Evaluation of agronomic practices to reduce Russian wheat aphid, Diuraphis noxia (Mordvilko) (Homoptera: Aphididae), damage in wheat

The effects of seeding dates and insecticide application techniques on Russian wheat aphid Diuraphis noxia (Mordvilko) in winter and spring wheat Triticum aestivum was evaluated in 1988-1990.Autumn infestations declined with later seeding at each location.Winter wheat yields in untreated plots were not adversely affected by infestation levels of 18, 27 and 40%.Infestation levels were low at the 1-2 leaf growth stage?this stage is critical for damage to occur in the autumn.Winter wheat seeded in late September or early October showed reduced yields.Insecticide efficacy was enhanced by application technique.Granular insecticides applied in-furrow showed excellent control during the autumn growing period.However, reduced standcounts were observed with in-furrow applied organophosphates.Chlorpyrifos, applied as a spray, controlled an established RWA infestation.In general spring wheat seeded in early to mid April avoided infestations.Spring wheat yields were increased with the earlier seeding dates.Spring applied insecticide treatments did not effectively control infestation levels during the growing season.Granular insecticides applied in-furrow did not prevent late RWA (winged adults) from developing colonies on wheat plants.Chlorpyrifos lowered aphid numbers (90%) after application, however numbers quickly rebounded.