Agriculture: Dry Beans Pest Management Guidelines

Cucumber Beetles

Description of the Pest

Cucumber beetles are frequently abundant in bean fields, but damage is usually insignificant. The western spotted cucumber beetle is yellowish-green, 0.25 inch (6 mm) long, and has eleven black spots on its wing covers. The whitish wormlike larvae feed on roots of corn, legumes, and grasses. When the surrounding areas dry up, the adults will swarm into the bean field.

A close relative, the western striped cucumber beetle is yellowish and has three black lines down its back. The larvae live in the soil where they feed on roots, while the adults are foliage and flower feeders. For further assistance with identification, see A Field Key to the Cucumber Beetle Species Found in California.

Damage

Although western cucumber beetles feed on all ages of dry bean plants, they cause the most damage to young plants, resulting in seedling stand losses. On mature plants, they tend to feed primarily on the older foliage and therefore seldom cause economic damage to established dry beans.

Management

Specific treatment thresholds have not been established for cucumber beetles. Start inspecting plants for cucumber beetle damage when the crop emerges. Continue monitoring through the vegetative growth and flower bud to bloom stage. If there are damaging numbers during the early-season with excessive foliage loss, an insecticide application may be warranted to prevent crop loss. Mid- to late season infestations are not associated with crop loss and do not require insecticide application.

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 XLR Plus) 0.5–1 qt 12 21
  MODE-OF-ACTION GROUP NUMBER 1: 1A
 
B. MALATHION
  (Fyfanon ULV AG) 8 fl oz 12 1
  MODE-OF-ACTION GROUP NUMBER 1: 1B
  COMMENTS: Do not graze livestock in treated areas or harvest vines for forage or hay.
 
C. BIFENTHRIN/IMIDACLOPRID
  (Brigadier) 5.6 fl oz 12 14
  MODE-OF-ACTION GROUP NUMBER 1: 3A/4A
 
D. BIFENTHRIN
  (Bifenture EC) 2.1–6.4 fl oz 12 14
  MODE-OF-ACTION GROUP NUMBER 1: 3A
 
E. CYFLUTHRIN
  (Baythroid XL) 2.4–3.2 fl oz 12 7
  MODE-OF-ACTION GROUP NUMBER 1: 3A
 
F. LAMBDA-CYHALOTHRIN
  (Warrior II with Zeon) 1.28–1.92 fl oz 24 21
  MODE-OF-ACTION GROUP NUMBER 1: 3A
  COMMENTS: Do not graze livestock in treated areas or harvest vines for forage or hay.
 
G. BIFENTHRIN/ZETA-CYPERMETHRIN
  (Hero EW) 4.5–11.2 oz 12 21
  MODE-OF-ACTION GROUP NUMBER 1: 3A/3A
 
SEED TREATMENTS
 
A. THIAMETHOXAM
  (Cruiser 5FS) 1.28 fl oz per 100 lbs seed NA NA
  MODE-OF-ACTION GROUP NUMBER 1: 4A
* Permit required from county agricultural commissioner for purchase or use.
** Mix with sufficient water to obtain full coverage.
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.
1 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; pesticides with a 1B group number should be alternated with pesticides that have a group number other than 1B. Mode-of-action group numbers are assigned by IRAC (Insecticide Resistance Action Committee).
Text Updated: 06/18
Treatment Table Updated: 06/18