10-10-10 will work fairly well as a tree fertilizer. If your soil is deficient in one of the macronutrients (N-P-K) you should select a fertilizer based on the soil or leaf analysis. Fertilize by poking holes about a foot deep around the drip line and pouring a half cup of fertilizer down each. You can broadcast the fertilizer around the dripline but the P will take a few years to work it' s way down to root level.

Dan O.