What diseases are problematic when planting apple trees in heavy soils?

Heavy soils are those that contain more clay particles relative to sand and silt components. The high clay content causes the soils to be less friable, making them “sticky,” and more dense, thus making them hard to work with. They often remain cold and wet in spring and need grit or coarse organic material to admit air and help roots remain healthy. Because of their tendency to be cold and wet for longer periods than lighter soils, there is an …