The late season freeze-hail-freeze has caused trees to struggle. As trees leaf out in the spring, late freezes can severely damage or kill buds and new leaves. This will cause a tree to use stored energy to re-leaf so this can result in a slower second try, or fewer/sparser leaves.

It's a good sign the branches are flexible and not brittle. You can also take a sharp knife or use a fingernail to gently scrape a small piece of bark off of several small twigs. If the exposed twig is green, the branch is still alive. It appears in the photo that the tree has many buds on it, some quite large perhaps nearing leaf out. Take a close look at the buds to see if they are green (alive) or black (dead).

Take a wait-and-see approach for the tree. Make sure the tree receives adequate moisture and look for growth. If your lawn is fertilized with Nitrogen-Phosphorus-Potassium (N-P-K), your tree does not need any additional fertilization of N-P-K.

Kelp is considered an organic fertilizer. It does not contain the major nutrients of N-P-K, but rather it is sometimes used to provide micronutrients: trace minerals, amino acids, vitamins and growth hormones that stimulates plant cell division. Wait to see if your tree leafs out before an application. There is more information on kelp at this link:

http://www.ext.colostate.edu/mg/gardennotes/234.pdf