My Chestnut Oak tree has Phytophthora Canker disease. Can I treat it myself?...
There is no control for canker disease. Phytophthora fungal disease is soil-borne and typically enters a tree's vascular system through a wound in the roots or trunk at soil level. The phytophthora spores thrive in very moist soil and the disease is usually contracted by plants that are situated in poorly drained areas.
In spite of that, the only tactic available to homeowners is to keep the tree as healthy as possible, and that means providing supplemental irrigation during droughty periods. Dead limbs should be pruned out and destroyed. Trees with only minor cases of P. canker are sometimes able to recover.
You didn't indicate as to who made the diagnosis, but if you have any doubts, you are invited to send us a photograph of the symptoms you consider most significant and our pathologist will confirm.
It was diagnosed by Bartlett Tree Experts. They were to apply Bartlett Boost Chesapeake 25-0-12 to help correct nutrient deficiencies ($177) and perform a bark treatment to suppress the Canker disease ($223). Trying to avoid the costs if possible.
Certainly you can fertilize the tree yourself. http://extension.umd.edu/learn/fertilizing-landscape-trees-and-shrubs-hg23 We do not know what they are planning to use to "suppress the canker disease". Phytophthora is not something that a homeowner can cure. Lots of chestnut oaks are in decline and saying for sure what is causing the decline is extremely difficult and saying what will diminish or halt the decline is even more difficult. Keep the tree watered deeply in time of drought. If the surrounding soil is compacted, aerate it. You might ask Bartlett if they think the treatment that they will use will cure the tree or if it will help the tree and if so to what degree. Then you can decide if you want to invest in your tree or if you want to get another estimate. vw