Question
scrub oak 1
This is 100 miles North of Sacramento, Ca. outside Red Bluff. There are at least 100 of these oak trees on my property. I have seen one other with theses symptoms.
The bottom 18 inches seems to be bulging out and the bark is separating (in some of that area) from the tree and crumbles easily. See pic
AnswerLooks like borer damage. I would spray the area of the trunk with an insecticide called Onyx or Merit--these insecticides will kill the insect under the bark. Borers attack trees under stress so I would also fertilize the tree with 10-10-10 fertilizer at the rate of 1 lb per inch of trunk diameter scattered around the tree and watered in good. Apply the fertilizer just before a rain storm and you will not need to water. Fertilize now and again in the spring.
Check with your local garden type store for these insecticides.
