![]() ![]() Removal of cankers is a critical step in preventing and controlling fire blight. Cultural Controlįire blight overwinters in old dormant cankers in the trees. Double Nickel can be safely combined with Cueva (copper octanoate) for improved effectiveness. For best results, apply during early bloom at the beginning of a warming trend, and follow with Streptomycin or Kasumin 2 - 3 days later if warm temperatures continue to favour blossom infection.īiological fungicides are often sensitive to fungicides. These biopesticides should be used as part of an integrated fire blight management program, which includes using a risk assessment model, as well as cultural controls and antibiotic sprays when necessary. Most of these products consist of live, beneficial bacteria or yeasts which colonize blossoms and help to prevent fire blight bacteria from getting established. These products are blossom protectants, used during bloom to reduce the incidence of blossom blight. There are several biopesticides registered for suppression of fire blight on apple and pear (see table below). Wind damaged leaves are also susceptible to infection. Hail storms often result in severe fire blight outbreaks if inoculum is present in an orchard. Bacteria can enter the host through both wounds and natural openings such as lenticels. In these situations the disease pressure is usually low and the damage is more easily controlled. However, it is possible for twig or shoot infection to occur in orchards where little or no blossom infection was found. The worst epidemics always follow blossom infection. Secondary infections may continue to occur throughout the growing season. Infected shoots provide additional sources of fire blight bacteria, which can be spread by rain, (especially wind-blown rain), insects, and contaminated pruning tools. ![]() Blossom infections become visible as "strikes", or dying shoots in anywhere from 1 to 4 weeks, depending on the temperature. Once blossoms are infected, the bacteria can quickly spread into shoots and branches. This gives fire blight explosive potential if the conditions for blossom infection are met. Bacteria can then be spread very efficiently from blossom to blossom by honey bees. If weather conditions are warm and humid, the bacteria are able to multiply rapidly in the blossom nectar. This ooze, consisting of millions of bacterial cells, is spread to blossoms by insects such as flies, ants, and beetles. During spring and early summer, cankers that were not removed the previous season may produce bacterial ooze, which may or may not be visible. Note blackened leaves and fruitletsįire blight bacteria overwinter primarily in cankers on infected trees. Note browning of leaves andĭroplets of amber coloured bacterial ooze on fire blightįire blight-infected apple fruitlet, with bacterial ooze Later in the season the bark often cracks around the margins of the canker.īlossom blight on pear. Reddish brown streaks may be seen in the cambium under the bark of diseased branches. In susceptible hosts or young trees the disease may travel rapidly down branches causing girdling and death of the branches or sometimes the main trunk.Ĭankers appear as slightly darker, water soaked areas in the wood, which may produce amber coloured bacterial ooze that runs down the bark. When shoots attached to scaffold limbs or trunks are attacked, the pathogen may spread into the structural wood causing cankers. Blighted leaves may remain attached to the tree throughout the winter. During warm and humid or rainy weather drops of milky to amber coloured bacterial ooze frequently appear on the blighted shoots and fruit. Infected shoots (or "strikes") wilt rapidly, and often form a shepherd's crook at their tips. ![]() ![]() Fruitlets quickly turn brown to black and eventually shrivel up.īlighted pear shoots are black in colour, while infected apple shoots are usually a lighter shade of brown. Young fruitlets are also very susceptible and appear water soaked and slightly off-colour soon after infection. Blighted blossoms appear wilted, shriveled and brown or black. Symptomsįire blight symptoms may appear on the blossoms, shoots, branches, trunk and rootstock. Risk of fire blight is strongly related to weather conditions, history of fire blight in the area, and susceptibility of the host tree. Outbreaks of fire blight occur sporadically in British Columbia pear and apple orchards. It causes severe blighting of blossoms, shoots, limbs and fruit, and can kill young trees. Fire blight is a destructive bacterial disease of apple, pear and other related species such as crabapple, hawthorn, quince and mountain ash. ![]()
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