Corn, sweet-Seedcorn maggot

Delia platura

Pest description, crop damage and life history


Pest Monitoring Slow emergence and poor stand establishment are signs of maggot activity. Where slow, spotty emergence is observed, dig up seed and inspect it for maggot feeding. Cool soil temperature and periods of excessive moisture favoring slow seed germination and seedling emergence increase susceptibility to maggot infestation.

In the Pacific Northwest, no specific monitoring methods have been developed. In other parts of the country, estimates of adult fly activity are obtained from the use of yellow or white sticky traps, water pan traps, and pyramid traps to assist in determining the necessity and timing of treatments. Treatments for seedcorn maggot are preventive. Consider them for fields that are high in organic matter or undecomposed organic material, or that have had previous maggot problems. To assess potential infestation levels prior to planting, place a cut potato or other vegetable or fruit in the field and apply baker's yeast with some water to the cut surface. Leave the bait for several hours and return to look for the presence of adult seedcorn maggot flies as they are attracted to carbon dioxide.

If you are planning to use untreated corn seed in a certified organic planting, sow a handful of seeds several places in the field, water, and flag them one week prior to your field planting date. Inspect the test seeds the day prior to planting the field. If 50-75% of the trial seeds are infested with seedcorn maggot, consider delaying or abandoning the sowing of untreated seed in the field for this growing season.

Management-cultural control

Avoid planting in soils that are high in undecomposed organic matter, such as fields just coming out of pasture or that are very weedy. Use herbicides to kill cover crop strips 3 to 4 weeks before seeding. In soils amended with animal manures, allow adequate time for the manure to break down before planting, a minimum of 3 to 4 weeks. The smell of decomposing organic matter or manure attracts egg laying adult females. Avoid planting successive rotations of corn crops.

Early spring-planted crops are more likely to be damaged when the soil is too cool for rapid germination and emergence. If serious infestations are expected, wait until the soil warms up in spring. When planting, use a chain drag or similar implement behind the drill to cover the seed row. Consider planting into a "stale" seedbed. Use an appropriate insecticide in the seed box at planting if problems are expected.

Management-chemical control: HOME USE

  • bifenthrin (sometimes as a mix with zeta-cypermethrin).
  • gamma-cyhalothrin
  • lambda-cyhalothrin
  • pyrethrins-Some formulations are OMRI-listed for organic use.
  • zeta-cypermethrin

Management-chemical control: COMMERCIAL USE

Seed treatment

  • imidacloprid (Gaucho 480F) at 0.125 to 0.5 to 1 oz ai/cwt of seed as a slurry treatment. Not registered for use in OR.
  • permethrin + carboxin (Kernel Guard Supreme) at 1.5 oz of formulated product per 42 lb seed (2 oz per 56 lb seed). REI 12 hr. Planter box treatment. Not registered for use in WA.

Soil treatment

  • Bacillus amyloliquefaciens (Ethos XB) at 0.08 to 0.2 lb ai/A applied with liquid fertilizer at plant. REI 12 hr.
  • beta-cyfluthrin (Baythroid XL) at 0.013 to 0.022 lb ai/A soil application. REI 12 hr. Do not exceed a total of 0.22 lb ai/A per growing season.
  • bifenthrin (Capture LFR) at 0.04 to 0.16 lb ai/A at planting; 0.047 to 0.062 lb ai/A pre-plant incorporated. REI 12 hr. Do not exceed 0.2 lb ai/A per season.
  • bifenthrin/IBA (Empower 2) at 0.002 to 0.006 lb ai/1,000 linear feet of row. PHI 30 days. REI 24 hr. Do not exceed 0.1 lb ai/A at plant application. Not registered in OR.
  • chlorethoxyfos/bifenthrin (Smart Choice 5G) at 3 to 3.5 oz /1,000 row ft. REI 48 hr, or 72 hr if annual rainfall is less than 25 inches.
  • clothianidin (Poncho 600) at 0.25 to 0.5 mg ai/kernel seed treatment. Not for use in hopper-box, slurry-box or similar types. Use in liquid or slurry treaters.
  • cyfluthrin (Tombstone) at 0.031 to 0.44 lb ai/A soil treatment. PHI 0 days. REI 12 hr.
  • gamma-cyhalothrin (Declare) at 0.0008 lb ai/1,000 row ft. REI 24 hr. Do not exceed 0.024 lb ai/A.
  • lambda-cyhalothrin (Warrior II) at 0.005 lb ai/1,000 ft of row soil treatment. REI 24 hr. Do not harvest for feed or graze livestock for 21 days. Do not exceed 0.48 lb ai/A per season.
  • phorate (Thimet 20G) at 0.9 to 1.2 oz ai/1,000 row ft. PHI (see label). REI (see label). Apply at planting time or cultivation. Do not exceed 1.3 lb ai/A per year. Limit 1 treatment.
  • tefluthrin (Force 3G) at 0.0075 to 0.011 lb ai/1,000 row ft (0.12 to 0.15 oz ai/1,000 row ft). REI 48 hr. Use either at planting or lay-by. Only one application per year.
  • thiamethoxam (Cruiser 5FS) at 0.125 to 0.80 mg per kernel (formulated product) planter box treatment, seed treatment.
  • thiamethoxam/Abamectin (Avicta Complete Corn 250). Seed treatment for certified seed treatment facilities only.