Answer: It's hard to tell from your description whether your plant has insect, disease, or environmental damage. Insects like leafminers can make tunnels on the inside of the leaf when they feed on tissue between the upper and the lower surfaces of a leaf. Some fungal diseases can cause spots on leaves that are 'zonate', or marked with concentric rings. Finally, water droplets on leaves exposed to sunlight can concentrate the sun's intensity and cause round spots with dark centers and lighter margins. Without knowing precisely what the problem is, it's difficult to suggest a remedy. If the plant isn't completely involved, you can remove the affected leaves. Otherwise, you might want to take the plant, or an example of the damage to your local extension service for a positive identification of the problem. Contact Penn State University Cooperative Extension, 217 Ag Administration Bldg., University Park, PA 16802. Phone (814) 865-2541.
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