White Prunicola Scale

White Prunicola Scale | Image Credit: Brian Kunkel, University of Delaware, Bugwood.org

If you’ve been noticing white patches on your trees and shrubs it could be a case of White Prunicola Scale (Pseudaulacaspis prunicola). White Prunicola Scale is an armored scale, thought to have originated in China or Japan, that feeds on the fluids/sap in trees and shrubs. If left untreated this insect infestation can severely harm or even kill your tree.

White Prunicola Scale tends to first appear in small numbers then rapidly increase until you can easily spot the telltale white patches on the tree’s trunk and limbs. Since this insect feeds on the plants vital nutrients, your plant’s growth will be stunted and overall health will continue to decline.

Although White Prunicola Scale is easy to recognize it is often confused with White Peach Scale (Pseudaulacaspis pentagona), which we’ve discussed before

Susceptible Trees:

White Prunicola Scale is most commonly found on trees in the genus Prunus including Japanese flowering cherry and Cherry Laurel. This insect is also commonly found on Privet, Lilac, Euonymus, Willow, Red Twig Dogwood, and Catalpa. 

Symptoms & Signs Of White Prunicola Scale:

  • White coating on trucks and limbs
  • Yellowing of leaves
  • Premature leaf drop
  • Dieback
  • Cracked bark
scale covering female-eggs coming out from underneath | Photo Credit: Brian Kunkel, University of Delaware, Bugwood.org

Treatments For White Prunicola Scale:

White Prunicola Scale can be difficult to control; however, with a combination of overall health improvements and targeted scale treatments, our Arborists can help stop them from destroying your trees. Depending on the time of year and level of infestation, your Arborist may recommend a variety of treatments including the ones below. Just remember, it’s best to move fast when you see signs of infestation. 

PREVENTION: Scale, like most insects, is more likely to feed on stressed trees. Maintaining the health and vigor of your trees can help protect against scale infestation.  You can maintain the health of your tree through routine pruning, bio-stimulant applications, and seasonal sprays.

Pruning & Washing: If the population isn’t too high, our Certified Arborists may be able to remove White Prunicola Scale by washing the bark and pruning out the infestation. However, it’s likely that to gain proper control you tree will require the treatments below. 

Horticultural Oil: White Prunicola Scale can be prevented from taking hold by applying horticultural oil during the dormant season and early spring. This will control the insect in its early stages (nymphs). 

White Prunicola Treatment

Insecticide: If caught during Spring or early Summer your Arborist may recommend using systemic insecticides to control the problem by targeting/feeding adults and nymphs. If caught later in the summer once symptoms are more visible the arborist may recommend using traditional bark spray insecticides.

If you think your tree is showing signs of White Prunicola Scale or if your tree had this insect last year, we can help. Give us a call at 703-573-3029 or book online as soon as possible to schedule a consultation with one of our Certified Arborists. The sooner White Prunicola Scale is caught the easier it is to treat, so don’t delay!

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