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How to Manage Pests

UC Pest Management Guidelines


Adult seedcorn maggot, Delia platura.

Corn

Seedcorn Maggot

Scientific name: Delia platura

(Reviewed 1/06, updated 8/08)

In this Guideline:


DESCRIPTION OF THE PEST

The seedcorn maggot adult is a slender, light gray fly, about 0.2 inch long; it is less robust appearing than the housefly. The whitish eggs are slightly curved with their posterior bluntly rounded. Mature larvae range from 0.2 to 0.25 inch in length, are white to whitish yellow, cylindrical, and taper anteriorly. Pupae are small brown capsules. In California, the seedcorn maggot is abundant primarily in spring, during or following a wet cycle, and is most common in fields containing a high amount of residue from a previous crop or where manure has been spread.

DAMAGE

Seedcorn maggots burrow into corn seeds and prevent germination. Slow emergence and poor stand establishment are signs of seedcorn maggot activity. Where slow, spotty emer­gence is observed, dig up seeds and inspect for maggot feeding. Soil and weather conditions such as cool soil temperature and periods of excessive moisture favoring slow seed germi­nation and seedling emergence increase susceptibility to seedcorn maggot infestation.

MANAGEMENT

A preventive treatment (seed or broadcast) is the best method of control. To reduce attractiveness of a field to egg-laying adults, disc or plow early in the season, incorporating residues from a previous crop and destroying weed growth. Plant under ideal soil and weather conditions to assure rapid seed germination and minimize the seedcorn maggot problem.

Organically Acceptable Methods
Discing to incorporate crop residues and destroy weed growth and planting under ideal conditions are the best way to manage this pest in an organically certified crop.

Common name Amount/Acre** R.E.I.+
(trade name)   (hours)

  Calculate impact of pesticide on air quality
The following materials are listed in order of usefulness in an IPM program, taking into account efficacy, information related to natural enemies and honey bees and environmental impact. Not all registered pesticides are listed. Always read label of product being used.
 
BEFORE PLANTING
A. THIAMETHOXAM
  (Cruiser) 5FS   12
  MODE OF ACTION GROUP NUMBER1: 4A
  COMMENTS: A seed treatment. Use allowed under a supplemental label. Do not apply other neonicotinoid (Group 4A) insecticides within 45 days of planting seed treated with this product.
 
B. CLOTHIANIDIN
  (Poncho)   0
  MODE OF ACTION GROUP NUMBER1: 4A
  COMMENTS: A seed treatment. Do not apply other neonicotinoid (Group 4A) insecticides within 45 days of planting seed treated with this product.
 
** Mix with sufficient water to obtain full coverage.
+ Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing.
1 Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Corn
UC ANR Publication 3443
Insects and Mites
L. D. Godfrey, Entomology, UC Davis
S. D. Wright, UC Cooperative Extension, Tulare County
C. G. Summers, Kearney Agricultural Center, Parlier
C. A. Frate, UC Cooperative Extension, Tulare County
Acknowledgement for contributions to Insect and Mites:
M. J. Jimenez, UC Cooperative Extension, Tulare County

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