How to Manage Pests

UC Pest Management Guidelines

Apple

Stink Bugs

Scientific Names:
Consperse stink bug: Euschistus conspersus
Conchuela: Chlorochroa ligata
Redshouldered stink bug: Thyanta pallidovirens

(Reviewed 8/06, updated 3/09, pesticides updated 10/15)

In this Guideline:


DESCRIPTION OF THE PESTS

Stink bugs and other plant bugs occur in all of California, but only reach damaging numbers sporadically. Although they may differ in color and size, stink bugs have the same overall shield-shaped body. The consperse stink bug is the most common. Adult consperse stink bugs have gray brown to green bodies with yellow to orange legs and antennae that have darkened tips. The body and legs are covered with small black specks and the undersurface of the body varies from gray to green. Consperse stink bug eggs are laid in clusters on twigs and leaves. They are barrel-shaped, pearly white when first laid, turning pink before hatching. The conchuela is a large black stink bug with a reddish marginal border and a reddish spot in the middle of the back. Redshouldered plant bugs are green or brown stink bugs that may have a red line across the shoulder.

DAMAGE

Stink bugs damage the crop directly by feeding on fruit. Early season feeding results in dimples or irregularly depressed areas on mature fruit. If the feeding occurs after maturity there is little external evidence other than excrement, which appears as small, brown, tear-shaped drops. Internally, stink bug feeding produces white, pithy areas that turn brown when fruit is peeled. If the spots are the result of stink bug feeding, these pithy areas will be concentrated near the stem end of the fruit. If they resulted from lygus bug feeding, they may be located anywhere on the fruit surface. Adult stink bugs move from tree to tree and can puncture large numbers of fruit. If they are migrating into the orchard, fruits on trees in outside rows will show the most damage. Frequently, damage by these pests is limited to specific areas in the orchard. If the infestation is very heavy, however, the entire crop can be damaged.

MANAGEMENT

Infestations of stink bugs depend on the type of vegetation in and adjacent to the orchard. Most infestations occur in orchards with ground covers or adjacent to uncultivated areas; stink bugs move to ground covers in orchards when weeds in uncultivated areas dry. Consperse stink bug is rarely a pest in clean-cultivated orchards surrounded by cultivated lands, unless the land is planted in crops stink bugs favor: wheat, tomatoes, berries, alfalfa, or corn.

Cultural Control

Eliminate weed host plants listed above both within and adjacent to the orchard to minimize stink bug problems. Do not mow cover crops or weeds when stink bugs are present or they will move into the trees.

Organically Acceptable Methods

Cultural control is organically acceptable.

Monitoring and Treatment Decisions

Monitor for stink bugs in March or April by inspecting host plants located inside and along borders of sampling blocks. Spend about an hour checking the bases of plants for overwintered adult bugs. Favored host plants are mullein, mustard, and dock. If these are not present, bugs may be found on plantain, milkweed, mallow, morningglory, thistles, vetch, velvetgrass, breadgrass, bushberries, everlasting peas, and other broadleaf plants. If more than five bugs are found during the hour, spray the weeds with an insecticide immediately. Depending on the distribution of the bug population, a spot treatment may be adequate. If two to five bugs are found and bug damage has been experienced previously in the orchard, spraying the weeds might be advisable. If fewer than two bugs are found, resample in 7 to 10 days.

Sample for adults or damaged fruit in June and July. Take a 50-tray beating sample for each 20-acre block, taking most of the samples from border trees to locate bugs flying in from adjacent fields. If one or more bugs are collected, inspect fruit for feeding damage. Either examine fruit on the tree for the presence of bugs, excrement, or visible damage, or collect fruit from the lower half of the tree and peel it. If more than three fruits per half hour of inspection show feeding damage, spots of excrement, or active bugs, or there is one damaged fruit per 100 peeled, treatment of trees probably is required to avoid economic loss by end of harvest.

Common name Amount per acre REI‡ PHI‡
(Example trade name)   (hours) (days)

UPDATED: 10/15
Calculate impact of pesticide on air quality
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.
 
PINK BUD to BLOOM
Note: Apply as a thorough, drenching ground spray to cover crop; use 100 to 300 gal water/acre.
 
A. FENPROPATHRIN*
  (Danitol 2.4EC) 16–21.33 fl oz 24 14
  MODE-OF-ACTION GROUP NUMBER1: 3A
  COMMENTS: Begin applications when first pest activity is noticed. Use higher rate under severe insect pressure. Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
 
B. CLOTHIANIDIN
  (Belay) 4–6 fl oz 12 7
  MODE-OF-ACTION GROUP NUMBER1: 4A
  COMMENTS: Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
 
MAY or JUNE to PREHARVEST
Note: Apply to trees
 
A. FENPROPATHRIN*
  (Danitol 2.4EC) 16–21.33 fl oz 24 14
  MODE-OF-ACTION GROUP NUMBER1: 3A
  COMMENTS: Begin applications when first pest activity is noticed. Use higher rate under severe insect pressure. Disruptive of natural enemies. Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
 
B. CLOTHIANIDIN
  (Belay) 4–6 fl oz 12 7
  MODE-OF-ACTION GROUP NUMBER1: 4A
  COMMENTS: Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
 
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.
* 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).

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Apple
UC ANR Publication 3432

Insects and Mites

L. R. Wunderlich, UC Cooperative Extension, El Dorado County
J. L. Caprile, UC Cooperative Extension, Contra Costa County
P. M. Vossen, UC Cooperative Extension, Sonoma/Marin counties
L. G. Varela, UC IPM Program, Sonoma County
J. A. Grant, UC Cooperative Extension, San Joaquin County

Acknowledgment for contributions to Insects and Mites:
H. L. Andris, UC Cooperative Extension, Fresno County
W. J. Bentley, UC IPM Program, Kearney Agricultural Center, Parlier
W. W. Coates, UC Cooperative Extension, San Benito County
C. Pickel, UC IPM Program, Sutter/Yuba counties

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