Bacterial Canker Control

Plant Diseases & Solutions - Bacterial Canker Control & Treatment


Bacterial canker has been known to occur in stone fruits since the late 1800s. It can be a major component of the peach tree short life complex in southeastern United States peach orchards. This disease has sometimes been referred to as sour sap, blast, die-back, or gummosis. However, in the southeastern United States, gummosis is typically a reference to peach fungal gummosis
HOST PLANTS: Common in stone fruits such as cherries and plums but also observed in apricots and peaches.

SYMPTOMS: Bacterial canker is most severe in trees younger than seven years. Twig and branch die-back are often the first symptoms observed. However, twig die-back is preceded by the failure of flower and leaf buds to open in spring and subsequent development of elongated cankers at the base of one or more dead buds usually on the previous season’s terminal growth. Cutting into cankers reveals a brown margin, sometimes with streaks or flecks of necrotic areas extending beyond the surface canker margin. Trees diseased from bacterial canker may leaf out normally, but the foliage suddenly withers, turns brown, and dies. Closer examination usually reveals the presence of buds that failed to open with discolored bark and wood. Collapse and rapid tree death can occur within two months after bud break. However, in some instances trees will put out new shoot growth and recover if not affected by canker-causing fungi. After this period, it becomes very difficult to isolate the bacterial pathogen and to differentiate its symptoms from those caused by freeze injury, bacterial spot pathogen canker, and secondary microbes.

FAVORED ENVIRONMENT: Bacterial canker infections occur during fall, winter, and early spring (during cool, wet weather) and are spread by rain or water, and pruning tools. The bacteria overwinter in active cankers, in infected buds, and on the surface of infected and healthy trees and weeds.

BACTERIAL CANKER CONTROL: Prune flowering trees during blooming when wounds heal fastest. Remove wilted or dead limbs well below infected areas. Avoid pruning in early spring and fall when bacteria are most active. Make sure to disinfect your pruning equipment (one part bleach to 4 parts water) after each cut. If using string trimmers around the base of trees avoid damaging bark to prevent infection. Brush bark with white latex paint diluted with water to reduce bark-damaging temperature fluctuations. Trees may be protected with copper fungicides applied to the trunks and lower branches. Remove weeds and grass from around the base of young trees to improve air circulation and keep the trunk and crown dry. Spraying young trees with a copper fungicide prior to planting will help provide control.

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