WSU Extension

Hortsense

Apple
 
Disease
Anthracnose and Bull's-eye rot 
Bitter pit 
Burrknot 
Crown and collar rot 
Crown gall 
Cytospora canker 
Fire blight 
Fruit russeting 
Nectria canker (European canker) 
Nectria twig blight (Coral spot) 
Perennial canker (Bull's-eye rot) 
Phytophthora fruit rot 
Powdery mildew 
Scab 
Virus diseases 
Insect
Aphids 
Apple ermine moth 
Apple maggot 
Apple-and-thorn skeletonizer 
Brown marmorated stink bug 
Codling moth 
Cutworms and armyworms 
Earwigs 
Fruittree leafroller 
Leafhoppers 
Leafrollers 
Lecanium scale 
San Jose scale 
Spider mites 
Tent caterpillars 
Tentiform leafminer 



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Caption: Apple crown and collar rot
Photo by: J.W. Pscheidt
  
Apple : Crown and collar rot
(revision date: 5/20/2014)


Biology
Crown rot of the rootstock and collar rot of the scion wood of apple trees is caused by a soilborne fungus. It can survive in infected tissues and plant debris, as well as in the soil. Symptoms typically appear in early fall, when one or more branches show signs of decline, including discolored (reddish-bronze to purple) foliage, smaller leaves and terminal growth, and a red discoloration of the bark. Infection occurs in the roots and moves within the roots to the crown. The bark is killed, and the cambium beneath the bark turns reddish-brown, instead of the normal white color. Crown or collar rots may completely girdle trees, resulting in death.
Management Options

Non-Chemical Management
  • Plant disease-resistant cultivars such as 'Antonovka', 'Delicious', and 'Wealthy'. 'Golden Delicious', 'McIntosh', and 'Rome Beauty' are moderately resistant.
  • The rootstocks M9 (highly resistant) and M2, M7, M26, and MM111 (moderately resistant) resist crown and collar rot.
  • Do not overwater or allow water to pool at base of trees.
  • Avoid wounding crowns and collars.
  • Cut out diseased tissues from crowns in dry weather and leave wounds exposed to the air.
Select non-chemical management options as your first choice!

Chemical Management

None recommended

Images

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Caption: Apple crown and collar rot
Photo by: J.W. Pscheidt