[MBAtarga]

Over fertilization will kill a healthy tree.
Google search - For all trees and shrubs:
If needed, the best time to fertilize is late April or early May, or late fall once plants are dormant. The recommended fertilizer should be spread evenly across the soil surface. The amount of actual nitrogen applied should be 3 pounds (lbs) per 1,000 square feet.

Do not assume trees damaged during storms will benefit from a fertilizer application. In most cases they will not, and the fertilizer will inhibit the tree's ability to recover. ... Trees generally don't need more than 1 pound of actual nitrogen per 1,000 square feet of root area per year.