All are caused by all the same organism, Botryosphaeria obtuse, but the common names refer to the different stages of the disease. This disease can attack many kinds of trees and shrubs, not just apple trees, especially when wood is weak or dying. For example in grapes, it is known as dead arm. The Frog eye leaf spots appear to have rings of brown with a purple margin, thus giving it its frogeye appearance. The apple flesh that has decayed is firm and slightly leathery in appearance.
Applications of fungicides must be done in conjunction with sanitation. Good sanitation reduces inoculum levels in the orchard. Carefully prune out dead wood, cankers and other infected wood such as from fire blight in apples. Properly dispose of prunings and all mummified fruit by burial or burning.