I have a 4 year old river birch with two trunks: the older, main trunk, and a newer and thinner 2nd trunk. The 2nd trunk appears to be sucking energy from the main trunk. Its leaves are lush and green, whereas the main trunk leaves are less dense, and yellowed. Is this a normal part of the development in a multi trunk tree? Or should I trim the 2nd trunk, in order to focus energy on the main trunk?

I'll be curious to see the responses. I have three different kinds of birches, and all are multi-trunked. As expected, the younger trunks are shorter than the leader, but the leaf arrangement seems pretty static. The ones I have are a river, paperbark, and Himalayan. I really like the look of a multi-trunk tree, and would hesitate to cut out the smaller one unless there is compelling reason to do so. It might be worth a call to an arborist, although I have no clue what they charge for diagnosing. I would not put too much faith in the cold call 'tree specialist' companies. I get 1-2 unsolicited visits per year, and this last time I took the young man around to a couple trees I'm having issues with, and he didn't even recognize the tree species, let alone have any insight. I think he was selling limbing, removal, and pruning. Period.

Are these trees ever grafted? The second, healthier trunk is coming directly off the roots.