Although bacterial canker is more serious on sweet cherry trees, it also affects peaches, prunes, plums, apricots, and almonds. The same bacterium also can cause a blight of many other fruit, vegetable, and ornamental crops.

‘Royal Ann’, ‘Bing’, ‘Lambert’, and ‘Van’ are very susceptible to bacterial canker. ‘Corum’, ‘Sam’, and ‘Sue’ appear to have sufficient tolerance to canker to be grown commercially without serious tree loss. Mazzard seedlings, particularly the F12-1, seem the most resistant rootstocks. Size controlling rootstocks may also have useful resistance but field performance trials are lacking. Trees on Gisela rootstock have exhibited increased susceptibility.

Cankers caused by the bacteria may be on the trunk, limbs, and twigs. Typical cankers are much longer than broad, but a canker may girdle the infected limb or trunk. The cambium at the canker will be discolored and necrotic. Use a pocket knife to reveal this discolored tissue. Cankers develop in winter and early spring. As the tree begins growth in spring, the bacteria population declines and a callus layer forms around the canker’s edge. During spring and summer, girdled and nearly girdled limbs may leaf out. Normally, leaves turn yellow, then the limbs usually die. In some instances, these symptoms may not appear until late summer when the leaves’ water requirement is high.

Dead bud "disease" is first noted as dying buds on spurs in spring. Infected buds usually start to die in February. As the disease progresses, both leaf and flower become infected. Dead bud usually starts in lower limbs and moves up the tree and to adjacent trees in successive years. Often, trees in the lower orchard, where air drainage is poor, are the first to be infected. If all buds on a spur are killed, the spur will die back next season. Cankers very seldom form, but the diseased buds may produce a slight gumming. Repeated death of buds may result in misshaped growth and sometimes fasciation. In severe cases, 90% or more of buds on a tree may be killed.

The cultivars 'Royal Ann', 'Bing', 'Lambert', and 'Van' are quite susceptible to dead bud. 'Black Republican' and 'Mazzard' seedlings are somewhat less susceptible.

Leaf and fruit spots are not common and are not numerous if they develop. Spots on leaves are at first water soaked, then become dry and brown.

1. The most effective control known is to use the resistant F12-1 Mazzard rootstock. Use only scions from virus-tested (and found to be free of all known viruses), canker-free trees. Make buds or grafts at least 12 to 15 inches away from the trunk. If F12-1 rootstock is unavailable, Mazzard seedling rootstock is the next best choice.
2. Do not interplant new trees with old trees which are a major source of the bacteria.
3. Locate orchard in an area less likely to be affected by frost. If planting in the spring, plant orchards after frost is likely to occur. Prevent winter injury by painting trunks white and avoiding late season fertility.
4. Test soil for ring nematodes before planting. Also test for incorrect pH and other physical characteristics that can be corrected prior to planting.
5. Provide optimal soil conditions for growing cherries including attention to pH and nutrition. Keep irrigation off above ground parts for the first few years.
6. Control weeds.
7. Delay dormant pruning until January or February. Summer pruning should be done after harvest, when weather is dry.
8. Completely remove infected trees or branches girdled and killed by cankers. Do not allow trees to regrow from roots or trunks left after a major trunk canker has been removed.
9. In summer, small cankers may be cut out using the following method. Cut away bark above and around the edges of the infected area. Use sharp tools, and leave wound margins smooth and neat. In nonirrigated orchards, wounds may be left uncovered during summer but should be treated with a wound dressing before fall rains begin. In sprinkler-irrigated orchards wounds may be soaked frequently, so they should be covered with a dressing as soon as possible after cutting. Sterilize all pruning tools between cuts with 10% Clorox (bleach) solution or shellac thinner (70% ethyl alcohol).
10. Cauterizing cankers using a hand-held propane burner has been used with some success in New Zealand.
11. Scoring tree trunks has been practiced by Willamette Valley growers for several years. Grower testimonials point to some benefits but there has been no research on this possible efficacy of the practice. A sharp pocket knife is used to make a vertical shallow cut in the tree trunk. The resulting wound tissue that develops is supposed to resist canker development and prevent trunk girdling. Knives should be disinfected between trees.

1. Bordeaux 12-12-100.
2. Champ Formula 2 at 1 gal/A. Champion WP can be used for organic production. 24-hr reentry.
3. C-O-C-S WDG at 8 to 12 lb/A plus dormant spray oil. 24-hr reentry.
4. Copper-Count-N at 6 quarts/100 gal water. Use only 2 to 3 quarts/100 gal water during bloom. 12-hr reentry.
5. Cuprofix Ultra 40 Disperss at 5 to 8 lb/A. 12-hr reentry.
6. Kocide 3000 at 3.5 to 7 lb/A plus 1 pint superior-type oil/100 gal water. 24-hr reentry.
7. Nordox 75 at 5 to 13 lb/A. 12-hr reentry.
8. Nu-Cop 50 DF at 8 to 12 lb/A. Nu-Cop WP can be used for organic production. 24-hr reentry.