foliar-applied insecticides was conducted at the Universityof Georgia Southwest Research and Education Center (32.0394,?84.3670) located near Plains, GA. A non-Bt, glyphosate-resistantcorn hybrid was planted on 1 May on 36 inch rows at the rate of34,000 seed per acre. Treatments were arranged in an RCB designwith four replications; individual plot size was 6 rows by 25 ftlong. Insecticide treatments were applied on 15 May at the 1 leafstage with a CO2-powered backpack sprayer equipped with TeeJet8002 flat-fan nozzles applying 15 gpa at 40 psi. Induce adjuvantat 0.5% v/v was added to all treatments. Thrips were sampled byplacing above-ground plants in 70% ethanol for 1–2 min to dislodgethrips. Samples were taken at 0, 2, and 7 DAT with 10 plantsper plot sampled at 0 DAT and 15 plants per plot sampled at 2and 7 DAT. Plant thrips injury was rated using the 0–9 scale, where0 = no injury and 9 ≥ 85% or more chlorosis at 14 DAT. The twocenter rows were harvested on 13 Sep with a plot combine equippedwith a system that measures grain weight, test weight, and moisturecontent. Grain yields were calculated and adjusted to a standard14% moisture content. Rainfall total from planting until spray applicationwas 1.5 inches, but only 0.09 inches fell during the sampleperiod. Plots were irrigated twice a week at 0.75 inch per irrigation.Data were analyzed by sample date using generalized linear mixedmodel analyses (PROC MIXED, SAS Institute 2016) with treatmentmodeled as a fixed effect and replication modeled as a random effect.When analyses suggested differences among treatments (α = 0.05),treatments were separated using the LS means separated PLM optionin SAS.