Pacific Northwest Insect Management Handbook

Field and silage corn-Grasshopper

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Several species

Pest description and crop damage Have caused extensive defoliation during some years.

Management-chemical control

  • alpha-cypermethrin (Fastac CS) at 0.017 to 0.025 lb ai/a. REI 12 hr. PHI 30 days grain and stover; 60 days forage. Retreatment interval 3 days. Do not exceed 0.075 lb ai/a per season.
  • azadirachtin (Neemix 4.5)-PHI 0 days. REI 12 hr. See label for rates. Slow acting. Apply early. Thorough coverage and repeat applications are necessary. Some formulations are OMRI-listed for organic use.
  • beta-cyfluthrin (Baythroid XL) at 0.017 to 0.022 lb ai/a. PHI 0 days for green forage and 21 days for fodder or grain. REI 12 hr. Do not exceed 0.088 lb ai/a per season.
  • bifenthrin (Brigade 2EC) at 0.033 to 0.1 lb ai/a. PHI 30 days for harvest, grazing, or cutting for feed. REI 12 hr. Do not apply more than 0.3 lb ai/a per season.
  • bifenthrin/zeta-cypermethrin (Hero) at 0.025 to 0.06 lb ai/a. PHI 30 days grain and stover; 60 days forage. REI 12 hr. Do not graze for 30 days after treatment. Do not exceed 0.4 lb ai/a per season.
  • carbaryl (Sevin 5 Bait) at 2 lb ai/a. PHI 14 days for forage or silage or 48 days for grain or fodder. REI 24 hr. Do not exceed four applications per season. Retreatments every 14 days.
  • chlorantraniliprole (Coragen) at 0.026 to 0.065 lb ai/a. PHI 14 days. REI 4 hr. Do not exceed 4 treatments nor 0.2 lb ai/a per season. Retreatment interval 7 days.
  • chlorantraniliprole/lambda-cyhalothrin (Besiege) at 0.52 to 0.08 lb ai/a. PHI 21 days. REI 24 hr. Do not exceed 0.12 lb ai of lambda-cyhalothrin or 0.2 lb ai of chlorantraniliprole per acre per growing season. Retreatment interval 7 days.
  • cyfluthrin (Tombstone) at 0.033 to 0.044 lb ai/a. PHI 0 days for green forage and 21 days for grain or fodder. REI 12 hr. Retreatment interval 7 days. Do not exceed four applications or 0.175 lb ai/a per season.
  • deltamethrin (Delta Gold) at 0.012 to 0.018 lb ai/a. PHI 21 days for grain or fodder or 12 days for forage or grazing. REI 12 hr. Retreatment interval is 21 days. Do not exceed 0.095 lb ai/a per season. Limit 5 treatments per year.
  • dimethoate (Dimethoate 400) at 0.5 lb ai/a. PHI 14 days forage; 28 days grain. REI 48 hr. Do not exceed 0.5 lb ai/a per season.
  • esfenvalerate (Asana XL) at 0.03 to 0.05 lb ai/a. PHI 21 days. REI 12 hr. Do not exceed 0.25 lb ai/a per season.
  • gamma-cyhalothrin (Declare) at 0.01 to 0.015 lb ai/a. PHI 1 day for grazing and forage, or 21 days for fodder and silage. REI 24 hr. Do not exceed 0.06 lb ai/a per season.
  • indoxacarb (Steward EC) at 0.059 to 0.11 lb ai/a. PHI 14 days grain, 1 day forage, fodder, silage. REI 12 hr. Limit 2 treatments. Do not exceed 0.22 lb ai/a per year.
  • lambda-cyhalothrin (Warrior II) at 0.02 to 0.03 lb ai/a. PHI 21 days. REI 24 hr. Do not apply more than 0.12 lb ai/a per season, 0.06 lb ai/a after silk initiation, or 0.03 lb ai/a after milk stage.
  • malathion (Gowan Malathion 8, Fyfanon 8) at 0.6 to 1 lb ai/a. PHI 5 days. REI 12 hr. Limit 2 treatments per year. Retreatment interval 7 days.
  • tebuconazole/lambda-cyhalothrin (Crossover) at 0.14 to 0.16 lb ai/a. PHI 21 days fodder and silage. REI 24 hr. Retreatment interval 7 days. Do not exceed 0.48 lb ai/a tebuconazole or 0.12 lb ai/a lambda-cyhalothrin per season.
  • zeta-cypermethrin (Mustang) at 0.034 to 0.05 lb ai/a. PHI 7 days for grain, stover and forage. REI 12 hr. Do not exceed 0.2 lb ai/a per season. Retreatment interval 3 days.

Kaur, N. (Ed.). 2023 Pacific Northwest Insect Management Handbook.
© Oregon State University.

Use pesticides safely!

  • Wear protective clothing and safety devices as recommended on the label. Bathe or shower after each use.
  • Read the pesticide label—even if you’ve used the pesticide before. Follow closely the instructions on the label (and any other directions you have).
  • Be cautious when you apply pesticides. Know your legal responsibility as a pesticide applicator. You may be liable for injury or damage resulting from pesticide use.

Trade-name products and services are mentioned as illustrations only. This does not mean that the participating Extension Services endorse these products and services or that they intend to discriminate against products and services not mentioned.