Description of the Pest
Stink bugs and otherplant bugs occur throughout California, but only reach damaging numberssporadically. Although they may differ in color and size, stink bugs all havethe same overall shield-shaped body. The consperse stinkbug is the most commonly found inall pear districts.
Adult conspersestink bugs have gray brown to green bodies with yellow to orange legs, andantennae that have darkened tips. The body and legs are covered with smallblack specks and the undersurface of the body varies from gray to green. Conspersestink bug eggs arebarrel-shaped, pearly white when first laid, turning pink before hatching, andlaid in clusters on twigs and leaves. The conchuela is a large, grayish blackstink bug with a reddish marginal border and a reddish spot in the middle ofthe back that distinguishes it from the bordered plant bug. Redshoulderedstink bugs aregreen or brown and may have a red line across the shoulder. Leaffootedplant bug adults are about 0.75 inch long, yellowish brown and have yellow bands acrossthe middle of the back. The back is flat and the hind legs have distinctive,leaflike enlargements.
Damage
Stink bugs damage the crop directly by feedingon fruit. Early season feeding results in dimples or irregularly depressedareas on mature fruit. If the feeding occurs after maturity, there is littleexternal evidence other than excrement, which appears as small, brown,tear-shaped drops. Internally, stink bug feeding produces white, pithyareas that turn brown when fruit ispeeled. If the spots are the result of stink bug feeding, these pithy areaswill be concentrated near the stem end of the fruit. If they resulted from lygusbug feeding, theymay be located anywhere on the fruit surface. In pears, these pithy areas aretoo deep to be removed by ordinary peeling practices and the fruit isunsuitable for canning or fresh market.
Adult stink bugsmove from tree to tree and can puncture large numbers of fruit. If they aremigrating into the orchard, fruits on trees in outside rows will show the mostdamage. Frequently, damage by these pests is limited to specific areas in theorchard.
Management
Stink bugs and plantbugs may become more important pests in orchards where mating disruption isused for codling moth control. Infestations of stink bugs depend on the type ofvegetation in and adjacent to the orchard. Most infestations occur in orchardswith ground covers or adjacent to uncultivated areas; stink bugs move to groundcovers in orchards when weeds in uncultivated areas dry. Consperse stink bug israrely 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. Monitor weeds in spring and trees in early summer todetermine need for treatment.
Cultural Control
Reduce weed hostplants, listed below, both within and adjacent to the orchard to minimize stinkbug problems.
Organically Acceptable Methods
Biological andcultural controls are organically acceptable methods of controlling thesepests.
Monitoring and Treatment Decisions
If stink bugs areobserved, monitor during the cluster stage in March or April byinspecting 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, beardgrass, bush berries,everlasting peas, and other broadleaf plants.
If more than fivestink bugs are found during the hour, apply a ground spray to the weeds immediately.Depending on the distribution of the bug population, a spot treatment may beadequate. If two to five bugs are found, and if bug damage has been experiencedpreviously in the orchard, a ground spray might be advisable. If fewer than twobugs are found, resample in 7 to 10 days.
Consperse stink bugscan also be monitored beginning in early April with double cone traps baitedwith an aggregation pheromone. Place traps just outside the edges of theorchard to determine if adults are migrating into the orchard. (For moreinformation, see PHEROMONE TRAPS.) Cut fruit is attractive forfeeding. Beginning in May, place cut fruit at the edge of the orchard next tounmanaged or alternate hosts. Check and replace weekly.
In June and earlyJuly spend about 30 minutes sampling for adults starting from the edge of theorchard and working your way inward. Also inspect fruit for feeding damage.Examine fruit on the tree for the presence of bugs, excrement, or visibledamage. To verify that damage is caused by stink bugs, peel the fruit. If morethan three fruits per half-hour of inspection show feeding damage, spots ofexcrement, or active bugs, treatment probably is required to avoid economicloss by end of harvest. Be sure to take into account preharvest intervals whenchoosing the treatment material, and apply this treatment to the trees. (Forinformation on sampling stink bugs in conjunction with other pests at thistime, see SAMPLING DURING FRUIT DEVELOPMENT.)
Harvest Fruit Sample
At harvest, assessprogram by monitoring fruit in the bins for stink bug and other plant bugdamage. Sample 200 fruit per bin from 5 bins per orchard (or 20-acre block inlarge orchards). (For more information regarding this sample, see HARVESTFRUIT SAMPLE.)
| Common name | Amount to use** | REI‡ | PHI‡ | ||
|---|---|---|---|---|---|
| (Example trade name) | (conc.) | (dilute) | (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. | |||||
| FINGER BUD to BLOOM | |||||
| Note: Apply a thorough, drenching ground spray when adults begin activity. Dilution rates will vary from 100 to 300 gal/acre. | |||||
| A. | DIMETHOATE | Label rates | see label | 28 | |
| MODE OF ACTION GROUP NUMBER1: 1B | |||||
| COMMENTS: Dimethoate can be applied with oil. Do not apply to blooming plants, including fruit trees and broadleaf weeds. Mow weeds before application. Not allowable by some processors. | |||||
| JUNE to PREHARVEST | |||||
| Note: Treatment is applied to trees. | |||||
| A. | FENPROPATHRIN* | ||||
| (Danitol 2.4EC) | 16–21.33 fl oz | 4–5.3325 fl oz | 24 | 14 | |
| MODE OF ACTION GROUP NUMBER1: 3A | |||||
| COMMENTS: Harmful to beneficial insects and mites; will suppress spider mites. Do not apply to blooming plants, including fruit trees and broadleaf weeds. | |||||
| B. | LAMBDA-CYHALOTHRIN* | ||||
| (Warrior with Zeon) | 2.56–5.12 fl oz | — | 24 | 21 | |
| MODE OF ACTION GROUP NUMBER1: 3A | |||||
| COMMENTS: Harmful to beneficial insects and mites; will suppress spider mites. May cause outbreaks of pear rust mite. Do not apply to blooming plants, including fruit trees and broadleaf weeds. | |||||
| ** | Dilute rate is the rate per 100 gal water; use 400 gal solution/acre. Apply concentrate in 80–100 gal water/acre, or less if the label allows. |
| ‡ | 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 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). |
| * | Permit required from county agricultural commissioner for purchase or use. |
| — | Not recommended or not on label. |
