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.

Plant growth regulators may be used to slow vegetative growth rates.Natalie P.

Avoid overuse of materials that can lead to the development of resistance in this pathogen.

Apply antibiotic sprays at bloom to help prevent the disease from becoming established in an orchard.

Use biological control materials in conjunction with antibiotic materials to reduce resistance development.

Apply recommended fungicides at the green tip stage to reduce the amount of inoculum on the outer surfaces of infected trees.

Dormant to early season copper applications reduce epiphytic bacterial populations.

Refer to the New England Tree Fruit Management Guide for specific materials and rates recommended for managing Fire Blight.

When removing infected plant material during the growing season, prune only on sunny, hot days when rain is not predicted.

When removing infected plant material, cut infected branches at least 12 - 18” below the lowest evidence of disease.

Inspect orchards weekly in the summer for fresh infections and remove.

Maintain proper orchard nutrition in order to discourage excessive tree vigor.

Avoid more susceptible cultivars when planting new orchards.

Removal of cankers during dormant pruning.

Infection is most likely to occur after 200 degree days (base 65˚F) have accumulated since the first blossom has opened in the orchard. The need for chemical control depends on a combination of orchard risk factors and weather conditions during bloom. This model measures temperature, rainfall and leaf wetness to determine the risk of blossom, canker, shoot and trauma blights. Instead, monitor infection risk potential using disease forecast models such as Maryblight, developed at the University of Maryland. Monitoring: As with most pathogens, monitoring for physical signs of bacteria is impractical. Secondary infection arises from ooze from fresh infections. The bacteria penetrate the tree at natural openings or wounds. In the spring when temperatures begin to warm, the cankers exude a characteristic ooze, and the bacteria are disseminated by rain and insects to vulnerable tissues - especially open blossoms, tender vegetative shoot tips, and young leaves. The bacteria overwinter in bark tissues along the edges of cankers caused by infection in previous years. Fruits affected later are less shriveled and discolored and often ooze inoculum. They will remain attached to the cluster. Fruits infected early remain small and appear shriveled, dark, and ‘water soaked’. This is especially true for high density plantings as these trees tend to be smaller allowing the bacteria to move rapidly through the whole plant. Affected vegetative shoots wilt, causing the distinctive shepherd’s crook appearance. As the pathogen progresses in its host, the tissue blackens, appearing as if burned. Varieties differ in their susceptibility to Fire Blight.

Infection in some cases can lead to tree death. Applications of Apogee or Kudos for shoot blight may be made during active shoot growth.įire blight is a destructive disease of apples and pears that affects blossoms, fruits, shoots, and limbs.

Chemical control begins with a copper spray at silver tip to green tip. Monitor weather data and use a forecast model to determine the need for antibiotics and biopesticides at bloom.

Sanitation is accomplished by removing blighted shoots and whole trees.Fire bight management is a combination of tactics applied every year.Bacteria then migrate through the vascular tissue to the growing shoots and rootstocks killing tissue and whole trees. Infection of blossoms occurs during warm weather in conjunction with wetting events.Outbreaks in New England are sporadic, but have become more common in recent years. Fire bight (FB) is caused by the bacterium Erwinia amylovora.Apple - Fire Blight ( Erwinia amylovora) Overview

Fire blight of apple