WSU Extension

Hortsense

Plum, Prune (Fresh)
 
Disease
Armillaria root rot 
Bacterial canker 
Black knot 
Brown rot 
Crown gall 
Cytospora canker 
Plum pockets 
Russeting 
Shothole (Coryneum blight) 
Silver leaf 
Virus diseases 
Insect
Aphids 
Apple-and-thorn skeletonizer 
Brown marmorated stink bug 
Earwigs 
Fruittree leafroller 
Leafhoppers 
Pacific flatheaded borer 
Peach twig borer 
Peachtree borer 
Pear slug 
Scale insects 
Shothole borer 
Spider mites 
Spotted wing Drosophila (SWD) 



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Caption: Armillaria root rot infecting trunk
Photo by: C.R. Foss
  
Plum, Prune (Fresh) : Armillaria root rot
(revision date: 5/20/2014)


Biology
Armillaria root rot is a fungal disease often found in newly cleared soils or soils which have been flooded. Aboveground symptoms typically include production of smaller-than-normal leaves, leaf yellowing, premature leaf drop, and branch dieback, often on only a portion of the tree. The fungus may be found as white, felt-like masses beneath the bark at the crown, as honey-colored mushrooms at the base of infected trees in the fall, and/or as shoestring-like rhizomorphs, which are dark strands of the fungus growing on or just beneath the soil surface. Infected trees may also exhibit a dark black line in the infected area encircling the base of the plant. Trees damaged by human activity such as construction or improper irrigation are more susceptible.
Management Options


Non-Chemical Management
  • Use resistant rootstocks. Marianna 2624 rootstocks are reported to be resistant.
  • Provide proper culture. Healthy plants are more resistant to disease.
  • Remove damaged trees if necessary. When possible, remove roots 1" or more in diameter and air-dry soil before replanting.
  • Avoid injury to roots and trunk.
  • Replant with resistant species in infected areas. Lists are available in the PNW Plant Disease Management Handbook and the Sunset Western Garden Book, or contact your county Extension agent or WSU Master Gardeners.
Select non-chemical management options as your first choice!

Chemical Management

None recommended

Images

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Caption: Armillaria root rot infecting trunk
Photo by: C.R. Foss
Caption: Armillaria root rot infecting trunk
Photo by: R.S. Byther
Caption: Armillaria rhizomorphs
Photo by: R.S. Byther