1. Insect
  2. Legume, Grass, and Field Seed Crops
  3. Pests of Alfalfa Grown for Seed

Alfalfa seed-Grasshopper

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Image related to Alfalfa seed-Grasshopper
Redlegged grasshopper
Melanoplus femurrubrum DeGeer
Egg(s) on host
© Ken Gray Insect Image Collection
Image related to Alfalfa seed-Grasshopper
Migratory grasshopper
Melanoplus sanguinipes Fabricius
Female adult
© Ken Gray Insect Image Collection

Includes several species, especially Melanoplus spp.

Pest description and crop damage Both nymphs and adult grasshoppers can cause plant damage. In addition to foliage injury, feeding on blossoms prevents seed formation.

Management-chemical control

  • Beauveria bassiana strain GHA (BotaniGard) at 0.11 to 0.44 lb ai/A in 100 gal. PHI 0 days. This product is potentially pathogenic to honeybees. Avoid applying to areas where honeybees are actively foraging or around beehives. Drift and runoff may be hazardous to aquatic organisms in water adjacent to treated areas. Typically, it takes 7 to 10 days after the first spray to see control. Apply at 5- to 10-day intervals for low to normal pest pressure. For high pest pressure, especially aphids, apply at 2- to 5-day intervals. Repeat applications for as long as pest pressure persists. There is no limit on the number of applications or total amount of product that can be applied in one season.
  • chlorpyrifos (Chlorpyrifos 4E-AG) at 0.5 to 1 lb ai/A. REI 24 hr. Application rates will vary depending on the nozzle droplet type. Toxic to fish, aquatic invertebrates, small mammals and birds. Highly toxic to bees. Buffer zones must be utilized for aquatic areas when using ground boom (25 ft), chemigation (25 ft), orchard airblast (50 ft), and aerial (150 ft). Do not cut or graze alfalfa within 7 days after application of 0.5 pint/A, 14 days after application of 1 pint, and 21 days after application of > 1 pint/A. Labeled for Idaho.
  • diflubenzuron (Dimilin 2L) at 0.031 lb ai/A. PHI 0 days. REI 12 hr. For nymph control only. Do not feed, graze, or cut hay for forage. Not for human consumption. Do not apply at ground level within 25 ft of aquatic habitat, 150 ft if applied by air. SLN ID-000013; OR-0800032; WA-000024.
  • dimethoate (400EC, Dimate 4E) at 0.25 to 0.5 lb ai/A. PHI 10 days. REI 48 hr. For suppression only. Do not apply if crop or weeds are in bloom. Effective only on cutting to which chemical is applied. Do not feed or graze livestock. Do not apply more than once per cutting cycle and more than three times per year. Minimum retreatment intervals of 30 days.
  • gamma-cyhalothrin (Proaxis, Declare) at 0.01 to 0.015 lb ai/A. PHI 1 day for forage, 7 days for hay. REI 24 hr. Do not exceed 0.06 lb ai/A per season or 0.015 lb ai/A per cutting. Do not apply on ground within 25 ft of aquatic habitat, 150 ft if applied by air, or 450 ft if applied from ULV.
  • lambda-cyhalothrin (Serpent 1EC, Warrior II) at 0.02 to 0.03 lb ai/A. PHI 1 day for forage, 7 days for hay. REI 24 hr. Do not apply more than 0.03 lb ai (3.84 fl oz or 0.24 pint of product) per acre per cutting, or more than 0.12 lb ai (15.36 fl oz or 0.96 pint of product) per acre per season. Do not apply on ground within 25 ft of aquatic habitat (groundboom, overhead chemigation, or airblast), 150 ft if applied by air, or 450 ft if applied from ULV. Do not apply while bees are active. Advisable to move bee shelters for 2 to 3 days after application. Avoid application when bees are actively foraging by applying during the early morning or during the evening hours.
  • lambda-cyhalothrin + chlorantraniliprole (Besiege) at 0.03-0.05 lb ai/A. PHI 1 day for forage and 7 days for hay. Do not exceed a total of 31.0 fl oz per year. Do not apply more than 10.0 fl oz per acre per cutting and no more than 1 application per cutting. Avoid application when bees are actively foraging by applying during the early morning or during the evening hours. It may be advisable to remove bee shelters during and for 2 to 3 days following application. Avoid direct application to bee shelters.
  • malathion 8EC at 0.75 to 1.25 lb ai/A. PHI 0 days. REI 12 hr. Not effective below 65ºF. Not recommended for fields pollinated with leafcutters. WA only.
  • Nosema locustae (Nolo Bait)-PHI 0 days. Use as directed.
  • zeta-cypermethrin (Mustang Max) at 0.014 to 0.025 lb ai/A. PHI 3 days for cutting or grazing, 7 days for harvest. REI 12 hr. Allow at least 7 days between applications. Do not exceed 0.05 lb ai/A per cutting or 0.15 lb ai/A per year. Do not apply on ground within 25 ft of aquatic habitat, 150 ft if applied by air, or 450 ft if applied from ULV.