Columnar Oak Problems . This large genus consists of evergreen and. Crimson spire® will withstand high winds much better than softer wooded narrow trees. 17 Best images about Shade Trees on Pinterest Trees, London and Leaves from www.pinterest.com It is susceptible to powdery mildew in humid areas and planting in full sun with adequate airflow helps decrease this problem. It is therefore important to know to which group an oak belongs. The dark green leaves turn brown or yellow in autumn.