What is the typical symptom of oak leaf blister on water oak?

Puckering is indeed the typical symptom of oak leaf blister on water oak. This condition is caused by a fungal infection, specifically from the genus Taphrina. When the fungus infects the leaves, it disrupts normal growth patterns, leading to characteristic puckered or blistered leaf surfaces. The abnormal growth results in a distortion of the leaf shape, which can appear raised or uneven.

While leaf drop, discoloration, and softening can occur with various plant stresses and diseases, they are not the hallmark symptoms of oak leaf blister. Leaf drop may occur later in the disease cycle or due to other factors, such as environmental stress. Discoloration can be a symptom of many foliar diseases but lacks the distinctive visual effect of puckering specific to oak leaf blister. Softening might suggest overwatering or root issues, which are unrelated to the specific fungal infection responsible for the blistering. Thus, the identification of puckering is crucial for recognizing oak leaf blister in water oaks.