The organisms cause yellow spots on the leaf surface between the veins. These spots keep spreading until the veins turn brown. When the whole leaf goes brown, it falls off. If the plant loses too many leaves, it dies.
The undersides of the leaves may have a fuzz that varies from white to purple in terms of color. Consequently, the fruit growth may stop because the leaves no longer shade them. Then the fruits rot or get sunscald.
You may also notice white blister-like growths on the lower side of the leaves. The stems may be covered in it too. If you dig up the soil around the roots, you may find them swollen. Other symptoms include flower deformation and chlorosis (leaf yellowing).