Jul 17, 2020
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Maybe you have a fruit tree in your yard, apples or pears? Have you started to notice the leaves turning brown, or even black, and your twigs, blossoms and fruit spurs dying? You might be experiencing fire blight.
Fire blight (Erwinia amylovora) is a bacterial infection that affects plants in the Rosaceae family. It is most common in pome type fruits such as apple, pear, and quince. It can also affect crabapple, Pyracantha, roses, cotoneaster, and several other plants. Fire blight begins in spring, when small cankers appear and start to ooze a light-colored tan sap. The cankers form on dark-colored wood that was infected the previous year. The bacteria typically enters the tree when the plant is blooming, and sometimes only affects the flower clusters, but can quickly travel through the new shoots, causing the stems to wilt and turn dark brown or black. This coloration looks to be scorched by fire, hints the name- Fire blight. Look for the afflicted stems forming a “shepherds hook” type of curvature at the tip. The rest of the branch will have a sunken, withered appearance as well.
The best time to treat for fire blight is in mid-winter. On apples and pears look for dark, sunken areas on branches and stems. We cannot stress the importance of sterilizing your pruning equipment enough! A mixture 10% bleach in 90% water is sufficient. Make sure to dip your pruners in the solution between each cut to inhibit the bacteria from spreading. When dormant pruning, locate all infected sites. Trace the branch back to its point of attachment and cut at the next branch juncture down. On main branches, at the site of infection go down into at least 8”-12” of healthy tissue and remove. Once again, sterilize your pruners in between each cut. Remove all afflicted stems and branches and dispose of them properly. It’s recommended that they are burned, do NOT add them to your compost pile! If you have a safe area to burn, this would be the best disposal option. Next, spray the tree with dormant oil to help control fungal spores and insect eggs from the previous year. As the tree starts to bloom, apply Fertilome Fire Blight Spray to your trees in intervals according to the instructions on the label, through the rainy parts of spring. The bacteria spreads by wind, rain, water splashes, birds, and other pollinators.
An ounce of prevention
Good cultural practices can make all the difference when growing fruit trees. Sterilizing your pruners between cuts and removing dead branches and leaves and fallen fruit is a great way to limit the number of pathogens around your trees. Removing the infected branches to help control the spread of the bacteria is of vital importance. It’s also important to remove any sucker branches from the tree, as they are fast growing and prone to infection. Feeding with a low nitrogen fertilizer is important as well, the excessive amount of new growth can be susceptible to infection.
If you are experiencing Fire blight and concerned about your trees, Colonial Gardens has experts who are here to help!