Bacterial desease

Question 1

Describe grapevine yellows.

Answer 1

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
• Most common type is Flavescence dorée found in France, Germany, southern Europe, New York State and, in a different form, in Australia

Question 2

Symptoms of grapevine yellows.

Answer 2

• 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 3

Two varieties vulnerable to grapevine yellows?

Answer 3

• Chardonnay
• Riesling

Question 4

Management options for grapevine yellows?

Answer 4

• No control of the disease itself
• 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 5

Two other bacterial diseases

Answer 5

1. Bacterial blight
2. Crown gall

Question 6

Describe Pierce’s Disease?

Answer 6

A bacterial disease that quickly kills vines

• Bacterium lives in the sap channels of vines, which it clogs, leading to shrivelling, dropping leaves and the death of the vine between one and five years
• Spread by Sharpshooter insect. Glassy-winged sharpshooter has led to the disease spreading rapidly

Question 7

Two varieties that are vulnerable to Pierce’s Disease

Answer 7

Chardonnay

Pinot Noir

Question 8

What are the management options for Pierce’s Disease?

Answer 8

• No chemical control for the disease itself
• 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