After our last treatment for spider mites in 2011, I thought we were seeing some improvement in the health of our Oak trees. With a very dry winter things have not gotten better and in some cases have become worse. We had another sample taken and along with the mites, the disease Coryneum was present.
Siting the report, "The fungus Coryneum is known to cause a twig canker of oak. Trees that are stressed by prolonged drought or other factors such as grade change, overly saturated conditions, soil compaction, sunscald, etc., are more prone to infection by this opportunistic pathogen." Without the aforementioned stressors, Coryneum isn't typically a problem. We are obviously experiencing drought, but what is often overlooked with median trees is compaction. Parking lots have to meet certain compaction criteria before asphalt can be applied.
Arborwell was back on site Tuesday and treated the trees with an insecticide for the mites, a fungicide for the disease, and a bio-stimulant to help aid in recovery. We have also been watering the trees with a root injection nozzle. It will be some time before we see any signs of recovery, but we can be assured that we have taken all the appropriate steps to cure the problem.