Southern Blight in Apple Trees

Southern blight is a fungus disease caused by Sclerotium rolfsii. The disease is a problem primarily in the Piedmont apple growing region in the southeastern United States. S. rolfsii is a widespread pathogen that affects several hundred plant species. The fungus affects the lower stems and roots of apple trees, killing the bark and girdling the trees. The disease is characterized by the presence of a white, weblike mycelium, which often forms at the bases and on the lower stems …

White Root Rot of Apple

White root rot, caused by the fungus Scytinostroma galactinum (formerly Corticium galactinum), has been known as a parasite of apple trees for many years and is widely distributed (Canada to Texas and westward to the Pacific coast, Europe, West Indies, and Japan). It occurs in both bearing and non-bearing apple orchards. Other hosts include a wide variety of woody plants, ornamental shrubs, and herbaceous perennials, including white pine, ash, peach, blackberry, dewberry, Japanese wineberry, dogwood, sumac, white campion, holly, …

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 …

Armillaria Root Rot of Apple

Armillaria root rot, also known as shoestring root rot, is a soilborne disease that can affect several fruit crops. However, it is most common in the eastern United States on peach and apple trees. Its host range also includes numerous species of deciduous and evergreen trees, shrubs, and woody vines. The greatest prevalence of the disease is in orchards planted on newly cleared land in which the soils are sandy and well-drained. In these locations, pieces of wood invaded by …

How do I identify and manage Armillaria root rot, or shoestring rot, in apple?

Armillaria root rot, also known as shoestring root rot, is a soilborne disease that can affect several fruit crops, but it is most common in the eastern United States on peach and apple trees. Its host range also includes numerous species of deciduous and evergreen trees, shrubs, and woody vines. The greatest prevalence of the disease is in orchards planted on newly cleared land in which the soils are sandy and well drained. In these locations, pieces of wood invaded …

Black Root Rot of Apple

Black root rot, also called dead man’s fingers or Xylaria root rot, is occasionally observed on mature apple and cherry trees. Although trees of all ages can be infected, most trees that die from black root rot are at least 10 years old. Black root rot is caused by two species of the fungus Xylaria: X. mail and X. polymorpha, with the former more common in southern Appalachian states and the latter more common in eastern states. The disease …