Oak tree problem

[Astro]

Hope you can help. I'm not knowledgeable on trees and can find no information on this problem.

 

I have an oak tree in a large pot that was planted by my son when he was a infant, some 25 years ago. It has recently developed a large number of small reddish coloured nodules on its bark, which can be brushed off. I can find no information on this and would appreciate if you could identify this problem and suggest what I should do. Please find attached 2 photos of the tree.

 

In appreciation, John

[Lucan]

Looks like scale insects

[treequip]

Yup, that's scale insect, and PLEASE get a bigger container

[KTSmith]

Although famously not an insect expert, I'll hazard to suggest that the pest is one of the Lecanium "soft scales". Usually, predation by native biocontrol agents (lacewings, ladybugs) keeps the numbers down, but you've got a pretty strong infestation going. Chemical treatments are available, but are usually applied earlier in the season when the immature crawlers are up and about. Often the adults (what you have pictured) have laid their eggs and are dead and brown by the time they are noticed. I don't know what is labeled for use in the UK for tree scales, but check at your local supply store.

Also, the picture does demonstrate how to dwarf an oak by keeping the root system constrained. Perhaps that was the intention!

[Astro]

Many thanks for your help on this matter. I know what I'm dealing with now. Interestingly in KTSmith reply regarding controlled by biocontrol agents I've seen very few ladybirds this year whilst in previous years there has been a lot. In appreciation, John