Does my tree have a disease or infestation?

Asked March 20, 2020, 4:23 PM EDT

I noticed all branches on a tree in the front yard covered in a black sooty appearance with numerous nodules clinging along many branches. Is this a disease or insects? I cut one branch and noticed the cambium ring is still green even with all the sooty surface coloring and nodules (see photo). All new bud growth appears dead and shriveled. What is this? Douglas Franke

New Castle County Delaware

1 Response

Dear Douglas,
From the photo provided, it looks like you might have lecanium scale.

You didn’t mention the type of tree this is. This would be helpful in the diagnosis. You usually find scale on stressed trees.

Soft Scales In general, soft scales are larger and more convex than armored scales. Many resemble miniature tortoise shells. Soft Scales usually cover themselves with wax, but they lack the detachable protective cover for which armored scales are named. Most soft scales overwinter as immature, fertilized females. In spring they resume feeding, mature, and lay eggs. These hatch into tiny crawlers. After locating suitable feeding sites, crawlers settle and begin feeding. Some species lose their legs once they've settled, but others retain them and are able to crawl short distances to find suitable overwintering sites in the fall. Treatments made during the crawler stage of their life cycle is usually most effective.

Here are several fact sheets that should be helpful:

if you get the scale infestation under control the sooty mold will eventually disappear. If you have not done a soil test in the last three years, this might helpful for assure good tree growth.
Best regards,