WSU Extension

Hortsense

Kinnikinnick
 
Disease
Leaf gall 
Leaf spot 
Rust 
Insect
Aphid (Manzanita leafgall aphid) 



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Caption: Leaf gall
Photo by: R.S. Byther
  
Kinnikinnick : Leaf gall
(revision date: 1/22/2016)


Biology
Leaf gall of kinnikinnick is caused by the same fungus which causes leaf and flower gall of azalea. Initially, infected plant parts show a thickening and then gradually become fleshy in appearance. Infected leaves and flowers thicken into greenish to pinkish galls. As the galls mature, they become covered with a dense white coating of fungal spores. Galls finally become brown and woody. Healthy plants can easily tolerate considerable amounts of galling without serious damage.
Management Options


Non-Chemical Management
  • Pick and destroy thickened, fleshy leaves and flowers before the white fungal spores are present.
  • Remove all old galls from plants prior to bloom and flushes of new growth.
  • Space plants and prune to reduce humidity.
  • Avoid overhead watering or limit it to times when the foliage can dry quickly.
  • The variety 'Massachusetts' is reported to be resistant to leaf gall.
Select non-chemical management options as your first choice!

Chemical Management

Make two applications, the first before budbreak in spring and the second 2 to 3 weeks later.

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.
  • Bonide Copper Fungicide Spray or Dust RTU [Organic]
    Active ingredient: basic copper sulfate  |  EPA reg no: 4-58
  • This list may not include all products registered for this use.
Images

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Caption: Leaf gall
Photo by: R.S. Byther