By: Laura Miller
White peach scale has significant financial impact for commercial peach growing operations. White peach scale insects cause peach tree leaves to yellow and drop, decrease fruit production, and can lead to premature death of the tree.
For home gardeners and commercial growers alike, catching and combating the problem in the early stages of infestation is advantageous.
White peach scale insects (Pseudaulacaspis pentagona)are tiny armored bugs which consume sap and infest the bark, leaves, and fruitof trees such as peach,cherryand persimmon.These insects can inhabit over 100 species of plants and have worldwidedistribution.
These insects are very small, with adult females averaging3/64 to 3/32 of an inch (1 to 2.25 mm.). Mature females are white, cream, orgrayish in color and can be identified by the yellow or red spot that givesthese bugs the appearance of a fried egg. Adult females remain immobile, butyoung females spread to new areas before laying eggs. Fertilized femalesoverwinter on the trees.
The adult male of the species is smaller than the female,orange in color, and only lives about 24 hours. Wings give the males theability to fly and locate females via pheromones. Both male and female nymphsare smaller than the adult female. Depending upon the climate, more than onegeneration can be produced in a year.
Control of white peach scale is made difficult due to theheavy armor which protects these bugs. The best time to apply oil is earlyspring when the first generation hatches and begins migrating. Monitoring thiscrawler stage can be accomplished by wrapping infested limbs with double-sidedor electrical tape (sticky side out). Check the tape at least twice a week,using a magnifying glass to detect live bugs. Oilsprays are most effective against the immature insect pests.
Biological control can also be effective for white peachscale treatment in backyard trees and small home orchards. Predatorbugs which prey on white peach scale insects include ladybirdbeetles, lacewingsand parasiticwasps. Some species of predaceous thripsand mitesas well as gallmidges attack white peach scale.
Gardeners and commercial growers wishing to use chemicalsfor white peach scale treatment are advised to contact their localextension office for recommendations. Properly timed treatments are moreeffective and new products may be available.
Finally, proper orchard management reduces stress andpromotes healthier fruit trees This, in turn, helps trees overcome white peachscale damage.
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Factsheet | HGIC 2012 | Updated: Feb 23, 2021 | Print | Download (PDF)
Many armored scales are serious pests of ornamental shrubs, trees, groundcovers, and turfgrasses in South Carolina. Almost 40% of the Clemson Plant Problem Clinic sample submissions for home landscapes during 2012 and 2013 were scale insect pests, and of these, almost 90% of the species were the more difficult to control armored scales. Twenty-four different armored scales were identified on residential landscape plants. As winters have become warmer in recent years, additional insect pests may have extended their range more northward into South Carolina from Florida and coastal Georgia. More armored scale samples on ornamentals were submitted from the coastal areas of South Carolina than from the rest of the state, probably due to the milder winter weather there (see Table 1 for scale insects identified).
Table 1. Armored Scale Insects Identified on Landscape Plants by the Clemson University Plant Problem Clinic in 2012 & 2013
|Armored Scale||Host Plant|
|Holly Pit Scale||American Holly|
|Pine Needle Scale||Loblolly Pine|
|California Red Scale & False oleander Scale||Oleander|
|Tea Scale||Japanese Camellia|
|Tea Scale & Greedy Scale||Southern Magnolia|
|Greedy Scale||East Palatka Holly|
|Greedy Scale||Indian Hawthorn|
|White Peach Scale||Flowering Cherry|
|Citrus Snow Scale||Lemon, Tangerine & Grapefruit Trees|
|Obscure Scale||Flowering Dogwood|
|Gloomy Scale||Red Maple|
|False Oleander Scale||Southern Magnolia|
|Bermudagrass Scale||St. Augustinegrass|
|Pine Needle Scale||Shore Juniper|
|Palm Fiorinia Scale||Holly (evergreen)|
|Maskell Scale||Leyland Cypress|
|Greedy Scale||Common Boxwood|
|Unknown Armored Scale||Sabel Palmetto|
|Pine Needle Scale||Japanese Cryptomeria|
|Lesser Snow Scale||Cherry Laurel|
|Asian Cycad Scale||Sabal Palmetto|
|Elongate Hemlock Scale||Eastern Hemlock|
|Peony Scale||Japanese Holly|
|Cryptomeria Scale||Japanese Cryptomeria|
Some armored scales damage only branches, while others infest foliage or fruits. A severe infestation of armored scales may weaken or kill a tree or shrub.
Tea scale injury on camellia upper leaf surface
Clemson University – USDA Cooperative Extension Slide Series
Adult tea scales on lower camellia leaf surface.
Clemson University – USDA Cooperative Extension Slide Series
Scale adults are the most noticeable stage on plants, and these may be white, gray, or brown. Adult scales may be round, pear-shaped, or oyster-shell shaped but vary somewhat depending on the species. They secrete a waxy protective covering over their body, which makes control difficult. Some or all life stages of the scale may be found throughout the year (eggs, crawlers or immatures, nymphs, and adults).
Armored scales do not produce honeydew as do soft scales. The test (hard covering over the adult armored scales) will often have concentric rings or overlapping layers. Some soft scales may also have a hard covering present, but it will be smooth or with ridges but no overlapping layers. Flip an adult scale over, and if there is a separate soft body beneath the hard shell, it is an armored scale.
Identification of the scale is important as it may aid in better control. A sample of the infested plant material may be taken to the local Clemson Extension Service county office. From there, it will be sent to the Plant & Pest Diagnostic Clinic at Clemson University for accurate insect identification.
Euonymus scale on foliage.
John A. Weidhass, Virginia Tech University
Some scale insects are easier to manage than others. This is one of the tougher ones. This pest will have three generations each year. By the time the end of the season rolls around, your tree or shrub could be completely infested. This may even happen in areas of the plant where you’ve not noticed this pest before. White Prunicola Scale is often mis-identified and treatment ignored for a number of years. When this happens, there will be so much scale encrusting the branches that it can almost appear like someone had slathered it on with a brush.
This insect is built for survival. As they develop this crusty shell, it makes them easier to shelter themselves from not only natural predators but also makes it difficult to get insecticides to this pest. This makes it increasingly difficult for scale control. Managing White Prunicola Scale is possible, but it requires frequent inspection, periodic tree spraying, and a little extra effort to remove pests. Here’s our recommendations:
Timing is everything. Spray this pest in May, June, and August with a labeled insecticide. During the dormant season, have the tree spraying service apply horticultural oil to try to smother some of the overwintering adults.
Although it can be labor-intensive, using a soft-bristled brush and a bucket of soapy water can help to remove a large portion of these insects on branches. Doing this a couple times per season will drastically reduce populations and also allow for future insecticide applications to reach under that coating to this pest. You can also use a garden hose to blast off pests in some situations. Just use care not to damage the bark of the tree/shrub.
If possible, the best way to manage this pest would be to remove it and plant a species of plant that does not get attacked by White Prunicola Scale. Consult with a landscape designer that not only understands plant selection for aesthetics, but also knows the tree and shrub maintenance implications for the species that they select.