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.


An update on the Oregon Seed Council and the Western IPM Center-funded project to conduct an area-wide survey of commercial grass seed fields. Our goal is to determine what species of entomopathogenic or insect parasitic nematodes and or other beneficial microbes occur in grass seed production systems and if these organisms have the potential to become promising biological control agents against soil-dwelling insects -like sod webworm, billbugs, and cutworms.

The objectives of this project are to 1) conduct area-wide surveys in the commercial grass seed production systems to determine the occurrence and distribution of EPN species in western OR, 2) identify the isolated EPNs using molecular techniques and maintain lab cultures for infectivity tests), 3) to conduct infectivity trials using EPN species identified during the survey and comparing their efficacy to the commercially available EPN based products against sod webworm under laboratory conditions.

Watch a short YouTube video for the project activities

  • We collect soil samples (five random locations per site) from commercial field sites (18) on a biweekly basis
  • Soil baiting experiment setup includes using a subsample of field-collected soil and baiting with healthy wax moth larva. EPNs are commonly reared on wax moth larva to maintain EPN culture and mass-produce. Wax moth larvae were ordered from Bassett’s Cricket Ranch (Visalia, CA, USA) through Amazon.com
  • Incubation- One-week incubation under the dark condition at ~22°C
  • Recovery of wax moth larva and transfer to white traps. A white trap is a method of placing infected insects in a small Petri dish inside a bigger Petri dish with a film of water
  • White traps are then incubated at room temperature (~22°C) and observed daily
  • Data is being collected and will be disseminated soon.

A survey is designed to assess current knowledge of biocontrol agents and practices and to evaluate the most critical limitations and knowledge gaps for developing biocontrol strategies for grass seed systems

Western IPM Center-Biocontrol Survey Phase 1

Please help us fill out this survey to collect baseline data on the control methods currently used by grass seed growers to manage soil-borne insect pests; 2) assess the feasibility and ability to integrate biocontrol tactics into existing insect pest management practices. We will distribute two $25 gift cards as raffle prizes. We appreciate your participation in this study!

Please contact Dr. Navneet Kaur or Dr. Betsy Verhoeven if there is any question.

Pocket Guide to Grass Seed Pests and Beneficials

Using the guide

This pocket guide provides information on pests and beneficial organisms
found in grass seed production fields across the state of Oregon.
Pests are organized alphabetically within each category. The guide includes
common occurrences; where pests are found; arthropod pest status;
identification; biology; symptoms of damage; what you might mistake one for;
thresholds, if known; ways to monitor; prevention tools and management; and
a pest scouting calendar based on crop stage.

The current registered chemical management options can be found in the
PNW Insect Management Handbook, https://pnwhandbooks.org/insect