How to Treat Orange Tree Leaf Fungus
My grandfathers orange trees have black bumps on the bottom of the leaves. They look like flea eggs in size and texture. This is the first year he has had this problem. The trees have been there for over 15 years. He grew up in Florida and remember using an oil to treat the trees. He thinks it was whale oil. He live in Houston,TX. They do wipe off with a rag. Any idea about what this is and the best thing to use would be helpful.