![]() ![]() The pathogen is most often spread by pollinators as they pick up bacteria from infected flowers and transfer them to neighboring trees. Infection begins in a localized fashion at nectaries and grafting wounds and becomes systemic once the bacteria enter the xylem where they travel through the vasculature of the plant. It affects plants of the Rosaceae family, particularly apples and pears. It is rod-shaped and flagellated, capable of causing infection through the nectaries in flowers and wounds. Often times, infected tissues will exude an amber colored bacterial ooze.īIOLOGY: Erwinia amylovora is a Gram-negative member of the Enterobacteria family. The underlying wood will become discolored. When branches are infected the bark will appear water soaked. Infected shoots turn black and curl giving a ‘Shepherd’s Crook’ appearance. Infected leaves will have a blackened midvein and will eventually shrivel and die while remaining on the tree. These infected tissues will eventually turn black. Symptoms include water soaking on the petals, peduncle, and ovary. SYMPTOMS: Symptoms of fireblight can appear on flowers, buds, shoots, leaves, and mature stems and branches. The recommended type of pruning for this disease is called Ugly Stub Pruning.SCIENTIFIC NAME of causal agent: Erwinia amylovora ![]() Leave a 4-5 inch stub that can be pruned off over the winter when the disease is dormant. Don’t prune infected shoots back to a healthy branch. Infected branches should be pruned 8-12 inches below any visible symptoms.Fungicides that contain copper can be applied at bloom to slow down infections.Avoid cultural practices, such as over-fertilizing, that encourages excessive succulent growth, which is more susceptible to infection.Disease management often involves selecting resistant plant varieties.The disease-causing bacteria overwinter at the margins of cankers and become active again in the spring.The most common insects that spread the disease are pollinators such as bees and flies.During wet weather droplets of bacterial ooze form on the surface of cankers and can be spread by wind, rain, birds, humans or insects to other plants.The most damaging cankers are those formed on the main stem or base of the plant since they often girdle and kill the plant. ![]() The color of the infected wood beneath the bark is often a reddish-brown.With few exceptions, the disease moves more slowly in woody tissue and often moves down to the base of a branch where it forms a lesion or canker.This gives the appearance of scorching as if by fire. The affected leaves turn a dark brown to black and remain attached to the branch. The very tips of the branches often droop or characteristically curl over to give a hooked appearance.The disease progresses from the blossoms into the twigs and branches.The first symptoms usually start on the blossoms as they quickly droop, shrivel or turn brown.Additional plants that can be infected include chokeberry, kerria, photinia, serviceberry, and spirea. However, the list of susceptible plants includes over 130 plant species. The most commonly damaged plants in the landscape are apple, cotoneaster, firethorn, hawthorn, quince, and pear (including Bradford pears).Fire blight is a serious bacterial disease of plants in the rose family. ![]()
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