Description of the Pest
The seedcorn maggot is the larva of a small, light gray fly that is about 0.15 inch (4 mm) long. The whitish, legless maggots are about 0.3 inch (8 mm) long and attack the planted seed of a number of crops during the winter and early spring months, particularly if there is a cold period that prevents quick germination of the seed. Maggots may overwinter in the soil or hatch from eggs laid in spring.
Damage
The maggot attacks germinating seeds or transplants, but is only a pest early in the season before the soil warms up. Little damage is likely to occur once favorable growing conditions set in. Seedcorn maggots are particularly damaging when residues of the previous crop have not thoroughly decayed before planting cucurbits.
Management
A preventive seed treatment is particularly important when planting in no-till, conservation-till, and when planting through cover crops to prevent seedcorn maggot damage. Additionally, good field sanitation, and production measures that ensure rapid seed germination are important in controlling seedcorn maggots.
Cultural Control
Fields with moist, heavy-textured soil usually have the worst problem with this pest. To reduce attractiveness of the field to egg-laying adults, disc or plow early in the season to incorporate residues from the previous crop and allow time for residues to completely decompose before planting. Destroy weed growth. Avoid planting cucurbits after root crops or cole crops, including cabbage, cauliflower, broccoli, and Brussels sprouts, and after fall tomatoes. Assure rapid seed germination by planting in moist soil and not too deep (1.25 to 1.5 inch depth is ideal for melons) when weather conditions are ideal. The longer the germination the greater the risk of infestation. Late-season planting may avoid the early season infestation of this pest.
Organically Acceptable Methods
Cultural controls are acceptable to use in an organically certified crop.
Monitoring and Treatment Decisions
A preventive seed treatment is the best method of control.
| Common name | Amount per acre | REI‡ | PHI‡ | |
|---|---|---|---|---|
| (Example trade name) | (hours) | (days) | ||
| Not all registered pesticides are listed. The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies, honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Always read the label of the product being used. | ||||
| CAUTION: Do not use treated seed for human consumption, for livestock or poultry, or for oil purposes. Label treated seed as follows: TREATED SEED. DO NOT USE FOR FOOD, FEED, OR OIL. | ||||
| PREHARVEST | ||||
| A. | DIAZINON | |||
| (Diazinon AG 500) | 3–4 qt | 72 | 3 | |
| MODE-OF-ACTION GROUP NUMBER1: 1B | ||||
| COMMENTS: For use in melon fields only; broadcast just before planting and incorporate. Avoid drift and tail water runoff into surface waters. | ||||
| PREPLANT FUMIGATION | ||||
| A. | METAM SODIUM* | |||
| (Vapam) | 75 gal | See label | NA | |
| COMMENTS: Wait at least 14 days after fumigation before planting. Fumigants such as metam sodium are a source of volatile organic compounds (VOCs) but are minimally reactive with other air contaminants that form ozone. | ||||
| SEED TREATMENT | ||||
| A. | THIAMETHOXAM | |||
| (Farmore FI400) | Label rates | See label | NA | |
| MODE-OF-ACTION GROUP NUMBER1: 4A | ||||
| COMMENTS: Seed treatment. Farmore FI400 is not labeled for use in California, but seed treated in and obtained from another state can be legally used in California even for a chemical not registered on cucurbits in California. Contact your retail seed dealer for information and availability. | ||||
| AT PLANTING | ||||
| A. | DIAZINON | |||
| (Diazinon AG 500) | 9–12 oz | 72 | 3 | |
| MODE-OF-ACTION GROUP NUMBER1: 1B | ||||
| COMMENTS: Broadcast apply just before planting and immediately incorporate into the top 4 inches of the soil. | ||||
| B. | BIFENTHRIN | |||
| (Capture LFR) | 3.4 –6.8 oz | 12 | NA | |
| MODE-OF-ACTION GROUP NUMBER1: 3A | ||||
| COMMENTS: Apply as an in-furrow spray directly with the seed during planting; soil surface band directly over the seedline. Sprinkler incorporation is an alternative method. | ||||
| C. | CLOTHIANIDIN | |||
| (Belay) | 9–12 oz | 12 | 21 | |
| MODE-OF-ACTION GROUP NUMBER1: 4A | ||||
| COMMENTS: Apply as an in-furrow spray directly with the seed during planting; can also be applied as a transplant water drench for watermelons. Review and follow the California neonicotinoid regulations effective January 1, 2024. Permissible application rates may be lower and application timing may be restricted if using managed pollinators, applying more than one neonicotinoid active ingredient, or using more than one application method in the same season. |
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| D. | CHLORANTRANILIPROLE | |||
| (Coragen) | 3.5–5 oz | 4 | 1 | |
| MODE-OF-ACTION GROUP NUMBER1: 28 | ||||
| COMMENTS: Apply as an in-furrow spray directly with the seed during planting; can also be applied as a transplant water drench for watermelons. | ||||
| E. | CHLORANTRANILIPROLE / THIAMETHOXAM | |||
| (Durivo) | 10–13 fl oz | 12 | 30 | |
| MODE-OF-ACTION GROUP NUMBER1: 28 / 4A | ||||
| COMMENTS: Apply as an in-furrow spray directly with the seed during planting; can also be applied as a transplant water drench for watermelons. Review and follow the California neonicotinoid regulations effective January 1, 2024. Permissible application rates may be lower and application timing may be restricted if using managed pollinators, applying more than one neonicotinoid active ingredient, or using more than one application method in the same season. |
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| ‡ | Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (PHI) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI. The longer of two intervals is the minimum time that must elapse before harvest. |
| * | Permit required from county agricultural commissioner for purchase or use. |
| 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). |
| NA | Not applicable. |