How to Manage Pests

UC Pest Management Guidelines

Pistachio

Stink Bugs

Scientific names: Redshouldered stink bug: Thyanta pallidovirens
Green plant bug: Chlorochroa uhleri
Green stink bug: Acrosternum hilare

(Reviewed 2/07, updated 2/09)

In this Guideline:


DESCRIPTION OF THE PESTS

The redshouldered stink bug is somewhat triangular in shape and about 0.33 inch in length. It is predominantly green with a narrow red band across the shoulder; sometimes the band is absent. There is also a brown-colored phase, usually found in overwintering bugs. The green plant bug is dull to bright green and slightly larger (0.4–0.6 inch in length) and less common than the redshouldered stink bug. Green stink bug nymphs are a mixture of green, black, and orange. Adult green stink bugs are bright green with the entire lateral margin lined in yellow or orange.

Stink bugs often develop in weeds or field crops and move to pistachio, but they have also been found overwintering in orchards. Eggs of these stink bugs are laid in clusters, are barrel shaped, and have concentric dark rings at the top. Immature stages of these species have a wide range of color markings that are different from the adult.

Do not confuse pest stink bugs with the rough stink bug, Brochymena quadripustulata, a predator that is speckled white and gray and quite common in pistachio orchards throughout the year. Nymphs of Brochymena are colored red, white, and blue.

DAMAGE

Before shell hardening, stink bugs will cause damage similar to their smaller relatives (the plant bugs) by causing epicarp lesion and often nut drop. In most years, stink bug populations are not high enough to result in enough nut drop to cause crop loss because the tree will compensate for the damaged nuts during the natural nut drop period.

After shell hardening in July, stink bugs may cause kernel necrosis, which is identical to damage caused by leaffooted plant bugs. Kernel necrosis is not obvious externally, but inside the nut, the nutmeat is darkened, often develops a sunken necrotic area, and has an off-flavor. In July and August, feeding damage is indicated by an external, brown pinpoint mark; no white netting is visible. Although stink bugs can cause epicarp lesion early in the season, damaging populations have usually not been observed until late in the season.

Stink bugs are capable of transmitting some pistachio diseases, such as Stigmatomycosis and panicle and shoot blight, making control of these pests important.

MANAGEMENT

Stink bugs are primarily late season pests. During July and August, populations can become quite high. Although there is debate on the value of treating them, treatment will reduce kernel necrosis when populations are high. Stink bugs can be easily sampled with a beating tray. Time applications after the majority of eggs have hatched and nymphs are easily found.

Common name Amount/Acre** R.E.I.+ P.H.I.+
(trade name)   (hours) (days)

  Calculate impact of pesticide on air quality
The following materials are listed in order of usefulness in an IPM program, taking into account efficacy and impact on natural enemies and honey bees. When choosing a pesticide, also consider information relating to environmental impact. Not all registered pesticides are listed. Always read label of product being used.
 
A. PERMETHRIN*
  (Pounce) 3.2EC 8–16 oz 12 0
  (Ambush) 25WP 12.8–25.6 oz 12 0
  MODE OF ACTION GROUP NUMBER1: 3
  COMMENTS: Do not apply more than 0.8 lb a.i./acre/season for 25W formulation and 1.6 lb a.i./acre/season for 3.2 EC formulation. Highly toxic to honey bees.
 
B. BIFENTHRIN*
  (Brigade) WSB 8–32 oz 12 7
  MODE OF ACTION GROUP NUMBER1: 3
 
C. CYFLUTHRIN*
  (Baythroid XL) 2–2.4 fl oz 12 14
  MODE OF ACTION GROUP NUMBER1: 3
 
D. CARBARYL*
  (Sevin) 80S 3.75–6.25 lb 12 14
  (Sevin) 4F 3–5 qt 12 14
  (Sevin) XLR Plus 3–5 qt 12 14
  MODE OF ACTION GROUP NUMBER1: 1A
 
** Unless otherwise noted, apply with enough water to ensure adequate coverage.
+ Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (P.H.I.) 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). For additional information, see their Web site at http://www.irac-online.org/.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Pistachio
UC ANR Publication 3461

Insects and Mites

W. J. Bentley, Kearney Agricultural Center, Parlier
R. H. Beede, UC Cooperative Extension, Kings County
K. M. Daane, Biological Control, UC Berkeley/Kearney Agricultural Center, Parlier
D. R. Haviland, UC Cooperative Extension, Kern County
Acknowledgment for contributions to Insects and Mites:
R. E. Rice, Kearney Agricultural Center, Parlier

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