Description of the Pest
Flea beetle adults are 0.12 inch (3 mm), shiny beetles with enlarged hind legs that allow them to jump like fleas. The palestriped flea beetle has a broad white stripe down each brown wing. The potato flea beetle is a uniform black color.
The larvae live in the soil, are slender, whitish, and about 0.25 inch (6 mm) long when mature.
Damage
Adult flea beetles do most of their damage by feeding on the undersides of leaves, leaving small pits or irregularly shaped holes on the leaves. Large populations can kill or stunt seedlings. Older plants rarely suffer economic damage although their older leaves may be damaged.
In the Imperial and San Joaquin Valleys, larvae are known to cause serious damage by feeding on the roots. Wounds on the surface of the taproot often follow a straight or curved line down on side of the root. This damage is easily confused with cavity spot symptoms. Cavity spot lesions are elliptical and more sunken, are more randomly scattered on the root surface, and tend to be more concentrated on the upper third of the root.
Management
Cultural Control
Remove weeds along field margins and deeply disk plant residue in infested fields after harvest.
Organically Acceptable Methods
Use cultural controls in a certified organic crop.
Monitoring and Treatment Decisions
Check newly emerged seedlings twice weekly for flea beetle damage until plants are well established. Relatively low populations can cause economic damage when plants are in the cotyledon or first-leaf stages. Apply insecticides if you find several damaged rows; spot treatment of outside rows or borders may be sufficient. Baits are not effective.
Once plants have several true leaves, they can tolerate several beetles per plant without damage. Older plants are even more tolerant. Insecticide treatment should rarely be required, but if it is, one application should suffice. However, chemical treatment may disrupt biological control of aphids and whiteflies. Encourage buildup of beneficial insects by avoiding the use of nonselective pesticides and by protecting their habitat.
Pesticides and Natural Enemy Releases
Not all registered pesticides are listed. The following are ranked by their IPM value, with the most effective and least harmful to natural enemies, honey bees, and the environment listed at the top of the table. When choosing a pesticide, consider information related to water and air quality, resistance management, and the pesticide's properties and application timing. Use PestManage to compare summarized management options for different pests in the same crop. Always carefully read the label of the product being used and take all necessary precautions when handling pesticides.
| Rank | Active ingredient | Example trade name | Group | Group Order | MoA 1 | Amount per acre | REI (hours) ‡ | PHI (days) ‡ | Comments | Selectivity 2 | Bees 3 | Predatory mites | Predators 4 | Parasitoids 4 | Residue duration 5 | Leaching(fish) 6 | Adsorbed runoff(fish) 7 | Solution runoff(human) 8 | Leaching(human) 9 | Solution runoff(human) 10 | Last updated 11 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
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|
Baythroid XL | Application Timing Varies (See UC IPM Pest Management Guidelines and Label) | 8 |
3A |
2.8 fl oz | 12 | 0 | Ground application with 30 gallons per a... | broad | — | high | high | moderate | intermediate | intermediate | extra high | very low | very low | 09/2024 | ||
| Sevin XLR Plus | Application Timing Varies (See UC IPM Pest Management Guidelines and Label) | 8 |
1A |
0.5–1 qt | 12 | 3 | — | broad | — | high | high | long | low | low | intermediate | low | low | 09/2024 | |||
|
|
Asana XL | Application Timing Varies (See UC IPM Pest Management Guidelines and Label) | 8 |
3A |
5.8–9.6 fl oz | 12 | 7 | Lower rate should suffice. Highly toxic... | broad | — | moderate | high | moderate | high | intermediate | extra high | low | intermediate | 09/2024 | ||
|
|
Actara | Application Timing Varies (See UC IPM Pest Management Guidelines and Label) | 8 |
4A |
1.5–3 fl oz | 12 | 7 | Do not spray directly or allow to drift... | narrow | — | moderate/high | moderate/high | moderate | very low | very low | low | high | high | 09/2024 | ||
|
|
Mustang | Application Timing Varies (See UC IPM Pest Management Guidelines and Label) | 8 |
3A |
3.4–4.3 fl oz | 12 | 1 | Highly toxic to bees; do not spray direc... | broad | — | moderate | moderate | moderate | intermediate | low | extra high | low | high | 09/2024 |
Legend
- ‡ a b Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without personal protective equipment. 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.
- * a Permit required from county agricultural commissioner for purchase or use.
- 1 ↩ Group numbers for insecticides and miticides are assigned by the Insecticide Resistance Action Committee (IRAC). Insecticides with unknown modes of action are assigned mode-of-action group numbers (MoAs) that begin with UN. Rotate pesticides 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.
- 2 ↩ Range of insect and mite groups affected by a pesticide. Broad means the pesticide affects most groups of insects and mites; narrow means the pesticide affects only a few specific groups.
- 3 ↩ Risk of harm to honey bees. For more information, see Bee Precaution Pesticide Ratings.
- 4 a b Risk of harm to parasitoids and general predators. Toxicities are averages of reported effects and should be used only as a general guide. Actual toxicity of a specific insecticide depends on factors including the application rate, environmental conditions, and the life stage and species of a parasitoid or predator.
- 5 ↩ Length of time residue affects natural enemies. Short means hours to days; moderate means days to 2 weeks; and long means many weeks or months.
- 6 ↩ Risk of harm to fish from leaching, based on USDA Natural Resources Conservation Service Windows Pesticide Screening Tool (WIN-PST).
- 7 ↩ Risk of harm to fish from adsorbed runoff, based on USDA Natural Resources Conservation Service Windows Pesticide Screening Tool (WIN-PST).
- 8 ↩ Risk of harm to fish from solution runoff, based on USDA Natural Resources Conservation Service Windows Pesticide Screening Tool (WIN-PST).
- 9 ↩ Risk of harm to humans from leaching, based on USDA Natural Resources Conservation Service Windows Pesticide Screening Tool (WIN-PST).
- 10 ↩ Risk of harm to humans from solution runoff, based on USDA Natural Resources Conservation Service Windows Pesticide Screening Tool (WIN-PST).
- 11 ↩ Date information was last updated in the UC IPM Pest Management Guidelines.
UC IPM Pest Management Guidelines: Carrot
UC ANR Publication 3438
D.R. Haviland, UC IPM and UC Cooperative Extension Kern County
E.T. Natwick (emeritus), UC Cooperative Extension Imperial County
J.K. Sidhu, UC Cooperative Extension Kern County
Acknowledgement for Contributions to Invertebrates
W.E. Chaney (emeritus), UC Cooperative Extension Monterey County
C.G. Summers (emeritus), Entomology, UC Davis and Kearney Agricultural Research and Extension Center, Parlier
