Certified Crop Advisor Practice Exam

Which type of pathogens are known to cause discolored mosaics on plants?

1. Bacteria

2. Fungi

3. Viruses

4. Nematodes

The correct answer is: Viruses

Viruses are known to cause discolored mosaics on plants due to their ability to interfere with the normal processes of photosynthesis and plant growth. When a plant is infected with a viral pathogen, the virus disrupts the cellular structure and functioning, leading to characteristic symptoms such as mosaic patterns—areas of light and dark green or yellow—that can often be seen on leaves. This is a result of uneven chlorophyll production and tissue damage caused by the viral infection. While bacteria and fungi can also affect plants, their symptoms typically manifest in different forms, such as wilting, rot, or lesions, rather than the specific mosaic patterns seen with viral infections. Nematodes, on the other hand, primarily cause root damage and can lead to stunting or yellowing but do not typically produce mosaic leaf symptoms. Thus, the distinct feature of discolored mosaics on foliage is specifically associated with viral pathogens.