I mean, if so we should be making it rain as much as possible.
My theory together with Ungod is that the tree is burning, and that constitutes its "life". (See also the clue on "the blooming of bob" for more about the alive-ness of the tree.)
For lack of foliage (in contrast to the trees in MB) it simply burns at its core/s, similar to the necrovion trees except straight. (this actual puts it in a unique position to "ensure the fruit")
Rain would kill it, thus ending its core-burning pain, but the pain is actually worthwhile for him if he still might bloom.
You can actually see some of the smoke from the branches if you look closely.