How to Treat Shot Hole Fungus in Plum Trees

Shot hole fungus, also called coryneum blight, is a fungal infection that causes numerous small holes in the plum tree's leaves. The infection first presents with tan spots on the leaves, which later fall out. The plum fruit develops discolored, sunken spots and twigs and branches develop lesions and cankers. Typically, the tree dies within five to 10 years if left untreated. If you notice signs of infection on one of your plum trees, it will likely spread to others nearby. Treat shot hole fungus on plum trees with the proper fungicide and by removing diseased portions of the tree.

Rake
Pruning shears
Hydrogen peroxide, rubbing alcohol or bleach
Chlorothalonil fungicide
Fertilizer

Instructions

- 1
  Rake up the fallen, diseased leaves and discard them in the trash. Do not leave them near the plum trees because this encourages the spread of the fungus.
- 2
  Remove diseased branches and twigs with a pair of pruning shears. Disinfect the pruning shears after use with hydrogen peroxide, rubbing alcohol or bleach to prevent the shot hole fungus from spreading to other plum trees. The disease overwinters in affected twigs and branches, which ooze the bacterium from any lesions, spreading the disease to other parts of the tree, according to the Nebraska Department of Agriculture.
- 3
  Apply a chlorothalonil fungicide to the infected plum tree when the petals begin to fall in the late spring or early summer. Do not wait so long to apply it that the flowers that cover the immature plums begin to fall off. Control shot hole fungus on a long-term basis by applying chlorothalonil once every year.
- 4
  Apply a fertilizer in the early spring to reinvigorate your plum trees and help it recover from pruning. Use a well-balanced fertilizer like 10-10-10. Give each plum tree 8 ounces of the fertilizer per year of growth. For example, if your plum tree is 2 years old, give it 16 ounces.

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