What category of plant pathogens infects plants and is typically rod-shaped with flagella?

• A. Bacterium
• B. Virus
• C. Fungi
• D. Algae

Answer: (A)

Plant-pathogenic bacteria are often described as rod-shaped and flagellated. These single-celled organisms (prokaryotes) commonly have a cylindrical, rod-like form (bacilli) and use their flagella to move through water films on plant surfaces to reach wounds or openings in the plant. This combination of shape and motility is a hallmark of bacteria that cause diseases in plants. Viruses lack cellular structure and do not have flagella, fungi are typically filamentous or yeast-like, and algae, while sometimes motile, are not the classic rod-shaped, flagellated plant pathogens you’d expect in agricultural contexts. So the best match for “typically rod-shaped with flagella” is a bacterium.