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  3. Field and Silage Corn Pests

Field and silage corn-Corn rootworm beetle

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Image related to Field and silage corn-Corn rootworm
Western corn rootworm
Diabrotica virgifera virgifera LeConte
Egg(s) on host
© Ken Gray Insect Image Collection
Image related to Field and silage corn-Corn rootworm
Western corn rootworm
Diabrotica virgifera virgifera LeConte
Immature
© Ken Gray Insect Image Collection
Image related to Field and silage corn-Corn rootworm
Western corn rootworm
Diabrotica virgifera virgifera LeConte
Showing damage on roots
© Ken Gray Insect Image Collection
Image related to Field and silage corn-Corn rootworm
Western corn rootworm
Diabrotica virgifera virgifera LeConte
Adult
© Ken Gray Insect Image Collection

Diabrotica spp.

Pest description and crop damage Also known as Western corn rootworm. West of the Cascades D. undecimpunctata is most common; east of the Cascades D. virgifera is common. Both overwinter in egg stage in the soil. Mature larvae are 0.5 inch long, pale yellow, with a brown head and dorsal anal plate. Larvae feed on and mine into corn roots causing stunting and lodging of plants and stand reduction. After feeding for several weeks, larvae pupate in the soil. Adult emergence varies based on temperature and humidity. Adult rootworm females need to feed for a few weeks prior to egg laying in the top 8 inches of soil.

Management-cultural control

Crop rotation helps to reduce infestations from D. virgifera as eggs overwinter in soil. The adults of D. undecimpunctata overwinter, therefore crop rotation is not as important in managing this species. Early planting is also useful as it allows for greater root development before infestation can impact plant growth.

Management-chemical control

Seed treatments

  • abamectin/thiamethoxam (Avicta Duo Corn)-Requires tank mix. Apply as slurry to corn seed. Consult label.
  • Bacillus thuringiensis (Bt) (Smartstax Pro Enlist). Must be used in conjunction with Bt corn. 5% refuge area not containing corn with Bt technology is required.
  • clothianidin (Lumisure, Nipsit Inside, Poncho 600 Seed Treatment) at 0.044 to 0.88 lb ai per 100 lb of seed. Seed treated with Lumisure must be colored with EPA approved dye. All seed require minimum depth of 0.5 in. Do not plant non-listed crops in same area less than 4 months after planting treated seed. Group 4A
  • Chromobacterium subtsugae (Grandevo) bioinsecticide at 0.05 to 0.1 lb ai/A per 1,000 row feet (1.0 to 3.0 lb product /A). PHI 0 days. REI 4 hr. OMRI-listed for organic use.
  • imidacloprid (Attendant 600 FS, Dyna-Shield Imidacloprid 5, Gaucho 480 Flowable and others) Seed treatment at 0.312 to 0.391 lb ai/ 50 lb of seed. (REI 12 hr unless soil-injected or soil-incorporated allows workers to enter the area treated area if no contact with anything treated. Group 4.
  • thiamethoxam (Cruiser 5FS) at 1.25mg ai/kernel.

Larvae treatments

  • azadirachtin (Aza-Direct, Azaguard and several formulations) biological insecticide/nematicide at 0.02 to 0.35 lb ai/A. PHI 0 days. REI 4 hr. Some formulations are OMRI-listed for organic use.
  • Bacillus amyloliquefaciens D747 TGAI/bifenthrin (Ethos 3D, Ethos XB) at 0.04 to 0.2 lb bifenthrin ai/A. Do not exceed 0.3 lb bifenthrin on field corn per season. REI 12 hr. PHI Group 3A insecticide, Group 44 fungicide.
  • bifenthrin (Fanfare EC, Sniper LFR, Capture, and several others)-See label for specific rates. Multiple formulations with varying rates. PHI 30 days. REI 24 hr. Do not exceed 0.3 lb ai/A foliar and at planting plus foliar application per season.
  • bifenthrin/chlorethoxyfos Group 1B insecticide applied as T-band over the row or in furrow at time of planting.
  • SmartChoice 5G application rate of 3.0 to 3.5 oz/100 ft. REI 2 days or 3 days where annual rainfall is less than 25 inches. Apply with Smartbox system. Do not exceed one application per year.
  • SmartChoice HC application rate at 1.15 to 1.67 oz/1,000 row ft. See spacing charts in label for actual application rates per A. REI 2 days or 3 days where annual rainfall is less than 25 inches. Apply with Smartbox system. Do not exceed one application per year.
  • chlorethoxyfos/bifenthrin (SmartChoice 5G, SmartChoice HC) Group 1B insecticide-SmartChoice HC granular application rate at 1.5 to 1.67 oz ai/1,000 row ft; SmartChoice 5G 4.5 to 5.0 oz/100 ft of row with 30-inch row spacing in field and seed corn. REI 2 days or 3 days where annual rainfall is less than 25 inches. T-band over the row or apply in-furrow. Apply with Smartbox system. Do not exceed one application per year.
  • ethoprop (Mocap 15G) nematicide/insecticide at 1.2 oz ai/1,000 row ft. REI 48 hr or 72 hr where annual rainfall is less than 25 inches. One application per season. Incorporate in band above seed row.
  • gamma-cyhalothrin (Declare) Group 3 insecticide at 0.0025 lb ai/1,000 row ft at planting. REI 24 hr. Do not exceed 0.045 lb ai/Acre at plant and 0.06 lb ai/A per season.
  • lambda-cyhalothrin (Warrior II) Group 3 insecticide at 0.005 lb ai/1,000 row ft (planting). PHI 21 days. REI 24 hr. Do not exceed 0.12 lb ai/A from at plant and foliar applications.
  • phorate (Thimet 20G) at 0.056 to 0.075 lb ai/1,000 row ft at plant or cultivation, broadcast or banded but not in-furrow. PHI 30 days to cutting or forage. REI 48 hr. Use only once per season.
  • tefluthrin (Force 3G) Group 3 insecticide at 0.0075 to 0.094 lb ai/1,000 row ft. REI 0 hr. T-band or in-furrow at planting. Do not exceed 0.327 lb ai/A per year. Use only once per season.
  • terbufos (Counter 15G) at 0.056 to 0.075 lb ai/1,000 row ft. Do not exceed 1.3 lb ai/A per season. REI 48 hr or 72 hr if annual rainfall is less than 25 inches. May be side-dressed at cultivation time if preplant treatment was not made. To be effective, apply before corn is 12 inches high.

Adult treatments

  • alpha-cypermethrin (Fastac CS, Fastac EC) Group 3A insecticide at 0.017 to 0.025 lb ai/A. REI 12 hr. PHI 30 days grain and stover; 60 days forage. Retreatment interval 3 days. Do not exceed 0.075 lb ai/A per season.
  • beta cyfluthrin (Baythroid XL) Group 3 insecticide at 0.013 to 0.022 lb ai/A (1.6 to 2.8 fl oz/A). PHI 0 days for green forage and 21 days for grain or fodder. REI 12 hr. Maximum 2.8 fl oz/A in 7-day interval. Do not exceed four applications or 0.088 lb ai/A per season.
  • bifenthrin (Brigade 2EC) Group 3A insecticide at 0.033 to 0.1 lb ai/A (2.1 to 6.4 fl oz/A). PHI 30 days for harvest, grazing, or cutting for feed. REI 12 hr. Do not apply more than 0.3 lb ai/A per season. Rootworm adults only.
  • bifenthrin/chlorantraniliprole (Elevest) at 0.084 to 0.167 lb ai/A. REI 12 hr. PHI 30 days. No more than three applications per year. Do not apply more than a total of 0.2 lb ai/A of chlorantraniliprole and 0.3 lb ai/A of bifenthrin per year. Group 3A and 28.
  • bifenthrin/zeta-cypermethrin (Hero, Steed) Group 3A insecticide at 0.04 to 0.1 lb ai/A (4.5 to 11.2 fl oz/A). Only for use on corn rootworm adults. PHI 30 days grain and stover; 60 days forage. REI 12 hr. Do not graze for 30 days after treatment. Do not exceed 0.1 lb ai/A at-plant application, or 0. 0.099 lb/A zeta-cypermethrin and 0.398 lb/A bifenthrin per year.
  • carbaryl (Sevin 4F) insecticide at 1 to 2 lb ai/A. PHI 14 days for forage or silage, 48 days for grain or fodder. REI 24 hr. Do not exceed four applications or 8 lb ai/A per season. Re-treat every 14 days. Latex-based formulations, such as Sevin XLR Plus, are less hazardous to bees.
  • chlorantraniliprole/lambda-cyhalothrin (Besiege) Group 3 & 28 insecticide at 0.052 to 0.08 lb ai/A (6.0 to 10.0 fl oz/A). PHI 21 days. REI 24 hr. As part of an aerial applied corn rootworm control program, use minimum of 9.0 fl oz/A. Do not exceed 0.12 lb ai of lambda-cyhalothrin or 0.2 lb ai of chlorantraniliprole per acre per growing season. Retreatment interval 7 days.
  • Chromobacterium subtsugae (Grandevo) bioinsecticide at 0.6 to 0.9 lb ai/A per 100 gal. PHI 0 days (2.0 to 3.0 lb product /A). REI 4 hr. OMRI-listed for organic use.
  • cyfluthrin (Tombstone) insecticide at 0.025 to 0.044 lb ai/A (1.6 to 2.8 oz/A). PHI 0 days for green forage and 21 days for grain or fodder. REI 12 hr. Retreatment interval 7 days. Do not exceed four applications or 0.175 lb ai/A per season.
  • deltamethrin (Delta Gold) Group 3 insecticide at 0.018 to 0.022 lb ai/A (1.5 to 1.9 fl oz/A). PHI 21 days for grain or fodder, or 12 days for forage or grazing. REI 12 hr. Do not apply more than 0.095 lb ai/A per season. Retreatment interval 21 days. Limit 5 treatments per year.
  • dimethoate (Dimethoate 400 EC) Group 1B insecticide/miticide at 0.33 to 0.5 lb ai/A (0.6 to 1 pint/A). PHI 14 days forage; 28 days grain. REI 48 hr. Do not exceed 0.5 lb ai/A per season. Do not apply if bees are foraging actively.
  • esfenvalerate (Asana XL) Group 3 insecticide at 0.03 to 0.05 lb ai/A (5.8 to 9.6 fl oz/A). PHI 21 days. REI 12 hr. Do not exceed 0.25 lb ai/A per season.
  • GS-omega/kappa-Hxtx-Hv1a (Spear Biological Insecticide) at 0.8 lb ai/A. PHI 0 days. REI 4 hr. Do not exceed 2 lb ai/A per year.
  • indoxacarb (Steward EC) Group 22 insecticide at 0.059 to 0.11 lb ai/A. PHI 14 days grain, 1 day forage, fodder, silage. REI 12 hr. Limit 2 treatments. Do not exceed 0.22 lb ai/A per year.
  • lambda-cyhalothrin (Warrior II) Group 3 insecticide at 0.02 to 0.03 lb ai/A. PHI 21 days. REI 24 hr. Do not apply more than 0.12 lb ai/A per season, 0.06 lb ai/A after silk initiation, or 0.03 lb ai/A after milk stage.
  • malathion (Gowan Malathion 8, Fyfanon 8 lb Emulsion and other formulations) at 0.6 to 1 lb ai/A. PHI 5 days for Gowan. REI 12 hr. Limit 2 treatments per year. Retreatment interval 7 days. PHI 7 days. REI 72 hr for detasseling, 12 hr for other activities for Fyfanon 8 lb Emulsion. Group 1.
  • methomyl (Lannate SP) Group 1A insecticide at 0.22 to 0.45 lb ai/A. PHI 21 days for ears, 3 days for forage, and 21 days for fodder. REI 48 hr. Do not exceed 2.25 lb ai/A or 5 treatments per season. Retreatment interval 5 to 7 days.
  • permethrin (Ambush 25W) wettable powder insecticide at 0.1 to 0.2 lb ai/A. PHI 0 days for forage, 30 days for grain harvest or fodder. REI 12 hr. Allow 6 days between applications. Do not apply more than 0.6 lb ai/A per season.
  • tebuconazole/lambda-cyhalothrin (Crossover) Group 3 fungicide/insecticide at 0.14 to 0.16 lb ai/A. PHI 21 days fodder and silage. REI 24 hr. Retreatment interval 7 days. Do not exceed 0.48 lb ai/A tebuconazole or 0.12 lb ai/A lambda-cyhalothrin per season.
  • zeta-cypermethrin (Mustang) Group 3A insecticide at 0.034 to 0.05 lb ai/A. PHI 7 days for grain, stover and forage. Do not exceed 0.2 lb ai/A per season. REI 12 hr. Retreatment interval 3 days.