Leaf scorch can affect pin oaks, sycamores

By ALAN WINDHAM / UT Extension Office

The affects of BLS are seen on this tree, located in front of NHC here in McMinnville. (Photo provided)

Bacterial leaf scorch (BLS) caused by Xylella fastidiosa is pretty common on pin oak and sycamore throughout the state. Pin oaks are scorching pretty severely in the Middle Tennessee area; symptoms are visible on sycamores also. Symptoms start as a marginal scorch of the majority of the leaves. Scorch of the whole leaf may follow as well as severe leaf drop.

Trees infected with BLS will decline over a period of years and die. As the disease progresses, the canopy of the tree will shrink each year. There are no cures for this disease. In most cases the disease is allowed to run its course. Remove the trees when they become too unsightly with many dead branches.

On another note, it’s a good ideal to look for obscure scale on pin oak branches when examining a tree in decline. Scale is another potential problem. It alone can kill a tree, limb by limb over time, but without the leaf scorch appearance. Obscure scale appears as flat, 1/8 inch round flecks that will scrape off a branch with the back of a knife. Check pencil to finger size branches. Take several branches to your local UT Extension office and ask them if they see any scale.