Sugar beet-Cutworm

Subterranean species include

Black cutworm (Agrotis ipsilon)
Glassy cutworm (Apamea devastator)
Redbacked cutworm (Euxoa ochrogaster)

Climbing species include

Army cutworm (Euxoa auxiliaris)
Spotted cutworm (Xestia c-nigrum)
Variegated cutworm (Peridroma saucia)

Pest description and crop damage Several species can cause significant damage to seedling-stage sugar beets, especially in fields where weedy spots or plant debris on the soil surface serve as sites for cutworm overwintering or early-season egg laying. Cutworms generally are nocturnal, remaining by day just under the soil surface; so, often they are not seen until after the plant already has been damaged.

Cutworm larvae are about 1 inch when mature and vary in color from light gray to dark brown, with faint stripes or fine mottles on their smooth, hairless, soft bodies. They curl into a motionless C-shape when disturbed.

Subterranean species feed on roots and stems, cutting off plants at the soil surface. Climbing species hide during the day in soil and either cut off plants at the soil surface or feed in the crown on newest leaves and stems.

Scouting and thresholds No formal economic thresholds exist for cutworm insecticide treatment decisions in sugar beets. Infestations typically are very spotty, usually occurring near weedy patches or along field borders. Consider spot treating infested sites rather than the entire field.

Management-biological control

• Bacillus thuringiensis aizawai (XenTari - live spores of an insect-killing bacterium)-See label for rates. PHI 0 days. Biological insecticide most effective against small, newly hatched larvae. No contact action; larvae must eat treated leaves. Use a spreader-sticker. REI 4 hr. Some formulations are OMRI-listed for organic use.
• Bacillus thuringiensis kurstaki (BioBit HP, Deliver, Dipel DF, Javelin WG, and others - live spores of an insect-killing bacterium)-See label for rates. PHI 0 days. REI 4 hr. Biological insecticide most effective against small, newly hatched larvae of climbing cutworms. No contact action; larvae must eat treated leaves. Use a spreader-sticker. Some formulations are OMRI-listed for organic use.
• GS-omega/kappa-Hxtx-Hv1a (Spear LEP - peptide derived from spider venom)-See label for rates. Tank mix with Bacillus thuringiensis products (Bts) to enhance control. PHI 0 days

Management-chemical control

• alpha-cypermethrin-
  • Postemergence-(Fastac EC, Fastac CS) at 0.014 to 0.025 lb ai/A. PHI 50 days. REI 12 hr. Apply by air or ground equipment using sufficient water to obtain full coverage of foliage (minimum of 2 gallons per acre by air and 10 gal per acre by ground). Apply no more than 0.075 lb ai/A per season. For Fastac CS, do not graze or harvest treated sugar beet tops for livestock feed.
  • At planting-(Fastac CS) at 0.025 lb ai/A. Apply on the soil surface in a 5- to 7-inch band or broadcast in a minimum of 3 to 5 gal/Acre water. PHI 50 days. Do not graze or harvest treated sugar beet tops for livestock feed.
• azadirachtin-Some formulations are OMRI-listed for organic use.
  • (Azatin XL) at 0.01 to 0.02 lb ai/A. Foliar application against larvae. REI 4 hours. Application equipment should be calibrated for no less than three gallons per acre.
  • (Aza-Direct) at 0.0123 to 0.024 lb ai/A and up to 0.0432 lb ai/A under extremely heavy pest infestation.
  • (Debug Trés) at 0.0375 to 0.1054 lb ai/A.
  • (Ecozin Plus) at 0.012 to 0.023 lb ai/A. Spray when pests first appear and repeat after 7-10 days.
• azadirachtin/pyrethrins (Azera and Azera Pro) at 0.0125 to 0.025 lb ai/A, and up to 0.044 lb ai/A under extremely heavy infestation. Dilution in a minimum of 30 gal water per acre is recommended for conventional equipment. May be applied by air at the rate of 0.0125 to 0.025 lb ai/A in a minimum of 25 gal water. Do not repeat more than every 5 to 7 days. OMRI-listed for organic use.
• carbaryl (Carbaryl 4L, Sevin 4F, Sevin 5 Bait, Sevin XLR Plus, Eco-Bran For Grasshoppers, and others) at 0.6 to 1.5 lb ai/A. PHI 28 days. For Carbaryl 4L, Sevin 4F, Sevin 5 Bait, and Sevin XLR Plus, do not apply more than a total of 3 lb ai/A per crop. For Eco-Bran for Grasshoppers, do not apply more than 1.2 lb ai/A per crop.
• clothianidin (NipsIt INSIDE, Lumisure)-Application only by commercial seed treaters; no on-farm seed-treatment application.
• clothianidin/Bacillus firmus I-1582 (Poncho/Votivo)-Application only by commercial seed treaters; no on-farm seed-treatment application.
• clothianidin/beta-cyfluthrin (Poncho Beta)-Application only by commercial seed treaters; no on-farm seed-treatment application.
• esfenvalerate (Asana XL, S-fenvaloStar, Zyrate) at 0.03 to 0.05 lb ai/A as seedling spray. PHI 21 days. Apply as necessary, but do not apply more than 0.15 lb ai/A per season. Apply with ground or air equipment using enough water (at least 2 gal/A) to coverage uniformly.
• methomyl (Annihilate LV, Annihilate SP, Lannate LV, Lannate SP, M1 SP, Nudrin LV, Nudrin SP) at 0.45 lb ai/A for variegated cutworm. PHI for roots 21 days or 30 days if tops are fed to livestock. REI 48 hr. Do not apply more than 4.5 lb ai/A per crop or apply more than 10 times per crop.
• methoxyfenozide (Inspirato 2F, Intrepid 2F, Invertid 2F, Troubadour, Vexer, Withstand, Zylo) at 0.12 to 0.25 lb ai/A. For suppression only. Apply at egg hatch or when signs of feeding occur. PHI 7 days.
• methoxyfenozide/spinetoram (Intrepid Edge) at 0.11 to 0.28 lb ai/A. For suppression only. Apply at egg hatch or first signs of feeding. PHI 7 days.
• neem oil (Ecoworks EC)-See label for rates. OMRI-listed for organic use.
• pyrethrins and piperonyl butoxide (Pyrenone, Pyronyl Crop Spray)-See label for rates.
• spinosad (Seduce) at 0.014 to 0.031 lb ai/A. Soil-applied insecticidal bait that attracts and kills insects; use standard broadcast spreader for broadcast application or standard granular spreader for row application. Do not apply more than four times per crop (more than 0.33 lb ai/A per crop) or less than seven days apart or more than three times in any 30-day period. PHI 3 days. Some formulations are OMRI-listed for organic use.
• terbufos (Counter 20G Lock'n Load, Counter 20G Smartbox) at 1.2 oz ai/1,000 row feet-for suppression only. Apply at planting in a 5- to 7-inch band over the row and lightly incorporate. Do not allow granules to contact seed. Only one application per year. Do not exceed 2 lb ai/A. PHI 150 days.
• zeta-cypermethrin-
  • (Mustang) PHI 50 days. Do not apply more than 0.15 lb ai/A per season (at planting/foliar applications).
    • At planting application-Apply at 0.05 lb ai/A on soil surface in a 5- to 7-inch band, or broadcast in at least 3 to 5 gal/A water.
    • Foliar application-Apply at 0.028 to 0.05 lb ai/A with equipment for ground or air application, using enough water to fully cover foliage.
  • (Mustang Maxx) at 0.014 to 0.025 lb ai/A. PHI 50 days for tops or roots. Do not apply more than 0.075 lb ai/A per season. REI 12 hr. Apply by air or ground using minimum of 2 gal per acre by air and 10 gal per acre by ground.
    • At planting-Apply at 0.025 lb/Ai/A. Apply on the soil surface in a 5- to 7-inch band or broadcast in a minimum of 3 to 5 gal per acre.