Q.Hydrangeas With The Brown Spots. You Said A Fungus. I Have Sprayed With A Fungicide.
It has not worked. It is now spreading to my other hydrangeas. The one I bought that was recommended is Monterey liquid copper fungicide. What more is there to do? I have cut off the leaves and burned them. The new leaves come back and the get this very quickly. I am at a loss.
I would recommend taking some leaf samples to your agriculture extension service. Fungicides do not necessarily cure but rather help to control infections. They should be used as part of an overall disease management program that includes clean sanitation practices. Without these practices, the spores can find a favorable environment and still germinate. Ensure that the leaves are never watered (rainfall is ok) and that there is good air flow). Discard the leaves directly in the trash instead of burning in case the spores are being spread by the winds. Do not let the various shrubs' leaves touch each other. The best results from fungicides occur when they are started as soon as there is leaf out or new stem growth. It may be necessary to switch to another fungicide active ingredient as the fungi becomes resistant to one active ingredient or better to rotate applications between two different active ingredients. Ensure you repeat the applications as often as directed for at least 1-2 years (do not stop; do not expect the injured lesions to turn green again). But first consider seeing what your agriculture extension service says. When doing that, mention the exact/full commercial name of the product you are using and its active ingredient. Monterey has several, different active ingredients in its Liquid Copper line of products (I personally know of them using at the least copper octanoate and copper diammonia diacetate but there may be others).
