Why are the leaves on my dogwood tree turning yellow?
If your dogwood’s leaves are yellowing faster than the trees around it, or during a time of year that they normally wouldn’t, the likely culprit is a condition known as Chlorosis.
What Causes Chlorosis?
Caused by an iron deficiency, chlorosis is the result of your trees inability to absorb enough iron from the soil, making it difficult for it to produce chlorophyll. Chlorophyll is the chemical that gives the leaf its green appearance.
There are several reasons chlorosis may occur. If the soil in which your tree is planted in is too alkaline (having a PH above 7.5) then it will be unable to absorb enough iron.