What is the apple scab pathogen best described as?

What is the apple scab pathogen best described as?

• A. Symptoms appear as velvety, olive green spots on leaves; leaves turn yellow and drop off in midsummer; fruits may develop rough, corky, brown spots.
• B. 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.
• C. Controlled by mechanically severing root grants.
• D. A fungal disease caused by rust.

Answer: (A)

Apple scab is a fungal disease of apples. Its most recognizable signs are velvety, olive-green spots on the leaves; as the disease progresses, leaves may yellow and drop prematurely in midsummer. On fruit, scab causes rough, corky brown spots that can affect quality. The other options describe different issues: a bacterial canker outcome with ooze and darkened cambial tissue; a claim about root severing that isn’t relevant; and rust, which is caused by a different type of fungus and presents differently. So the description of olive-green, velvety spots on leaves along with corky brown fruit spots matches apple scab.

Apple scab is a fungal disease of apples. Its most recognizable signs are velvety, olive-green spots on the leaves; as the disease progresses, leaves may yellow and drop prematurely in midsummer. On fruit, scab causes rough, corky brown spots that can affect quality. The other options describe different issues: a bacterial canker outcome with ooze and darkened cambial tissue; a claim about root severing that isn’t relevant; and rust, which is caused by a different type of fungus and presents differently. So the description of olive-green, velvety spots on leaves along with corky brown fruit spots matches apple scab.