Yellow leaves, leaf spots, and leaf drop are very common on yellow-poplar (tuliptree, Liriodendron tulipifera
) in the summer. This problem is caused by any of several fungal leaf spots, none of which are serious. See: Liriodendron tulipifera, Tuliptree
. The premature leaf drop is somewhat alarming but will not harm the overall health of the tree. New leaves will sprout over the rest of the summer and replace some of the fallen leaves, although the leaf drop will continue. Fungicide sprays are not needed and are impractical except on very young trees.