How to Manage Pests
UC Pest Management Guidelines
Peach
Shothole Borer
Scientific name: Scolytus rugulosus
(Reviewed 3/06,
updated 3/06)
In this Guideline:
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Shothole borers are tiny brown or black beetles;
their white legless grubs mine the tree's cambium layer (sapwood). Adult
females bore tiny holes in the bark and lay eggs in
the cambium layer of the tree. When the eggs hatch, young larvae feed and excavate secondary
galleries at right angles to the egg gallery. The outline of the gallery system resembles a centipede. There are from one to three generations each year.
Normally a number of shothole borer adults invade a tree at the same
time. Healthy trees exude resin,
which usually kills the insects. If the tree has injured or weakened areas,
this resin buildup does not develop and the invasion is successful. Ultimately
larvae can girdle the tree, causing tree or branch death.
Maintaining healthy trees and preventing sunburn are the keys to
preventing damage by shotholeborer. Painting the trees with white wash or a 50:50
mixture of white interior latex paint and water will help prevent sunburn and
possibly inhibit egg laying. Avoid pruning during summer, and prune trees so
that scaffolds are shaded to prevent sunburn. Remove horizontal scaffolds when
pruning/thinning young trees.
Protect newly planted or
newly grafted trees from sunburn by painting the trunk and
graft with white interior latex paint or using tree wrappers around the trunk.
If paint is used, be sure to mix it with water; undiluted latex paint can kill
young trees. Thin the latex paint to a mixture of one-half water and one-half
latex paint and paint the trunk from 2 inches below ground level to 2 feet
above.
Prune to eliminate areas
in older trees infested with shothole borer. Remove severely infested trees.
Burn or remove all infested wood from the orchard before the growing season
starts. Do not leave pruned limbs or stumps (healthy or infested) near orchards
(for example, in woodpiles) as populations can emerge from these materials
before they dry out, and beetles will then migrate into orchards. There are no
insecticide treatments recommended for this insect.
| Common name |
Amount to Use |
| (trade name) |
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| A. |
WHITE INTERIOR LATEX PAINT#
| 50% paint and water mixture |
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COMMENTS:
Paint trees at time of planting. Be sure paint extends below ground level.
This treatment will prevent sunburn, which can reduce attack by shothole borer. |
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![[UC Peer Reviewed]](/IMAGES/logo-ucpeerreviewed.jpg)
UC IPM Pest Management Guidelines: Peach
UC ANR Publication 3454
Insects and Mites
C. Pickel, UC IPM Program, Sutter/Yuba counties
W. J. Bentley, UC IPM Program, Kearney Agricultural Center, Parlier
J. K. Hasey, UC Cooperative Extension, Sutter/Yuba counties
K. R. Day, UC Cooperative Extension, Tulare Co.
Acknowledgment for contributions to the insects and mites section:
R. E. Rice, Kearney Agricultural Center, Parlier
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