Q: Now that my oak tree is dormant, can I spray 2,4-D on the mistletoe while being careful not to wet other plants under the tree? The mistletoe is high up on the tree but I may be able to attach a sprayer at the end of a bamboo cane and turn the water on when the sprayer is near the mistletoe.
A: This is not a good idea at all. Since mistletoe is a parasite, the little leafy green branches you see extend their roots into the branch of the host tree.
If you spray herbicide on the mistletoe it will get into the tree branch and will harm that branch.
If you can reach the mistletoe to prune it you could paint the stubs with pruning paint or wrap the branch with black plastic.
But if the mistletoe is high in the tree that would be impossible.