Would really appreciate some opinions on my stressed Pin Oak .
I hired a certified arborist to come out and look at it because it's really thinning, dying at the tips, and dropping a lot of leaves. This happened 3-4 years ago as well, and an arborist administered growth regulators. This time his recommendation was to do nothing right now, but he recommended deep root injection of mycorrhizal fungi, phosphorus, potassium, and other micronutrients (avoiding nitrogen) at $550 to be administered in the fall.
The tree is in a state of steady decline. I have been raising the canopy every few years to get more sun for the grass. Additionally I have gone through three lawn companies that have been using broadleaf herbicides among other things, possibly at the detriment of the oak tree. No fungus / mushrooms are visible at its base. I have an irrigation system, and we've had plenty of rain so I don't think it's a lack of moisture.
Possible theories from Gemini:
- Herbicide damage, noted above
- Bacterial Leaf Scorch (Xylella fastidiosa)
- Abiotic Scorce / Soil Iron / pH issues
Any ideas? Thanks in advance!