2021 Aphid Efficacy Trial in Tall Fescue

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Aphid management in grass grown for seed production

Aphid flights occurring in spring & fall each year can infest newly planted grass seedlings and established fields. Winged forms colonize fields in irregular patterns, often according to prevailing wind direction and wind-blocking features along field margins. We recommend regular scouting in April-May. Inspect seedling grasses for aphid colonies by visual exams; installing water traps for winged adults in spring, fall; and using sweep net samples. Consult PNW Insect Pest Management Handbook for available chemical control options.


  • Treat if 10 aphids for every two- to six-leaf seedling.
  • Treat if 10–20 aphids per stem or head (from boot to heading stage).

Prevention and management

  • Consider beneficials (parasitic wasps, syrphid larvae (hoverflies), lacewing larvae, lady beetles) when deciding whether or not to apply an insecticide. Individual aphids that are parasitized appear brown to gold.
  • Removal of volunteer plants that may act as insect reservoirs when crop host is not present.
  • Avoid planting into the previously infested ground; allow two weeks before planting.
  • Aphid populations are susceptible to rainy, windy weather, and sudden cold. Unseasonal high temperatures from April through June can reduce aphid populations quite effectively.

2021 Aphid Efficacy Trial

This is the second year of field evaluation of Transform® WG insecticide at two rates 0.75 and 1.5 oz/acre vs potential competitors (e.g. Sivanto) for aphid management in grass grown for seed. Data collected during Spring 2020 indicated that both rates of Transform® WG insecticide rapidly knocked down the aphid populations with a consistent low aphid counts in treated plots for up to four weeks after application. Data collection during Spring 2021 is underway. Results will be available soon!


Spring 2021 Aphid Efficacy Trial in Tall Fescue.


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