Photo credit: British Columbia Ministry of Agriculture and Land.įigure 2: Early shoot blight symptoms, note: 'Bacterial ooze'. Blossom Blightįigure 1: Blossom blight symptoms on pear. To obtain optimal control of the disease, an integrated pest management approach must be used, taking each of the factors described into consideration. This factsheet contains information on a variety of practices that you can use to help manage fire blight. Methods for Fire Blight Management in Your Orchard With all the different factors involved in fire blight management, integrated pest management strategies are essential. The use of Apogee® in mature bearing trees where blossom blight has been detected may help reduce susceptibility to the disease. The use of control products (copper or Bordeaux mixture before buds open, streptomycin for blossom blight control in combination with a prediction model to time bloom applications) will help limit disease spread. An annual pruning program to remove as many fire blight cankers as possible is critical. An integrated pest management program for sucking-piercing insects (for example leafhoppers, aphids, plant bugs) should be implemented. The application of excess nitrogen should be avoided. Sites chosen for orchards should have well drained soils with a pH between 5.5 and 6.5 and have adequate organic matter. Risks can be minimized by selecting cultivars and rootstocks carefully when planting new orchards (a list of the susceptibility of some common cultivars and rootstocks is included in this publication). Today, the trend is to plant higher density orchards with more valuable cultivars (many of which are highly susceptible to fire blight), making it difficult to avoid the disease all together. How do I avoid problems with fire blight in the future? Such a program should include diligent pruning to remove cankers in the winter, pruning during the growing season the removal of blight symptoms as they appear, a balanced nutrition program and the use of prediction models to determine appropriate timing for the application of control products to limit the spread of the disease. There is no cure for fire blight, but the spread of bacteria can be limited by using sound pest management strategies in an integrated management program. How do I save my trees once they are infected with fire blight? Blossom infections often result in shoot infections later in the season. Rainfall, high relative humidity and/or dew allow the bacteria to travel into the stigma of flowers and into the tree. Bacteria are spread to blossoms by insects (for example flies, honeybees) and splashing rain. In the spring, the bacteria can multiply very quickly, causing the surfaces of cankers to ooze bacteria. Where does fire blight come from?įire blight bacteria overwinter in cankers or strikes on host trees. Infections can also be identified by the discharge of bacterial ooze from infected plant surfaces. Cankers are typically smooth edged when first formed, but the margins become cracked and more pronounced with time. Cankers (Figures 5, 6 and 7) form once fire blight progresses into larger branches, trunk and the rootstock. Shoot blight (Figures 3 and 4) is characterized by the typical 'shepherd's crook' symptom. Blossom blight (Figures 1 and 2) results in blackened/shrivelled blossom clusters. The symptoms of fire blight depend on the part of the part of the tree that is attacked. Trees may need to be removed and replanted or, in severe cases, whole blocks of trees may need to be replaced. Economic losses to fire blight occur due to a loss of fruit-bearing surface and tree mortality. The severity of disease is dependant on cultivar and rootstock susceptibility, general tree health, cultural practices and environmental conditions. In severe cases, when the bacteria progresses into the trunk or infects the rootstock, entire trees can be killed. The disease can result in the loss of branches and tree structure. See Cedar-Apple Rust and Table of Juniper, Hawthorn, and Crab Apple Resistant to Rust Diseases for more information.Fire blight, caused by Erwinia amylovora, is a bacterial disease of apple, pear, hawthorn, crabapple and ornamentals in the Rosaceae family. These cultivars should receive first priority when control is required. Control always needed where disease is prevalent. Control usually needed where disease is prevalent. Control needed only under high disease pressure. (Very few cultivars in this category for any disease.) Apple cultivarĬedar-apple rust susceptibility rating (z) This table lists the susceptibility of various apple cultivars to cedar apple rust. The fungus can infect leaves and fruit of most cultivars in the eastern region. It is caused by Gymnosporangium juniperi-virginianae. Cedar-apple rust is a fungus disease of apple and cedar and spends parts of its life cycle on each host.
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