If you have a Cherry Tree, Cherry Laurel, Red Twig Dogwood, Privet, Lilac, or Euonymus in your landscaping, you should really learn what White Prunicola Scale is. There are all sorts of scale insects that feed on landscape trees and shrubs here in our area. These pests typically appear in small numbers and reproduce rapidly until there are so many on a host plant that it becomes easier to spot on their branches and twigs. As this pest feeds on the plants vital nutrients, growth will be stunted and plants will eventually decline to the point where owner have to remove them.
Some scale insects are easier to manage than others. This is one of the tougher ones. This pest will have three generations each year, so by the time the end of the season rolls around, your tree or shrub could be completely infested in areas you’ve not noticed this pest before. Miss identifying and treating this pest for a number of years, and there can be so much scale encrusting the branches that it can almost appear like someone had slathered it on with a brush.
These insects are 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:
Get a Tree Service to Spray your Trees & Shrubs: 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.
Physically Remove Scale: 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.
Replace Infected Plants: 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.
If you have plants that are minimally affected by scale, begin with trying to manage pest populations. A company with Certified Arborists can help you to assess if that is a good measure or if you should consider replacing plants.