Pasture and grass hay-Armyworm and cutworm

Many species, including
Armyworm (Pseudaletia unipuncta)
Army cutworm (Chorizagrotis auxillaris)
Black cutworm (Agrotis ipsilon)
Glassy cutworm (Apamea devastator)
[No common name] (Protagrotis obscura)

Pest description and crop damage Larvae are 1 to 2 inches long at maturity. All, except glassy cutworm and Protagrotis obscura usually feed above ground on foliage after dark or during conditions of low light intensity. Larvae cause most damage to new seedlings, particularly if the previous crop was heavily infested and the larvae were not controlled.

Management-chemical control

  • azadirachtin (Aza-Direct, Neemix 4.5) at 0.015 to 0.021 lb ai/A. REI 4 hr. PHI 0 days. OMRI-listed for organic use.
  • Bacillus thuringiensis (XenTari, DiPel DF) at 0.5 to 2 lb product/A. PHI 0 days. REI 4 hr. Armyworms only. Most effective on small caterpillars, but use highest recommended rate for fully developed ones. Multiple applications may be necessary for effective control. A spreader sticker may improve performance. Some formulations are OMRI-listed for organic use.
  • beta-cyfluthrin (Baythroid XL) at 0.013 to 0.015 lb ai/A. PHI 0 days for grazing or hay. REI 12 hr. Do not exceed 0.089 lb ai/A per season. Retreatment interval 5 days.
  • bifenthrin (Brigade WSB) at 0.05 to 0.1 lb ai/A. PHI 30 days for forage and hay. REI 12 hr. Retreatment interval 14 days. Do not exceed 0.2 lb ai/A per season.
  • carbaryl (Sevin 4F) at 1 to 1.5 lb ai/A. PHI 14 days. REI 12 hr. Limit 2 treatments per year. Retreatment interval 14 days. Do not exceed 3 lb ai/A per year. Armyworms only.
  • carbaryl (Sevin 5 Bait) at 1.5 lb ai/A. PHI 7 days for harvest or grazing. Limit 2 treatments per year. REI 12 hr. Retreatment interval 14 days.
  • chlorantraniliprole (Coragen, Prevathon) at 0.045 to 0.098 lb ai/A for armyworms, and 0.065 to 0.098 lb ai/A for cutworms. Max rate of Prevathon is 0.067 lb ai/A for armyworms and 0.097 lb ai/A for cutworms. PHI 0 days. REI 4 hr. Retreatment interval 7 days. Do not exceed 0.2 lb ai/A or 4 applications per season.
  • chlorantraniliprole/lambda-cyhalothrin (Besiege, Voliam Xpress) at 0.049 to 0.078 lb ai/A. PHI 0 days for grazing or cut for forage; 7 days for cut grass to be dried and harvested for hay. Retreatment interval 7 days. REI 12 hr. Do not exceed 0.09 lb ai/A lambda- cyhalothrin or 0.2 lb ai/A chlorantraniliprole.
  • cyfluthrin (Tombstone) at 0.025 to 0.03 lb ai/A. PHI 0 days. REI 12 hr. Retreatment interval 5 days. Do not exceed 0.176 lb ai/A per season.
  • diflubenzuron (Dimilin 2L) at 0.03 lb ai/A. PHI 1 day for cutting. REI 12 hr. Must be applied at first sign of hatch and before larvae reach 0.25 inch. Do not exceed 0.03 lb ai/A (0.5 oz ai/A) per cutting or 0.09 lb ai/A (1.5 oz ai/A) per year.
  • gamma-cyhalothrin (Declare) at 0.0075 to 0.0125 lb ai/A. PHI 0 days for grazing or cut for forage; 7 days for cut grass to be dried and harvested. REI 24 hr. Do not exceed 0.045 lb ai/A per season.
  • lambda-cyhalothrin (Warrior II) at 0.015 to 0.03 lb ai/A. PHI 0 days for grazing and forage; 7 days to be dried for hay. REI 24 hr. Do not exceed 0.03 lb ai/A per cutting or 0.09 lb ai/A per season.
  • malathion (Malathion 5EC) at 1.25 lb ai/A. PHI 0 days. REI 12 hr. Armyworms only. One application limit per cutting.
  • methoxyfenozide (Intrepid 2F) at 0.06 to 0.12 lb ai/A. PHI 0 days for grazing, forage; 7 days hay. REI 4 hr. Do not apply more than 0.5 lb ai/A per year. Armyworms only.
  • sodium borate (Prev-Am Ultra) at 50 fl oz/100 gal. PHI 1 day. REI 12 hr. Retreatment interval 7 days.
  • spinosad (Entrust SC) at 0.031 to 0.0625 lb ai/A. PHI 3 days hay or fodder; 0 days pasture/forage. REI 4 hr. Armyworms only. Do not apply more than 3 times in any 21-day period or more than 6 times/ season. Hazardous to honeybees for up to 3 hours post application. Limit 0.186 lb ai/A per season. OMRI-listed for organic use.
  • zeta-cypermethrin (Mustang, Mustang Maxx) -Mustang at 0.035 to 0.05 lb ai/A; Mustang Maxx at 0.0175 to 0.025 lb ai/A. PHI 3 days for cutting or grazing; 7 days for seed. REI 12 hr. Do not apply more than 0.05 lb ai per cutting or 0.15 lb ai per season of Mustang or 0.025 lb ai per cutting and 0.075 lb ai per season of Mustang Maxx. Retreatment interval 7 days.