Question
QUESTION: A neighbor came into our yard and hammered copper nails into 3 large 14 yr old poplar trees.  He put somewhere between 25-40 copper ring shank nails around the base of each tree. (Yes, we sued him, Oregon takes it's trees serious and has a timber trespass law.) So far we have put over $3,000 back into saving these trees with deep root fertilization up to 4 times a year. This happen 2 and a half yrs ago. The trees look ok except for the fact that the leaves have black spots on them. Do you recommend we continue the deep root fertilization? We do not want to lose these trees as then this neighbor will look directly into our house and yard. But are we wasting money?

ANSWER: I would stop the fertilizer if the foliage is full. Leaf spot fungi make the leaves look off color but will not kill the tree. I would lay off the deep fertilizer and switch to fertilizing with 10-10-10 granular scattered around the tree and watered in good. Apply 1 lb pre inch of trunk diameter. If you apply the fertilizer just before a rain storm you will not need to water. I would apply early next spring. Sounds like it is recovering fine.  

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QUESTION: Thank you for the information regarding the poplars. Can I now ask about my fir trees?  The same neighbor had five fir trees illegally topped on our property while we were in escrow.  Two of these trees died, the remaining have struggled to live.  The tops started new growths which died.  We recently hired someone to cut the dead off of the tops of these trees.  Do they need a tar base covering on the newly cut area to protect them from further rot?

Answer
No the wound  paint will slow the healing process down. Fir trees have enough sap that the wound from the cut will seal over by itself. Cutting the tops out of conifers can be tricky. the top leader is the meristem and the growing part of a tree when it is cut off a side branch will have to take over for the tree to survive. This will leave a bend in the trunk where the top was cut. Sometimes the firs will survive from topping but other times they will die.