Constriction canker is found most frequently in older, established orchards and appear to be more common on certain varieties of peach trees. Reddish brown zonate or concentric lesions appear on the bark around the branch nodes of last year's shoot, usually by late autumn. Over time, these cankers become sunken and turn tan to silver in color. Often, these zonate bands are speckled with tiny dark brown dots, corresponding to fungal structures embedded in the bark. These specks are not found in brown rot, a disease that also causes shoot canker. The necrosis may encircle the branches and lead to shoot dieback in very susceptible varieties, often associated with warm temperatures. Fruit loss is to be expected, since these are the fruit-bearing branches for the current growing season. Gumming may occur at the base of infected shoots.
Constriction canker is a fungal disease caused by the fungus Phomopsis amygdali. It produces spores on structures that are sometimes visible as dark brown specks within the cankers. These spores are later released and spread by rain splashes and winds to other branches or trees, where they initiate new infections. Leaf wounds are the main entry point for the pathogen all year round, although scars on buds, fruits and blossoms can also play a role in the progression of the infection during the spring. The fungus then grow in the internal tissues, producing new cankers and eventually killing the shoots. Moist warm weather offers the best settings for the growth and dispersal of fungal spores.
Constriction canker is found most frequently at high levels in older, established orchards. Constriction canker appears to be more common on certain varieties.Sorry, we don't know of any alternative treatment against Phomopsis amygdali . Please get in touch with us in case you know of something that might help to fight this disease. We are looking forward to hearing from you.
Always consider an integrated approach with preventive measures together with biological treatments. To have a better outcome it is important to combine fungicide treatment with mechanical canker removal. Fungicides containing chlorothalonil, captan, thiram or ferbam can be used as spray applications on affected branches. DMI fungicides, benzimidazoles and strobilurins can also be used, but are less effective. In moderately to severely infected orchards, fungicide applications are recommended at 10-14 days intervals, starting at the beginning of autumn and ending after leaf fall. The maximum number of applications during that period should not exceed six to seven. Note that none of the stated fungicides are able to control the disease completely.