Tulip trees (Liriodendron tulipifera) are deciduous trees that can grow to over 100 feet tall. Their leaves turn brilliant yellow to golden yellow in the fall, then drop off for the winter. Leaves can sometimes fall off in the summer though, for a couple different reasons.
Tulip trees are sensitive to summer drought and are considered an indicator species. When the tree does not get enough water, leaves in the interior will begin to yellow and drop off in late July or early August.
Anthracnose disease can cause trees to lose leaves. It first appears as dead areas on the leaf that can eventually merge together, killing the leaf. Leaf loss can occur in badly infected trees. A new crop of leaves may appear if leaf loss happens from spring to early summer.
To prevent summer leaf loss, water tulip trees well during dry periods. Anthracnose can be controlled by raking up and destroying infected leaves and keeping foliage dry by avoiding overhead watering and ensuring good air circulation around the tree.