This is my second season growing morning glories. They look like they are doing great, then all of a sudden the leaves start getting yellow specks, then spreading to the whole leaf. It starts mostly at the base of the plant. Also, every afternoon the plant starts wilting. I read that they don't like a lot of water, but they wilt up everyday.
Morning Glory plants will show sun wilt in the warm summer days. They will recover each night.
The yellow specks could be insects or fungus issues. Treat with Neem Oil as it works as both an insecticide and fungicide. It is also safe for people, pets and bees.