Thank you for the question. The recent cold weather may be the reason the tree is slow to leaf out. We advise a wait and see approach for a few months. We certainly hope your tree perks up with warm weather and does well. While you are observing the tree, think back to how the tree was planted and the care it was given up to now. Failure to thrive is often a variety of factors and the main focus of proper planting and tree care in the first few years is to encourage root establishment of the tree. A common reason new trees fail is a problem with one of these cultural factors. Here are links to excellent publications on how to properly plant and care for new trees in the landscape:
Diagnosing from photos is difficult but judging from how the tree goes into the ground (like a telephone pole) may be a clue to the fact that it was planted too deeply. There should be a slight flare, even on a new tree, as it goes into the ground. As to the question of fertilization, if you fertilize your lawn turfgrass, the tree is getting plenty. If you want, you could submit a soil sample and fertilize according to the report. Here is how to do it: http://soiltest.cfans.umn.edu/
Trees can appear to do well for a year or two after planting while living off of stored food supplies. When these supplies are exhausted and there is a problem with the root system, the tree can't replace energy and dwindles and dies. Fertilizer won't "fix" the problem.
Thank you for contacting Extension.