Because they are not coded to decay the way normal leaves do, the nether wart blocks used as leaves for the new nether trees are almost impossible to get rid of. Each tree has quite a lot of wart blocks, and because nether wart blocks have no designated tool (axe, pickaxe, shovel), it takes several minutes of tedious work to clear an area of trees. A simple decay=0/1 toggle for player placed vs. tree generated nether wart blocks, along with a reduction in the time it takes to mine them, would solve this problem completely.