Alfalfa, nettle, and comfrey have pretty solid growth promoting and health enhancing qualities
S. Lowe, yes by all means, only that they seem to be useful in other moments or stages of the orchard year.
M. Phillips suggests to spray neem oil + liquid fish + compost tea when half of the tree leaves are on the ground, in order to smother fungal spores that attach to decomposing leaves and stimulate the activity of beneficial bacteria and deter other harmful "beasts" that dwell in the tree trunk. Each type of spray has a specific function or more than one.