Scale on Cherry tree

Question: I have a young cherry tree that produced a number of cherries this spring and appeared in good health. Earlier today, I was viewing my trees with an arborist from a Tree cutting/management system and frealized my tree was coivered in a white coating. He told me it was scale, and that he was not certain of the best treatment, though he did think you folks might be able to assist.

Below are two pictures and I will appraoach treating this as soon as I hear from you.

Many thanks - Nell

responder: An Ask Extension Expert Replied August 20, 2024, 5:04 PM EDT
response: Hello Nell, Yes, this is either white peach scale or white prunicola scale, two closely related species. The infestation seems pretty extensive, so treatment may take a couple years. If left unchecked this could kill branches and weaken the whole tree. The primary control point for scale insects is before bud break when horticultural oils are applied to the tree. Look for oils labeled for scale insects on cherries. The other times of year when these can be controlled are during the "crawler stages" when the scale larvae emerge. and are susceptible to insecticides. The University of Minnesota Extension has a good guide on scale insects, including a guide on checking for crawlers. There is likely to be another generation of crawlers emerging in the next couple weeks, so you should start checking for them soon (see the Minnesota guide) and apply a low impact insecticide labeled for use on scale crawlers. Applying when crawlers are not present will not do anything for you. If the combination of a fall crawler spray, a late winter dormant oil spray, and possibly a spring crawler spray does not suppress the population you may need to get an arborist with a pesticide license to spray something more effective during a subsequent spray window.

responder: The Question Asker Replied August 20, 2024, 5:32 PM EDT
response: Thank you for your response. I am finding the link to be a bit challenging for me to understand.  Can you identify for me - is my picture of the egg cycle?Also, is it worthwhile to use a paper towel with rubbing alcohol to remove this white scaling from the tree, as was suggested in a google search?Thank you - NellOn Tue, Aug 20, 2024 at 5:04 PM Ask Extension <<personal data hidden>> wrote:

responder: An Ask Extension Expert Replied August 20, 2024, 6:05 PM EDT
response: Hello Nell, Yes, females lay eggs underneath the hard shells they form on the tree where the eggs are protected while they hatch. Using rubbing alcohol to remove the scales won't hurt the tree and may help reduce the population, but they are probably very difficult to remove. You may have more luck with a scraping instrument and scraping the scales into a bag of rubbing alcohol. On a large commercial scale that wouldn't be practical, but for one or two trees in a back yard that could partially solve the problem. For particularly heavily infested branches pruning may be more effective. Either way you should still plan to use a dormant oil spray as this will be the most effective way to prevent further infections.

responder: The Question Asker Replied August 21, 2024, 8:00 AM EDT
response: Thank you so much! On Tue, Aug 20, 2024 at 6:05 PM Ask Extension <<personal data hidden>> wrote: