Fire Blight

Carol Pinnell-Alison, Thornton, Amy

The disease Fire Blight is more prevalent this year. Fire Blight is a bacterial disease caused by Erwinia amylovora. It infects plants in the pome fruit subgroup of the rose family. Plants commonly infected in the landscape are apple, pear (fruiting and ornamental), mayhaw, Pyracantha and Indian hawthorn. For an infection to occur the host plant needs to be present, the disease organism and the correct environmental conditions. The bacteria overwinter in cankers from the previous year’s infections. The bacteria are spread by splashing water usually from rainfall or by insects. Environmental conditions suitable for disease development include humid or rainy weather with temperatures ranging from a low of 55 ⁰ F at night to a high of 75-85 ⁰ F during the day.

Symptoms of the disease include wilted flowers and flower stems that turn black or brown. The disease will progress to twigs and branches that will wilt forming a “shepherd’s crook”. Eventually they turn black giving the scorched appearance of the plant as the disease’s common name implies.

Management of the disease is through several practices. Plant a resistant variety and use good cultural practices to maintain a healthy plant. Overfertilization and watering that promote lush growth makes the plant more susceptible to the disease. Chemical control is limited since the disease is a bacterium. Pruning to remove infected plant material can reduce inoculum. When pruning make cuts below the infected tissue and disinfect the pruning tools with a 10 percent solution of bleach or other disinfectant often so not to spread the disease.

Fire blight on a pear treejpg

Pear tree with fire blightjpg
Fire Blight damage on Bradford pear

5/25/2020 8:12:39 PM
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