the willow oak is an excellent choice as a shade tree. It thrives in moist, well-drained, acidic soil and full sun. The willow oak will tolerate pollution and drought and is considered a trouble-free tree as long as soil pH is acidic. Willow oak has a fibrous root system and is therefore easy to transplant. It has no serious disease or insect problems. As little as 1 inch of fill soil can kill an oak.