Alfalfa hay-Western spotted cucumber beetle

Diabrotica undecimpunctata

Pest description and crop damage Adults are green to yellow with 12 black spots on wing covers. They feed on seedlings and retard growth or reduce stands. Occasionally require control on new stands west of the Cascades.

Management-chemical control

The following insecticides are hazardous to bees and should NOT be used if bees are foraging in the alfalfa.

  • beta-cyfluthrin (Baythroid XL) at 0.0125 to 0.022 lb ai/a. PHI 7 days for grazing or cutting. REI 12 hr. Retreatment interval 5 days. Do not exceed 0.044 lb ai/a per cutting or 0.175 lb ai/a total per season. (Group 3A)
  • carbaryl (numerous products) at 1 lb ai/a. PHI 7 days for grazing or cutting. REI 12 hr. Do not apply more than once per cutting. Carbaryl may burn or yellow hay under some conditions (wet foliage, high humidity). Latex-based formulations, such as Sevin XLR Plus, are less hazardous to bees. (Group 1A)
  • chlorantraniliprole/lambda-cyhalothrin (Besiege) at 0.059 to 0.088 lb ai/a. PHI 1 day for forage and 7 days for hay. REI 24 hr. Minimum of 5 days between applications. Do not exceed 0.12 lb ai of lambda-cyhalothrin or 0.2 lb ai of chlorantraniliprole per acre per growing season. Refer to product labels for application limits if products containing gamma-cyhalothrin and products containing lambda-cyhalothrin are to be used in the same season. (Group 28 and 3A)
  • chlorpyrifos (numerous products) at 0.25 to 0.5 lb ai/a. PHI for grazing or cutting is 7 days at 0.25 lb ai/a, 14 days at 0.5 lb ai/a. REI 24 hr. Do not apply any chlorpyrifos products more than four times per season or more than once per cutting. Do not reapply within 10 days of the first application. Certain products can be chemigated by sprinkler irrigation. Minor phytotoxicity possible on new growth. (Group 1B)
  • chlorpyrifos/gamma cyhalothrin (Cobalt) at 0.14 to 0.26 lb ai/a. PHI 14-21 days. REI 24 hr. Do not apply Cobalt nor any other product containing chlorpyrifos more than once per cutting nor more than 4 times per season. Refer to product labels for application limits if products containing gamma-cyhalothrin and products containing lambda-cyhalothrin are to be used in the same season. (Groups 1B and 3A)
  • cyfluthrin (Tombstone) at 0.025 to 0.044 lb ai/a. PHI 7 days for grazing or cutting. REI 12 hr. Retreatment interval 5 days. Do not exceed 0.088 lb ai/a per cutting or 0.35 lb ai/a total per season. (Group 3A)
  • gamma-cyhalothrin (Declare) at 0.01 to 0.015 lb ai/a. PHI 1 day for forage harvest or 7 days for hay harvest. REI 24 hr. Do not exceed 0.015 lb ai/a per cutting or 0.06 lb ai/a per season. Refer to product labels for application limits if products containing gamma-cyhalothrin and products containing lambda-cyhalothrin are to be used in the same season. (Group 3A)
  • lambda-cyhalothrin (Warrior II) at 0.02 to 0.03 lb ai/a. PHI 1 day for forage harvest or 7 days for hay harvest. REI 24 hr. For adult beetle suppression only. Apply only to pure stands. Do not apply when bees are actively foraging. Do not exceed 0.03 lb ai/a per cutting or 0.12 lb ai/a per season. Refer to product labels for application limits if products containing gamma-cyhalothrin and products containing lambda-cyhalothrin are to be used in the same season. (Group 3A)
  • permethrin (numerous products) at 0.1 to 0.2 lb ai/a. PHI 0 days at 0.1 lb ai/a or less, 14 days above 0.1 lb ai/a. REI 12 hr. Do not exceed 0.2 lb ai/a per cutting. Retreatment interval 30 days. (Group 3A)
  • phosmet (Imidan 70-W) at 0.7 to 1 lb ai/a. PHI 7 days for grazing or cutting. REI 5 days. Do not apply more than once per cutting. Do not apply during bloom. Do not use latex- or pineolene-based adjuvants. (Group 1B)