True southern live oaks (Quercus virginiana P. Mill) hold their leaves through winter and appear evergreen, while deciduous trees change colors each fall, delighting photographers and leaf peepers, before dropping them. With rakes in hands and aching backs, homeowners with deciduous trees might envy the neighbor with a southern live oak -- but they shouldn’t. The massive trees drop their leaves all at once every spring.
Leaves provide early signs that warn of the upcoming seasonal defoliation, better known as "leaf drop." This natural occurrence is not the result of disease. Symptoms include brown or black spots and yellowing with occasional brown discoloration along the veins. This occurs at the same time as nondescript flowers bloom on the tree. Both male and female flowers appear and require only two or three weeks to complete pollination, after which they disappear. Before old leaves fall, leaf buds form at the bases of the tiny stalks that attach the leaves to the stems.
Springtime leaf drop and dying off also occurs in other live oak trees. Southern live oak is considered the true live oak but many warm-climate oaks carry the label “live” – these are also considered evergreen and are different species from the true live oak. Examples include California scrub oak (Quercus dumosa), scrub oak (Quercus berberidifolia), and coast live oak (Quercus agrifolia Née). Each drops leaves in the spring to make room for new leaves.
Diseases can cause leaf fall. Oak wilt (Ceratocystis fagacearum), a highly contagious fungus, affects live oaks. Southern live oaks are not as susceptible as the plateau live oak (Quercus fusiformis) of central Texas, which has been seriously affected by oak wilt. Indicators of oak wilt appear most often in the summer – watch for yellowing of the leaves, especially on the veins, and a scorched or burned appearance on the leaf tips.
Traumatic losses due to disease can often be avoided if caught early, so remain attentive. If the leaves are beginning to fall in the spring, but the small leaf buds aren't appearing or your tree has several dead branches, consult with an arborist. Otherwise, you can be be pretty sure the leaves are dropping only to make way for spring's new growth.