If any tubers are seen above the mulch, be sure to apply more mulch. Exposed potatoes can cause the sun to turn the skin green. This green skin is poisonous and should not be eaten. Sometimes potatoes will bloom and produce a small green tomato-looking fruit. This fruit is also poisonous.
Potatoes require moderate amounts of nitrogen.
A good organic source is composted manure. Phosphorous and potassium requirements are on the high side. This will encourage proper root development. Cotton seed meal, bone meal, and potash are some beneficial ingredients for an organic fertilizer. Black leg , Early blight ,Internal black spot, Mosaic , Rhizoctonia, Ring rot , Scurf , Soil rot , and Verticillium wilt .