Description of the Pest
Flea beetle adults are about 0.13 inch (3 mm) long, shiny, hard beetles. Adults have an enlarged basal segment (femur) on their hind legs, which is used to jump when disturbed. Species differ in color and markings. Larvae are pale and slender. They are most common in spring but can occur any time, especially in fields that are weedy or surrounded by weeds.
Damage
Flea beetles are occasional pests of cole crop seedlings. The adults feed on the underside of leaves, creating small pits or irregularly shaped holes. High numbers of adults can kill or stunt seedlings, which can be economically damaging. Damage to older plants rarely causes economic loss, although their lower, older leaves may have been chewed and damaged.
Larvae do not cause economic damage but can mine leaves or feed on roots.
Management
Use cultural control to prevent flea beetle damage, and regularly monitor crop seedlings and young plants for flea beetles and their damage to help determine whether insecticide application is needed.
Cultural Control
Remove weeds along field margins to prevent adult flea beetles from moving into the crop from weeds.
Organically Acceptable Methods
Use cultural controls in an organically certified crop. Insecticidal soaps sprayed at the cotyledon stage may provide partial control.
Monitoring and Treatment Decisions
Check seedlings and new transplants in the field for flea beetle damage twice per week until plants are well established.
Low numbers can cause economic damage when plants are in the cotyledon or first-leaf stage. Apply an insecticide if several rows are damaged; spot treatment of outside rows or borders may be sufficient. Insecticide baits are not effective. If numbers are high, apply an insecticide to infested fields just before thinning to prevent post-thinning damage.
Once plants have 5 leaves, they can tolerate several beetles per plant without damage. Older plants are even more tolerant. One insecticide application should provide sufficient 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. | ||||
| A. | CARBARYL* | |||
| (Sevin 4F) | 0.5–1 qt | 12 | See comments | |
| MODE-OF-ACTION GROUP NUMBER1: 1A | ||||
| COMMENTS: PHI is 3 days for head and stem cole crops, and 14 days for leafy crops. | ||||
| B. | ESFENVALERATE | |||
| (Asana XL) | 5.8–9.6 fl oz | 12 | See comments | |
| MODE-OF-ACTION GROUP NUMBER1: 3A | ||||
| COMMENTS: Registered for use in broccoli, Chinese broccoli, cabbage, cauliflower, collards, kohlrabi, mustard greens, and tight-heading varieties of Chinese cabbage (napa cabbage). For collard greens and mustard greens, PHI is 7 days. For other registered cole crops, PHI is 3 days. | ||||
| C. | INSECTICIDAL SOAP | |||
| (M-Pede)# | 1–2% (v/v) solution | 12 | 0 | |
| MODE-OF-ACTION: A contact insecticide with smothering and barrier effects. | ||||
| COMMENTS: Provides partial control of flea beetles when plants are in the cotyledon stage. May be phytotoxic on Brussels sprouts and cabbage. Check with organic certifier to determine which products are organically acceptable. | ||||
| D. | CRYOLITE | |||
| (Prokil Cryolite 96) | 8–16 lb | 12 | See comments | |
| MODE-OF-ACTION GROUP NUMBER1: 8C | ||||
| COMMENTS: For use on broccoli, Brussels sprouts, cabbage and cauliflower. Use in cabbage is allowed through a supplemental label (EPA Reg. No. 10163-41). For broccoli, Brussels sprouts, and cauliflower, PHI is 7 days. For cabbage, PHI is 14 days. Must be ingested by the insect. Apply as soon as adults or their feeding damage are observed on seedlings. Can be useful in an insecticide resistance management program. | ||||
| E. | THIAMETHOXAM | |||
| (Platinum) | 5–11 fl oz | 12 | 30 | |
| MODE-OF-ACTION GROUP NUMBER1: 4A | ||||
| COMMENTS: Not registered for use on crops grown for seed. Thiamethoxam and its metabolites (which include the neonicotinoid clothianidin) are highly toxic to bees. This product has potential to leach into groundwater where soils are permeable, particularly where the water table is shallow. Review and follow the California neonicotinoid regulations effective January 1, 2024. Permissible application rates of this insecticide may be lower than label rates if applyin more than one neonicotinoid active ingredient or using more than one application method in the same season. |
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| F. | IMIDACLOPRID | |||
| (Admire Pro) | 1.3 fl oz | 12 | 7 | |
| MODE-OF-ACTION GROUP NUMBER1: 4A | ||||
| COMMENTS: Not registered for use on cole crops grown for seed. Use foliar application for flea beetle control. Effective against larvae only. This product has potential to leach into groundwater where soils are permeable, particularly where the water table is shallow. Review and follow the California neonicotinoid regulations effective January 1, 2024. Permissible application rates of this insecticide may be lower than label rates if applyin more than one neonicotinoid active ingredient or using more than one application method in the same season. |
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| G. | DINOTEFURAN | |||
| (Venom) | 4 oz | 12 | 1 | |
| MODE-OF-ACTION NUMBER1: 4A | ||||
| COMMENTS: Foliar application. Registered for use on broccoli, broccoflower, Brussels sprouts, cabbage, cauliflower, Chinese cabbage, and kohlrabi. Not registered for use on cole crops grown for seed. Highly toxic to bees for more than 38 hours after application. This product has potential to leach into groundwater where soils are permeable, particularly where the water table is shallow. Review and follow the California neonicotinoid regulations effective January 1, 2024. Permissible application rates of this insecticide may be lower than label rates if applyin more than one neonicotinoid active ingredient or using more than one application method in the same season. |
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| H. | ACETAMIPRID | |||
| (Assail 30SG) | Label rates | 12 | See comments | |
| (Assail 70WP) | Label rates | 12 | See comments | |
| MODE-OF-ACTION GROUP NUMBER1: 4A | ||||
| COMMENTS: Maximum application rate varies between head and stem cole crops and leafy cole crops. For head and stem cole crops, PHI is 7 days. For leafy cole crops, PHI is 3 days. This product has potential to leach into groundwater where soils are permeable, particularly where the water table is shallow. | ||||
| ‡ | 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 the two intervals is the minimum time that must elapse before harvest. |
| 1 | Rotate insecticides 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; insecticides with a 1B group number should be alternated with insecticides that have a group number other than 1B. Mode-of-action group numbers are assigned by IRAC (Insecticide Resistance Action Committee). |
| # | Acceptable for use on organically grown produce. |
| * | Permit required from county agricultural commissioner for purchase or use. |