B6.3.5

Question 1

Example of a viral plant disease

Answer 1

Tobacco mosaic virus

Question 2

What are the symptoms of tobacco mosaic virus

Answer 2

It attacks leaves making them mottled or discoloured by preventing chloroplasts from forming, stunting the growth of the plant.

Question 3

How is tobacco mosaic disease prevented from spreading

Answer 3

Plants should be removed and hands and equipment washed between planting. Crops that are resistant to the virus should be planted on the previously affected area.

Question 4

Example of a bacterial plant disease

Answer 4

Agrobacterium tumefaciens

Question 5

What are the symptoms of Agrobacterium tumefaciens

Answer 5

It causes the production of large tumour like growths called galls. As the disease progresses the galls can encircle the plants stem or trunk cutting of the flow of sap. Causing stunted growth or death.

Question 6

How is Agrobacterium tumefaciens stopped from spreading

Answer 6

Infected plants must be destroyed and removed. Planting other susceptible plants in the area should be avoided for the next 2 years.

Question 7

Example of a fungal plant disease

Answer 7

Powdery mildew

Question 8

Symptoms of powdery mildew

Answer 8

Infected plants displays white powdery spots on the leaves and stems.

Question 9

How are the symptoms of the fungal disease

Answer 9

It reduces growth and makes leaves drop of early.

Question 10

How is powdery mildew stopped from spreading

Answer 10

It can be controlled by spraying the crop with fungicide.