It appears as wilting, sudden leaf death, browning at the margins, or browning between the veins. It is a product of the extreme temperatures and dry conditions that we've been experiencing. Seedlings and newly-transplanted stock are most susceptible due to their limited and shallow root system. Scorch has been noted on species of oak, ash and maple. Deep watering of the root systems in early morning and mulching around the base of the tree will help improve soil moisture.
Lesions are small, circular, rusty orange spots on the tops and bottoms of leaves.
These were infected earlier this spring by spores from the alternate host, juniper. Look for finger-like structures at the bottoms of the leaves as these will be releasing the spores which will infect juniper. Powdery mildew is becoming prevalent on broadleaf ornamentals at this time. It appears as a white to greyish powder on the tops of leaves. It thrives during hot days and cool nights so we can expect this disease to progress in August.