Tree & Shrub Diseases


Fireblight

Description: Fireblight is a contagious disease affecting apples, pears, and some other members of the family Rosaceae.

The term “fireblight” describes the appearance of the disease, which can make affected areas appear blackened, shrunken and cracked, as though scorched by fire.  Primary infections are established in open blossoms and tender new shoots and leaves in the spring when blossoms are open.

 


Cedar-Apple Rust

Description: Cedar-apple rust is caused by a fungal pathogen called Gymnosporangium juniperi-virginianae.

This fungus attacks crabapples and apples (Malus sp.) and eastern red cedar (Juniper). In order to survive, the fungus must “move” from one type of host to another (e.g., from juniper to crabapple).

 


Oak Wilt

Description: Oak Wilt is a fungus caused the pathogen Ceratocystis fagacearum.

The fungus attacks most oaks and has also been found in Chinese chestnuts. The trees in the red oak group are very susceptible and tend to die in one year. Occasionally a few trees in the red oak group may live into their second year before they die. Oaks in the white oak group are more resistant and the disease is often localized and therefore may last for many years. Oak wilt is spread via root grafts, animals, tools and insects.

 


Chlorosis

Description: Iron chlorosis is a yellowing of plant leaves caused by iron deficiency that affects Some oaks (especially pin oak).

The primary symptom of iron deficiency is interveinal chlorosis, the development of a yellow leaf with a network of dark green veins.

 

 


Dutch Elm

Description: Dutch elm disease is caused by a fungus, which blocks the water-conducting tissue of the tree, and is spread by two species of bark beetles. These beetles feed, breed and over-winter on the wood of both live and recently killed elms.

Initial symptoms include discoloration and wilting of foliage on small branches high in the tree crown. The wilt symptoms spread until, eventually, foliage throughout the crown wilts and yellows, and the tree dies.