16. What is the primary mode of transmission for viral diseases in plants?
a) Soil
b) Wind
c) Water
d) Insects
Answer: d) Insects
17. Which of the following is a bacterial disease affecting grapes?
a) Late blight
b) Black rot
c) Citrus canker
d) Downy mildew
Answer: b) Black rot
18. What is a common symptom of clubroot in plants?
a) Yellowing of leaves
b) Wilting
c) Swollen and distorted roots
d) Black spots on leaves
Answer: c) Swollen and distorted roots
19. Which of the following is a viral disease affecting potatoes?
a) Late blight
b) Potato leafroll virus
c) Tomato mosaic virus
d) Anthracnose
Answer: b) Potato leafroll virus
20. Crown gall is a bacterial disease that affects which part of the plant?
a) Leaves
b) Stems
c) Roots
d) Fruits
Answer: b) Stems
