Hi, 

You can review our soft scale page to see if you can identify it. Cottony Camelia scale (the first listed on that link)  is common on holly. We would have to see a photo of the scale to be able to recommend further guidance. You can attach pictures to a response. 

Since the trees are well over your head though, you may want to consider hiring a certified pesticide applicator if the scale population seems large enough  to treat the trees. They will have the equipment, knowledge, and protective gear needed to reach into the entire canopy. You can search for a certified arborist company  at https://www.treesaregood.org/findanarborist. 

Emily

Yes it is best to stay ahead of it if you can. 

you can but you want to make sure to target mostly the nymph stage meaning when the crawlers emerges from the eggs around mid June to smother them, the adults will have the protective coating so hort. oil won't really be effective. You can do multiple applications per the label directions over the course of the summer before the nymphs progress into adults. 

 Make sure that the hort. oil is the proper strength as well and not at a rate for dormant oil which could burn the leaves in higher temperatures. 

Since they are on the underside of the leaves it can be difficult to reach them all and why it is typically easier to hire a professional to reach the entire tree so it can be most effective.

Hi Serap, 

The file type you submitted can't be opened on this program. We can accept jpeg, png, gif, and you can also attach a pdf or google drive link. 

Emily

That does look like Cottony Camelia Scale with out the formation of the ovisac that makes it white. 

You can try to pick off what you can see but they are well camouflaged at this state and may be up higher in the tree. 

The spraying and timing mentioned previously should help.