crown gall

Question 1

CG type of organism

Answer 1

bacteria

- agrobacterium tumefaciens

Question 2

CG mode of transmission

Answer 2

• indirect contact
• from the movement of infected soils, plant materials, tools
• travels through soil and water
• lives in soil and water then enters the land through a wound

Question 3

CG symptoms, impact on host

Answer 3

• galls are roundish and rough
• first a cream/green colour then turn brown or black
• galls enlarge
• sever infection can stunt growth and kill plant
• prevents uptake of water or nutrients

Question 4

CG management / prevention

Answer 4

• disinfect garden tools, treat seeds/seedlings
• cut off large galls and disinfect wounds
• remove infected plants
• protect abasing injury
• avoid replanting for a period
• treat soil
• control root chewing insects

Question 5

CG economic impact

Answer 5

• no cure
• nurseries cant sell infected plants
• orchardist may lose infected trees

Question 6

CG life cycle

Answer 6

1. the bacterium uses its flagellum to swim to the plant
2. bacteria is attracted to the sugars and chemicals released by the wound of the plant
3. invades through the wound in the plant
4. bacteria multiply and spread inter cellularly
5. leads to gall formation
6. bacteria move into the soil from the gall