Description of the Pest
The adult moth is gray with a wing expanse of 0.75 to 1 inch (19–25 mm) and brown and black markings on the wings. Adult females lay eggs near where callous tissue has developed, such as at pruning wounds, crown galls, or scaffold crotches. Larvae bore into the tree to feed on vascular tissue. Mature caterpillars are dusky white or pinkish and are about 1 inch long. American plum borer overwinters in a protective cocoon spun in a sheltered location on the tree; pupation takes place in spring. There are three to four generations each year.
Damage
Larvae attack soft, spongy, calluslike tissue, which occurs at graft unions, tree wounds, and in olive knots. They can continue to feed into normal tissue, girdling limbs, which can cause small branches to break. Gummy frass and liquid exudate may occur around injured wood.
Management
Monitor trees in spring and summer for frass and gum pockets. The borer can be detected by brownish frass and webbing at feeding sites. If larvae are present, remove and destroy infested wood if possible. If wood cannot be removed, spray trees with a hand held sprayer from one foot above the scaffold crotch to one foot below, two to three times during the growing season. The first application should be mid- to late April and subsequent applications at 6-week intervals. Efficacy is improved if the trunk is painted immediately following a trunk spray with a latex paint to protect against sunburn. The paint helps to preserve the insecticide and give protection over a longer period of time.
| Common name | Amount to use** | 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 SL) | 5.0–7.5 qt | 12 | 14 | ||
| (Sevin XLR Plus) | 2 qt | 72 | 14 | ||
| MODE-OF-ACTION GROUP NUMBER1: 1A | |||||
| COMMENTS: Do not exceed 15 qt carbaryl SL/acre per crop or 15 qt carbaryl XLR Plus/acre per crop per year. To protect honeybees, apply only during late evening, night, or early morning when bees are not present. | |||||
| ** | Amounts per 100 gal water (except where otherwise stated), using 400-500 gal solution per acre. |
| ‡ | 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 R.E.I. 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). |