I have a fair amount of poison ivy growing on one part of my fence.  Now that spring is here, it's just barely started to grow again, and buds that will turn into the dreaded leaves have began to appear (note the slightly lighter colored growth along parts of the darker core of the plant):

[![enter image description here][1]][1]

Can I go ahead and start spraying it with poison ivy killer now, or is it only really effective once the leaves have fully appeared first?

Or perhaps is it better to simply use poison ivy spray directly where the vine originates from the ground, meaning I can start now and do it repeatedly?

  [1]: https://i.sstatic.net/eoHNP.jpg