![]() ![]() One of the earliest symptoms of the disease occurs on flowers and is "blossom blight." The blossoms appear discolored (water soaked, gray-green color progressing to black). Secondary infections on young shoots are common following injury caused by hail, wind-blown dust, or insects. Infected tissue turns brown to black, shrivels and droops, but remains attached to the tree. The infection moves from blossoms to young fruit and then to adjacent leaves. The bacterium enters the plant through blossoms, wounds, and natural openings (such as stomata, hydathodes, lenticels, and nectaries). In spring when the bacterium becomes active, wind-blown rain or insects spread it from oozing cankers to blossoms. During periods of high humidity, infected tissue may produce a characteristic ooze. Fire blight can infect blossoms, fruit, stems, leaves, and woody branches. The characteristic symptom of fire blight is that affected plant parts (most notably the branch terminals) appear to have been scorched by fire (fig 1). Other hosts include rose, quince, hawthorn, loquat, almond, apricot, plum, cherry, chokecherry, mountain ash, raspberry, blackberry, and strawberry. In New Mexico, the disease is most common on apple, pear, crabapple, pyracantha, photinia, and cotoneaster. Within this plant family, the bacterium infects at least 39 different genera. It affects only plants in the rose family (Rosaceae). In commercial orchards, spray with bactericide.įire blight, caused by the bacterium Erwinia amylovora, is one of the oldest known bacterial diseases of plants.Sign: Watery ooze produced from infected plant tissue. Key symptom: Branch tips turn black as if scorched by fire. Hosts: Plants in the rosaceae family, notably apple, pear, pyracantha, cotoneaster, and photinia. This publication is scheduled to be updated and reissued 2/04.Ĭausal agent: Erwinia amylovora, a bacterium. Goldberg, Extension Plant PathologistĬollege of Agricultural, Consumer and Environmental Sciences New Mexico State University. Unfortunately, there is no 100% effective prevention measure for Fire Blight, and the best way to avoid damage is to carefully monitor your trees for early signs and prune out as soon as possible.Natalie P. ![]() A copper sulfate spray in early spring can also reduce the rate of infection. Prevention of Fire Blight starts with selecting disease resistant varieties of your trees (see below). This can be done by dunking or wiping your pruner or saw blade or by using a spray bottle to coat the blade in between each cut. Use rubbing alcohol (70% concentration preferred) or a 10% bleach 90% water solution to sterilize. It is very important to sterilize your tools between each pruning cut (a good general practice anytime you’re pruning during the active growing season) to avoid spreading the disease. Pruning cuts should be made into healthy wood, at least 6 to 12 inches below where you see any sign of infection.Ĭheck out POP’s YouTube Channel for other videos on ecological orchard care! Prune off diseased wood as soon as you notice it to prevent it from spreading. During the summer, the best way to prevent additional fire blight spread is to control sucking insects like aphids and leafhoppers.Īn otherwise healthy tree showing signs of Fire Blight can be cared for and managed through pruning of damaged areas.When growth stops, the spread of fire blight should also stop. It is not recommended to cut out infected shoots after terminal growth has stopped.If burning is impossible, you can dry out branches thoroughly and mulch them later with a chipper. For disposal of infected branches, prunings should ideally be burned offsite from the orchard.When pruning larger limbs, consider using the ugly stub method: make a cut about 6-12 inches below the fireblight and if the location of the cut is awkward, then remove the remainder of the branch later during winter pruning.Always prune into healthy wood, 6 to 12 inches below the visible signs of fireblight.It is most effective to prune trees where there is a low incidence of fire blight.Try to cut out infection before the signs of necrosis (singed/ burned appearance in leaves).Infection spreads through moisture and rainwater. If possible, wait until the weather is dry before pruning.If you notice signs of infection, keep these things in mind: In the growing region in and around Philadelphia, you may begin to observe signs of infection in late spring, around May 25th. It is important to take action early in order to most effectively prevent the spread of Fire Blight. Fire Blight can also infect fruit, which appear blackened and shriveled. ![]()
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