How to Manage Pests

UC Pest Management Guidelines

Walnut

False Chinch Bug

Scientific Name: Nysius raphanus

(Reviewed 7/17, updated 7/17)

In this Guideline:


Description of the Pest

The false chinch bug is an occasional pest of young walnut orchards. It hibernates as an adult and moves in late winter to preferred weeds, primarily mustard family weeds such as London rocket, shepherd's purse, and common peppergrass, where it stays to lay eggs in early spring. Nymphs are dull gray or brownish red and collect in great numbers on the host plants.

Damage

When weed hosts dry up in late spring, chinch bugs move into orchard trees where they may kill new foliage. This damage can occur within hours because the nymphs apparently inject a toxin while feeding. The leaves dry up and are covered with fecal spots. Damage may be substantial on trees that are 1 to 3 years old. Several generations are produced each year, but damage in orchards usually occurs only in spring.

Management

  • Where damage has occurred, control weed hosts in and adjacent to the orchard to prevent populations from developing in future years.
  • Begin checking weed hosts for false chinch bug in late February and early March, especially in years when moisture is abundant.
  • Mowing and discing cover crops before walnut trees begin to leaf out prevents false chinch bug development and migration.
  • If potentially harmful numbers are found on weeds or cover crops after walnut trees have leafed out, consider spraying the weeds or cover crop with a broad-spectrum insecticide, such as a a pyrethroid; avoid mowing or discing at this time to prevent migration to walnut foliage.
  • If nymphs are found on trees, apply a broad-spectrum insecticide, such as a pyrethroid.
Common name Amount to use** REI‡ PHI‡
(Example trade name)   (hours) (days)
Calculate impact of pesticide on air quality
Bee precaution pesticide ratings
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. Not all registered pesticides are listed. Always read the label of the product being used.
 
A. LAMBDA-CYHALOTHRIN*
  (Warrior II with Zeon) 1.28–2.56 fl oz 24 14
  MODE-OF-ACTION GROUP NUMBER1: 3A
  COMMENTS: Larvicide.
 
B. BIFENTHRIN*
  (Brigade WSB) 8–32 oz 12 7
  MODE-OF-ACTION GROUP NUMBER1: 3A
 
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 concentrate application, use the amount given in 80 to 100 gal water/acre, or lower if the label allows; for dilute application, amount is per 100 gal water to be applied in 300 to 500 gal water/acre, according to label.
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 these two intervals is the minimum time that must elapse before harvest may occur.
* Permit required from county agricultural commissioner for purchase or use.
Not recommended or not on label.

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Walnut
UC ANR Publication 3471

Insects and Mites

J. A. Grant, UC Cooperative Extension, San Joaquin County
J. K. Hasey, UC Cooperative Extension, Sutter, Yuba, and Colusa counties
W. W. Coates, UC Cooperative Extension, San Benito County
R. A. Van Steenwyk, Insect Biology, UC Berkeley
E. J. Symmes, UC IPM Program, Butte County
S. J. Seybold, Entomology, UC Davis (walnut twig beetle)
R. M. Bostock, Plant Pathology, UC Davis (walnut twig beetle)

Acknowledgment for contributions to Insects and Mites:
W. J. Bentley, UC IPM Program, Kearney Agricultural Research and Extension Center, Parlier (Emeritus)
L. C. Hendricks, UC Cooperative Extension, Merced County (Emeritus)
W. H. Olson, UC Cooperative Extension, Butte County (Emeritus)
C. Pickel, UC IPM Program, Sutter and Yuba counties (Emeritus)
G. S. Sibbett, UC Cooperative Extension, Tulare County (Emeritus)
D. Light, USDA, Albany, CA (Emeritus)(Codling Moth)

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