WSU Extension

Hortsense

Ornamental Plum
 
Disease
Armillaria root rot 
Brown rot 
Crown gall 
Cytospora canker 
Plum pockets 
Shothole (Coryneum blight) 
Silver leaf 
Viruses 
Insect
Hop aphid 
Leaf curl plum aphid 
Peachtree borer 
Pear slug 
Scales 



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Caption: Armillaria root rot infecting trunk
Photo by: C.R. Foss
  
Ornamental Plum : Armillaria root rot
(revision date: 4/28/2014)


Biology
Armillaria root rot is a fungal disease transmitted between plants by root contact. Armillaria is often found in newly cleared soils or ones which have been flooded. Symptoms typically include sudden or gradual slowing of growth, yellowish or undersized leaves, leaf drop, dieback of branches, or gumming (sticky, oozing sap). White thread-like masses of the fungus may be found beneath the bark near the crown of infected trees, and/or as shoestring-like rhizomorphs, which are dark strands of the fungus growing on or just beneath the soil surface. Honey-colored mushrooms often grow near the base of infected trees in the fall. Infected trees may also exhibit a dark black line in the infected area encircling the base of the plant. Armillaria-infected trees have damaged root systems and are more likely to fall in high winds. It may also make trees more susceptible to insect attack
Management Options


Non-Chemical Management
  • Remove infected plants, including roots larger than 1" in diameter.
  • Air-dry soil from infected site before replanting.
  • Provide proper culture to decrease stress and encourage vigorous, disease-resistant trees.
  • Plant only resistant plant species in infected areas (when possible). A list may be found in Revised EB 1776, the Sunset Western Garden Book, or by contacting 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
Caption: Cherry Armillaria root rot
Photo by: R.S. Byther