Not all bur oaks get BOB. Symptoms of BOB are first seen in mid-summer, but the most obvious symptoms are not apparent until late summer. BOB initially kills segments of leaf veins, and then it kills wedge-shaped segments of leaves between leaf veins. Disease starts in the lower canopy. BOB may also cause rapid leaf loss, initially in the lower and middle canopies. In severe cases, all but the outermost leaves around the canopy will be killed. BOB might cause minor dieback, but it will not kill major limbs. Other problems such as Armillaria root disease, twolined chestnut borer, and oak wilt kill major limbs.
Wedge-shaped leaf death (tip of leaf) and leaf vein browning (bottom right of leaf) are telltale symptoms of BOB.
BOB can have a severe impact on individual bur oaks (oak on the right), but not all bur oaks are affected by it (oak on the left).