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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 and soil 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 treated area if no contact with anything treated. Group 4.
  • thiamethoxam (Cruiser 5FS) at 1.25mg ai/kernel. Must be administered by seed company.

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.
  • chlorethoxyfos/bifenthrin (SmartChoice HC) at 1.5 to 1.67 oz ai/1,000 row ft; 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. IRAC Group 1B insecticide.
  • 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. Restricted use pesticide.
  • gamma-cyhalothrin (Declare) 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. IRAC Group 3 insecticide.
  • lambda-cyhalothrin (Warrior II) 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. IRAC Group 3 insecticide.
  • 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. Restricted use pesticide. IRAC Group 1.
  • tefluthrin (Force 3G) 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. IRAC Group 3 insecticide.

Adult treatments

  • alpha-cypermethrin (Fastac CS, Fastac EC) 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. IRAC Group 3A insecticide.
  • beta cyfluthrin (Baythroid XL) 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. IRAC Group 3 insecticide.
  • bifenthrin (Brigade 2EC) 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. IRAC Group 3A insecticide.
  • 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. Apply when silking begins and repeat as necessary to maintain control. Group 3A and 28.
  • bifenthrin/zeta-cypermethrin (Hero, Steed) 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. IRAC Group 3A.
  • carbaryl (Sevin 4F) 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) 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. IRAC Group 3 & 28.
  • 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) 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. IRAC group 3A.
  • deltamethrin (Delta Gold) 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. IRAC Group 3.
  • dimethoate (Dimethoate 400 EC) 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. IRAC Group 1B insecticide/miticide
  • esfenvalerate (Asana XL) 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. IRAC Group 3.
  • 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) 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. IRAC Group 22.
  • lambda-cyhalothrin (Warrior II) 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. IRAC Group 3.
  • 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. IRAC Group 1B.
  • methomyl (Lannate SP) 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. Restricted use pesticide. IRAC Group 1A.
  • 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. IRAC Group 3.
  • 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, Mustang MAXX) at 0.034 to 0.05 lb ai/A (Mustang) 0.017 to 0.025 lb ai/A (Mustang MAXX). PHI 7 days for grain, stover and forage. Do not exceed 0.1 lb ai/A (Mustang) 0.2 lb ai/A (Mustang MAXX) per season. REI 12 hr. Retreatment interval 3 days.