Powdery mildew and rusts are examples of which plant disease feature?

Powdery mildew and rusts are examples of which plant disease feature?

• A. Sign
• B. Symptom
• C. Lesion
• D. Canker

Answer: (A)

Powdery mildew and rusts are signs of a disease. A sign is visible evidence of the pathogen itself, not just how the plant is affected. You can actually see the pathogen on the plant: the white powdery growth of powdery mildew and the rust-colored pustules of rusts. That direct observation of the pathogen’s structures is what makes them signs. In contrast, symptoms are the plant’s responses or changes caused by infection, such as yellowing, leaf curling, stunted growth, or necrosis. The other terms—lesion and canker—describe types of tissue damage or disease forms rather than direct evidence of the pathogen’s presence, so they don’t fit as well for these examples.

Powdery mildew and rusts are signs of a disease. A sign is visible evidence of the pathogen itself, not just how the plant is affected. You can actually see the pathogen on the plant: the white powdery growth of powdery mildew and the rust-colored pustules of rusts. That direct observation of the pathogen’s structures is what makes them signs.

In contrast, symptoms are the plant’s responses or changes caused by infection, such as yellowing, leaf curling, stunted growth, or necrosis. The other terms—lesion and canker—describe types of tissue damage or disease forms rather than direct evidence of the pathogen’s presence, so they don’t fit as well for these examples.