Bacterial Spot on Stonefruit Trees

Encyclopedia Article

Overview of bacterial spot on stonefruit trees

Bacterial spot on fruit trees is caused by several bacterial pathogens. 

Signs and symptoms of bacterial spot on stonefruit trees

Leaves develop small, angular, water-soaked spots at the tip and the end of the leaf eventually turn brown or black. Centers of spots often fall out and are surrounded by a reddish margin. Severely infected leaves turn yellow and fall off.

Fruits become pitted or cracked if infected early in the season. Late-season infections are shallower, giving the fruit a mottled appearance.

Ecology of bacterial spot on stonefruit trees

The bacterium that causes bacterial spot survives the winter in cankers on shoots. In spring, bacteria ooze out of the cankers and are spread by windblown rain to leaves, fruit, and shoots.

Type of Sample Needed for Diagnosis and Confirmation of bacterial spot on stonefruit trees

The Iowa State University Plant & Insect Diagnostic Clinic can help you to investigate and confirm if you plant has this disease. Please see our website for current forms, fees, and instructions on collecting and packing samples. Contact information for each states diagnostic laboratory for U.S. residents.  If your sample is from outside of Iowa please do not submit it to the Plant & Insect Diagnostic Clinic without contacting us 

Image of shot hole symptoms caused by a bacterial pathogen in apricot leaves
Shot hole symptoms caused by a bacterial pathogen in apricot leaves

Management of bacterial spot on stonefruit trees

Several peach varieties with fairly good resistance are available. Consult the local extension office or garden center, and check nursery catalogs for resistant varieties. This is the best control option for peaches. Most apricot and nectarine varieties are susceptible.

If possible, locate new plantings away from older ones containing susceptible varieties.

Use a balanced fertilization program. Over-or under-fertilized trees are more vulnerable to bacterial spot.