Algorithm to find path with max sum of degrees in a tree structure
In a tree, there is exactly one path from the root to any vertex. So just do depth- or breadth-first search on the tree and label each vertex with the sum of the degrees on the path from the root to there. Then pick the leaf with the smallest value.

An optimization could be to use greedy best-first search, where you maintain a queue of vertices in increasing order of their weight (sum of degrees on the path from the root). The first leaf you find would then be guaranteed to be the one of minimal weight. This would reduce the number of vertices that you look at but it's possible that the additional overhead of maintaining the priority queue would negate that benefit.