פירוש על עבודה זרה 100:5

Ravina first needs to figure out what the difficulty is. If we think the difficulty is in figuring out why one can treat the tree on the Sabbatical year but not on the festival, this is not a difficulty. The Torah prohibits certain types of agricultural work but there is no prohibition of exertion. Taking care of the tree is not one of those forbidden labors. But on the festival it is prohibited to do all sorts of activities that require exertion. This would include taking care of the tree. So this should not be a difficulty at all.