Hi Carissa,

Based on your photographs leaf scorch first comes to mind - physiological is more likely, although bacterial leaf scorch has moved into the Ohio Valley.  Given the weather we've had in late winter, and spring - extremes of cold and warm, heavy rains, and then long dry periods - many trees are showing signs of stress. Bacterial Leaf Scorch is not a disease that appears in the spring - it is seen in late summer, to early fall. I've included links below to help you look at the symptoms you see a little more closely to better differentiate between possible causes, and a brief description of Bacterial Leaf scorch.

Differentiating anthracnose and leaf scorch: https://bygl.osu.edu/node/364

Identifying causes of leaf scorch: https://bygl.osu.edu/node/1616

Leaf Drop Causes: https://bygl.osu.edu/node/2144

BACTERIAL LEAF SCORCH OF OAKS

During the Bluegrass BYGLive!, John Hartman took participants to view trees in Lexington, KY, that were suffering from bacterial leaf scorch. The causal agent is a xylem inhabiting bacterium, Xylella fastidiosa, that is thought to be transmitted from tree to tree by xylem-feeding insects such as leafhoppers (e.g. sharpshooter leafhoppers) and treehoppers (e.g. oak treehopper). However, since the disease spreads slowly from tree to tree, it is speculated that the insects are not very efficient vectors of the disease.

Bacterial leaf scorch has long been noted in the Atlantic and Gulf states and it has spread inland to the Ohio River valley. The disease has been detected in Kentucky for a number of years and has recently been found in southern Indiana. Ultimately, infected trees die from the disease and John indicated that some Lexington neighborhoods have lost over 70% of their mature red and pin oaks. While oaks remain the most dominant species affected in Kentucky, the disease has also been found on maples including red, silver, and sugar maple, as well as sycamore.

Symptoms vary somewhat between oak species. On pin oaks, scorching appears along the leaf margins and progresses inward toward the midvein. There is often a yellowish margin between the scorched leaf tissue and green tissue. On red oaks, the scorch typically appears at the leaf tip and progresses up the leaf towards the petiole. BYGLive! participants noted that the symptoms made the leaves look like they had been dipped in chocolate.

The timing of leaf scorch symptoms can present a diagnostic challenge. Infected trees often show no leaf scorch in the spring and early to mid-summer. Symptoms usually first appear as a few scorched leaves sometime in mid- to late August, but the scorching expands rapidly to involve other leaves in September and October. The challenge is that the symptoms can be easily mistaken for physiological leaf scorch or early fall color. However, since a number of other diseases, as well as cultural problems can mimic bacterial leaf scorch symptoms, John strongly recommended that suspected infections be confirmed by sending samples to a diagnostic clinic before concluding the tree is infected with the bacterium.

There is no cure for bacterial leaf scorch, so one should expect diseased trees to be gradually lost over the years. The best remedy for bacterial leaf scorch is tree replacement. However, in the meantime, infected trees can be made to look somewhat presentable for a few more years if the dead wood is pruned out. Since little is known regarding which species of insects serve as vectors for the disease, or exactly how disease transmission occurs, there are no insecticide recommendations available for disease prevention.

For a definite diagnosis of your issue you can provide a sample to the Ohio State University C. Wayne Ellett Plant and Pest Diagnostic Clinic, the instructions for submitting a sample may be found on their webpage:  https://ppdc.osu.edu/     Consulting a certified arborist is another option for getting a definite diagnosis.

Something else to consider when looking at the health of your trees is the quality of the soil, and how well the soil drains.  Soil tests for nutrients are available through the State, or your Union County Soil Conservation District. This fact sheet explains how, and why to test: https://ohioline.osu.edu/factsheet/hyg-1132   and here is the contact information for the Union County Soil and Water Conservation District:

Email <personal data hidden>  Phone Number <personal data hidden> ext. 4  Location18000 State Route 4Suite D Marysville, OH 43040

Kind Regards,