Gummosis is a common name given to a bacterial infection in weeping cherry, and other stone fruit and ornamental trees, known scientifically as Pseudomonas syringae van Hall. According to H. Ronald Cameron at Oregon State University Corvallis, while gummosis can go by many common disease names including blast, die-back, soursap, blight, cherry gunuiosis and bacteriosis, bacterial canker is the preferred name used in the United States and Europe.
Gummosis commonly presents in weeping cherry as quick onset wilting, bud and bloom tissue death with extensive infections creating gummy weeping cankers in the wood, thereby killing it.
Spray your weeping cherry tree with a Bordeaux mixture bactericide product in the late fall or winter when buds are developing. Spray with an antibiotic streptomycin product in the spring and summer. Apply according to product label directions to control the spread and symptoms of gummosis.
Water deeply and consistently to spur new tissue growth and help the cherry outgrow the disease. Prevent any diseased tree from experiencing any drought conditions as this will exacerbate the stress on the tree, impair the flow of nutrients into and through the tree and can cause wilt to become permanent and the tissues to die back.
Fertilize your weeping cherry tree once or twice per year to keep nutrients flowing into the tree to support new tissue growth. Feed with a low nitrogen complete product with a guaranteed analysis of 5-10-10 according to the product label dosing directions and water in deeply until the soil is drenched at least 6 inches down.
Cut out diseased wood in the late spring and summer pulling it clear from the canopy and up from the soil below and burning or otherwise discarding the diseased wood far away from the tree. Sterilize your cutting tool blades between each cut and place all cuts back to the point of healthy tissue. Refrain from pruning or cutting the tree in wet weather.