Broccoli, Brussels sprout, cabbage, cauliflower-Cutworm

Includes

Black cutworm (Agotis ipsilon)
Variegated cutworm (Peridroma saucia)

Pest description, crop damage and life history

See:

Pest monitoring Pheromone traps can be used to monitor for cutworms. Moth counts in excess of two black cutworm moths per trap per day indicate significant egg laying pressure. It is useful to check moth counts prior to making a pesticide application decision at planting.

If the cutworm population is reducing the plant stand, treat during the seedling stage. Frequently, the damage is most serious at the edges of a field, but stand loss can occur in a spotty pattern throughout the field.

Usually, it is necessary to dig in the soil to find black cutworm larvae and to determine the extent of the infestation and the size of the cutworms involved. Larvae normally hide under debris on the soil surface during the day, but are active, voracious feeders at night.

Since extensive damage may occur in a short period of time, inspect plant beds and newly set plants frequently. In North Carolina, an economic threshold of 5% injured plants has been established for cutworms infesting newly set or young plants (within 3 weeks after transplanting). In Ontario, Canada, the guideline for black cutworm on many seedling vegetables is also 5% plants infested.

Management-biological control

Cutworms are attacked by a number of predators, parasites, and diseases. Many of these natural control agents are not effective on pale western and black cutworms because of their subterranean nature. It is not known if any of these natural enemies can control cutworm populations, but their presence should be noted.

Management-cultural control

Cutworms are most injurious in fields with high plant residue. Historically, cutworms are a problem in early, spring-seeded seedling fields. Tillage prior to seeding is an effective means of preventing cutworm damage. A thorough harrowing may provide adequate control when cutworms are feeding actively in established fields.

Weed control is important. Lambsquarters and wild mustard attract egg-laying females and provide a source of food for larvae. Fall tillage can help destroy overwintering pupae.

Home gardeners: Control weeds, grasses, and debris in the vegetable garden that provide cover; hand-pick cutworm larvae, using a flashlight to find them, if practical. Scratch the soil at the base of plants to find larvae in the daytime.

Management-chemical control: HOME USE

Apply any one of these materials to the soil surface at first sign of cutworm activity. Consult label. Minimum preharvest interval (PHI) varies with crop. Difficult to control. Where cutworms are on the soil surface, a carbaryl drench, when bees are not present, may help.

  • azadirachtin (neem oil)-Some formulations are OMRI-listed for organic use.
  • bifenthrin
  • Bacillus thuringiensis var. kurstaki (Bt)-Some formulations are OMRI-listed for organic use.
  • carbaryl
  • cyfluthrin
  • cyhalothrin
  • esfenvalerate-Do not use on Brussels sprout.
  • gamma-cyhalothrin
  • insecticidal soap-Some formulations OMRI-listed for organic use.
  • kaolin-Applied as a spray to foliage, it acts as a repellent to some insect pests. Some formulations are OMRI-listed for organic use.
  • lambda-cyhalothrin
  • permethrin
  • plant essential oils (rosemary, etc.)-Some have demonstrated efficacy against lepidopteran larvae. Some formulations are OMRI-listed for organic use.
  • pyrethrins (often combined with other ingredients)-Some formulations are OMRI-listed for organic use.
  • spinosad-Some formulations are OMRI-listed for organic use.
  • zeta-cypermethrin

Management-chemical control: COMMERCIAL USE

  • alpha-cypermethrin (Fastac EC) at 0.014 to 0.025 lb ai/a. PHI 1 day. REI 12 hr. Retreatment interval 7 days. Do not exceed 0.075 lb ai/a per season.
  • bifenthrin (Capture LFR) 0.04 to 0.08 lb ai/a at planting in furrow or broadcast to soil surface. Do not exceed 0.1 lb ai/a per season as an at plant application.
  • Bacillus thuringiensis (Javelin) 0.12 to 1.5 lb/a. PHI 0 days. REI 4 hr. Armyworm only. Add an appropriate spreader-sticker to enhance control. Most effective on small larvae. Some formulations are OMRI-listed for organic use.
  • beta-cyfluthrin (Baythroid XL) at 0.007 to 0.013 lb ai/a. PHI 0 days. REI 12 hr. Retreatment interval 7 days. Do not exceed 0.1 lb ai/a per season.
  • beta-cyfluthrin/imidacloprid (Leverage 360) at 0.07 lb ai/a. PHI 7 days. REI 12 hr. Retreatment interval 7 days. Do not exceed 0.1 lb ai/a beta-cyfluthrin or 0.2 lb ai/a imidacloprid per season.
  • bifenthrin (Brigade WSB, Sniper) at 0.033 to 0.1 lb ai/a. PHI 7 days. REI 12 hr. Do not exceed 0.5 lb ai/a per year. Do not make more than five applications after bloom. Retreatment interval 7 days.
  • bifenthrin/IBA (Empower 2) at 0.04 to 0.1 lb ai/a. PHI 7 days. REI 5 days. Retreatment interval 7 days. Do not exceed 0.5 lb ai/a per season.
  • bifenthrin/imidacloprid (Brigadier) at 0.06 to 0.095 lb ai/a. PHI 7 days. REI 12 hr. Do not exceed 0.24 lb ai/a imidacloprid and 0.24 lb ai/a bifenthrin as a foliar application. Retreatment interval 7 days. Maximum 5 treatments only after bloom.
  • bifenthrin/zeta-cypermethrin (Hero) at 0.04 to 0.1 lb ai/a. PHI 7 days. REI 12 hr. Retreatment interval 7 days. Do not exceed 0.45 lb/a per season. Limit 5 applications after bloom.
  • carbaryl (Sevin 5 Bait) at 2 lb ai/a as granule. PHI 3 days. REI 12 hr. Retreatment interval 7 days. Do not exceed 3 treatments per year. Toxic in aquatic habitats.
  • chlorantraniliprole/lambda-cyhalothrin (Voliam Xpress) at 0.049 to 0.078 lb ai/a. PHI 3 days. REI 18 hr. Retreatment interval 5 days. Do not exceed 0.24 lb ai of lambda-cyhalothrin or 0.2 lb ai of chlorantraniliprole per acre per growing season.
  • chlorpyrifos (Lorsban 75WG) at 0.5 to 1 lb ai/a. PHI 21 days. REI 24 hr (3 days for cauliflower). Retreatment interval 7 days. Do not exceed 3 treatments per season. Retreatment interval 10 days.
  • chlorpyrifos (Lorsban Advanced 2ee) direct seeded or transplant at 2.25 lb ai/a (broccoli, cabbage, Brussels sprout) 1.88 lb ai/a (cauliflower). PHI 30 days. REI 24 hr, 3 days for cauliflower. Incorporate into 2 to 4 inches of soil. WA & OR only.
  • chlorpyrifos/gamma-cyhalothrin (Cobalt) at 0.26 to 0.52 lb ai/a. PHI 21 days. REI 24 hr. Limit 3 applications of chlorpyrifos products. Retreatment interval 10 days. Do not exceed 2.25 lb ai/a per year. Brussels sprout only.
  • Chromobacterium subtsugae (Grandevo) at 0.3 to 0.9 lb ai/a per 100 gal. PHI 0 days. REI 4 hr. OMRI-listed for organic use.
  • cryolite (Kryocide) at 7.7 to 15.4 lb ai/a. PHI 7 days for broccoli, cauliflower, and Brussels sprout, and 14 days for cabbage. REI 12 hr. Do not exceed 92 lb ai/a per season. OMRI-listed for organic use.
  • cyfluthrin (Tombstone) at 0.013 to 0.025 lb ai/a. PHI 0 days. REI 12 hr. Retreatment interval 7 days. Do not exceed 0.2 lb/a per season. Toxic to bees.
  • cypermethrin (Holster) at 0.05 to 0.1 lb ai/a. PHI 1 day. REI 12 hr. Retreatment interval 7 days. Do not exceed 0.6 lb ai/a per season.
  • diazinon (Diazinon 50) at 2 to 4 lb ai/a broadcast just before planting and immediately incorporate. REI 4 days.
  • esfenvalerate (Asana XL) at 0.03 to 0.05 lb ai/a. PHI 3 days. REI 12 hr. Do not use on Brussels sprout. Do not exceed 0.4 lb ai/a per year.
  • gamma-cyhalothrin (Declare) at 0.0075 to 0.0125 lb ai/a. PHI 1 day. REI 24 hr. Do not exceed 0.12 lb al/a per season.
  • lambda-cyhalothrin (Warrior II) at 0.015 to 0.025 lb ai/a. PHI 1 day. REI 24 hr. Retreatment interval 5 days. Do not exceed 0.24 lb ai/a per year.
  • lambda-cyhalothrin/thiamethoxam (Endigo ZC) at 0.064 lb ai/a. PHI 1 day. REI 24 hr. Retreatment interval 7 days. Do not exceed 0.24 lb ai of lambda-cyhalothrin or 0.172 lb ai/a of thiamethoxam per season.
  • methomyl (Lannate SP) at 0.45 lb ai/a. PHI 1 day for cabbage; 3 days for others. REI 48 hr. Do not exceed 7.2 lb ai/a for cabbage and cauliflower and 5.4 lb ai/a for Brussels sprout.
  • permethrin (Loveland Permethrin) at 0.1 to 0.2 lb ai/a for cabbage only. PHI 1 day. REI 12 hr. Do not exceed 1 lb ai/a on cabbage per year.
  • permethrin (Loveland Permethrin Cutworm Bait) at 0.05 to 0.1 lb ai/a (cauliflower and Brussels sprout) and 0.01 to 0.2 lb ai/a (broccoli and cabbage). PHI 1 day. REI 12 hr. Do not exceed 0.4 lb ai/a on cabbage, cauliflower & Brussels sprout and 0.8 lb ai/a broccoli per season.
  • zeta-cypermethrin (Mustang) at 0.028 to 0.05 lb ai/a. PHI 1 day. REI 12 hr. Do not exceed 0.3 lb ai/a per year. Retreatment interval 7 days.