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amylovora is found in most areas of the province where apples are grown. Raspberry can be infected by fire blight bacteria, but the raspberry strain cannot infect apple, pear or ornamental plants. The host plants include quince, crab apple, hawthorn, cotoneaster, mountain ash and firethorn. The disease is caused by a bacterium, Erwinia amylovora (Burrill), which infects hosts in the Rosaeceae family. Through his programming, he aims to increase backyard food production and foster a greater appreciation of insects.Fire blight is a serious disease causing considerable damage and economic losses in apple and pear. Ken provides horticulture programming with an emphasis on fruit and vegetable production, pest management, and beneficial insects. Ken Johnson is a Horticulture Educator with University of Illinois Extension, serving Calhoun, Cass, Greene, Morgan, and Scott counties since 2013. Signup for our emails! Want to get notified when new Good Growing posts are available? SIGN ME UP According to the University of Kentucky, at 70☏, the bacteria can double every 20 minutes, meaning one cell can become one billion cells overnight. Good Growing Tip of the Week: Under ideal conditions, the bacteria that causes fire blight can rapidly increase. They can't cure the disease, only prevent it

Do not use after fire blight symptoms have developed.

Do not apply more than three or four times in a season (when plants are blooming).

Only use the rate recommended on the label.

If you use an antibiotic spray, take steps to reduce the chances of resistance developing: If Stryptomyacin is not used properly, there is a risk that the fire blight bacteria can develop resistance to it. Streptomycin will kill the fire blight bacteria, preventing it from infecting the flowers. Streptomycin (an antibiotic) can be used during bloom to protect flowers. This can help reduce the amount of bacteria that builds up on the surface of the trees. As with all pesticides, make sure to follow all label directions.Ĭopper compounds can be sprayed during the dormant season and at green tip. However, there are some pesticides that can also be used to help manage fire blight. These can lead to flushes of new growth, which is highly susceptible to fire blight.īecause the pathogen that causes fire blight is a bacteria, fungicides won't work to control it. Regardless of when you prune your trees, make sure to destroy (burn, bury, etc.) or remove the infected plant material from your landscape.Īvoid overfertilizing trees and excessively pruning apple and pear trees during the growing season. If you have a Callery pear that is infected with fire blight, make a pruning cut at ground level and replace it with a more desirable species. Prune 6 to 12 inches below visible symptoms, and make sure to sanitize pruners between each cut. If you feel you need to prune during the growing season, make sure to do it when conditions are dry to reduce the chance of spread. Infected branches should be pruned at least 6 to 8 inches below cankers and infected areas. This is best done while the plants are dormant to avoid spreading the bacteria to healthy parts of the plant (or other plants). Infected stems and branches should be pruned out of the tree. While they are not completely immune to fire blight, resistant varieties are less impacted by the disease than other varieties.

Pear varieties that have some resistance include Magness, Maxine, Moonglow, and Summercrisp. Apple cultivars such as Gold Rush, Empire, Enterprise, Liberty, and Winecrisp have some resistance to fire blight. The best way to manage fire blight is to plant resistant cultivars. Therefore, plants that have been heavily pruned or fertilized with nitrogen (which promotes new growth) are more susceptible to fire blight infection. Young, succulent shoots are susceptible to infection. The wounds can be caused by insects feeding on the plants (they can also spread the bacteria) as well as damage from pruning, wind, and hail. Infection can also occur via wounds on the plant.

Insects, such as flies and bees, that feed on the bacterial ooze may transport the bacteria to flowers as they visit and pollinate them. The most common way the bacteria enter plants is via the flowers. The bacteria can also be spread by splashing rain and wind. Insects are attracted to this ooze and will spread it. When conditions in the spring become warm (around 65☏) and wet, the bacteria will begin to multiply and ooze out of the cankers. The bacteria will overwinter along the margins of cankers in infected plants.