8.4 Bacterial Disesases

Question 1

What is Pierce’s Disease?

Answer 1

A bacterial disease that quickly kills vines

• Bacterium lives in the sap channels of vines, which it clogs, leading to shriveling, dropping leaves and the death of the vine between one and five years
• Symptoms are unclear

Question 2

Name 2 varieties that are vulnerable to Pierce’s Disease.

Answer 2

Chardonnay, Pinot Noir

Question 3

How does the bacterium that causes Pierce’s Disease spread?

Answer 3

• Sharpshooter insect (vector)

- The glassy-winged sharpshooter has led to the disease being spread more rapidly from the 1980s

Question 4

What are the management options for Pierce’s Disease?

Answer 4

• No chemical control
• Reduce the number of the vector.
  1. Removing vines close to rivers has been effective as riverbanks can be a habitat for one of the vectors (blue-green sharpshooter)
  2. Some chemical insecticides can also be used.
  3. Introducing a species of wasp that feeds on the eggs of sharpshooters
• Strict quarantine rules for the movement of plants
• Future development of Pierce’s Disease-resistant vines

Question 5

What are grapevine yellows?

Answer 5

A group of diseases caused by a type of bacteria that live in a range of plants, including cover crops used in vineyards
- No treatment

Question 6

What is a vector?

Answer 6

An organism that transmits a disease

Question 7

How are grapevine yellows spread?

Answer 7

• Vectors

- Nurseries selling untreated, diseases stock

Question 8

What is the most common type of grapevine yellows? Where is it common?

Answer 8

• Flavescence dorée

- France, Germany, southern Europe, New York State and, in a different form, in Australia

Question 9

What are the symptoms of grapevine yellows?

Answer 9

• Delayed budburst
• A drooping posture because the new shoots fail to become woody
• The canopy turning yellow (in white varieties) and red (in black varieties)
• Sometimes death
• Sometimes recovers after the attack

Question 10

Name 2 varieties that are vulnerable to grapevine yellows.

Answer 10

• Chardonnay

- Riesling

Question 11

What are the management options for grapevine yellows?

Answer 11

• No control
• Controlling the vector:
  1. Insecticides
  2. Removal of plants that host the vectors
• In the nursery, bathe the pruning wood in hot water to kill the disease

Question 12

Name 2 other bacterial diseases.

Answer 12

1. Bacterial blight

2. Crown gall