Fire blight is characterized by which sign?

Fire blight is characterized by which sign?

• A. A milky white amber droplet of bacterial ooze that may exude from plant parts. Cambial tissue is killed in the region of the canker and will be brown to black.
• B. Caused by several different genera of fungi and commonly infects dogwoods, crabapples, roses and lilac.
• C. Controlled by mechanically severing root grafts.
• D. A disease caused by a virus.

Answer: (A)

Fire blight is a bacterial disease, and a distinctive sign is the ooze that exudes from infected plant parts. The milky white amber droplets of bacterial ooze are produced by Erwinia amylovora as it grows and oozes from cankers and diseased tissue, especially during warm, wet weather. At the same time, the cambial tissue around the canker dies, so you see brown to black necrotic tissue in that region. This combination—visible ooze from cankers plus necrosis of the surrounding cambium—is how the disease is recognized. The other statements describe different problems (a fungal disease affecting various ornamentals, a technique for managing grafts, or a virus-related disease), which do not match fire blight’s signs.

Fire blight is a bacterial disease, and a distinctive sign is the ooze that exudes from infected plant parts. The milky white amber droplets of bacterial ooze are produced by Erwinia amylovora as it grows and oozes from cankers and diseased tissue, especially during warm, wet weather. At the same time, the cambial tissue around the canker dies, so you see brown to black necrotic tissue in that region. This combination—visible ooze from cankers plus necrosis of the surrounding cambium—is how the disease is recognized. The other statements describe different problems (a fungal disease affecting various ornamentals, a technique for managing grafts, or a virus-related disease), which do not match fire blight’s signs.