Canker

• Canker is a dead area in a branch or trunk, infected with one of many fungi that enter through open wounds in the bark. The fungus then develops spores in the dead spots and these spores spread by wind or rain, entering and infecting surrounding branches that have wounded, damaged or cut areas.
  
  

What it Looks Like

• Oval-shaped, the cankers grow on branches and enlarge each year, swelling or sinking into the wood, causing decay. The fungal area is white to tan colored, and in high moisture conditions the color is a tan to orange shade. Darker, crusty areas may also appear from the disease. Each year the cankers grow larger and surround the stem, destroying it over time.
  
  

Types of Canker

• Both annual and perennial cankers develop on stressed chokecherries. Annual cankers exist for just one season and any infected areas heal over before the next growing season begins, causing no permanent damage to the shrub. Perennial cankers are visibly obvious and destructive to the plant, causing more damage each growing season by further girdling the branches, and if not addressed, eventually killing the plant. Some cankers produce spores for just one year, while others will produce for many years.
  
  

Controls

• Reducing the areas where the fungi can enter is essential in eliminating the occurrence or severity of stem canker. Do not plant new chokecherry next to infected shrubs and prune in the spring so wounds can heal along with the new season's growth. Remove cankered branches to prevent the spread and burn the cankered wood to destroy the disease. Drought, lack of nutrition, lawn mower damage and insect problems can also contribute to stem canker; work to avoid any additional stress on the shrub.