Bacterial Diseases

Question 1

Describe Pierce’s Disease.

Answer 1

A bacterial disease that quickly kills vines.

• bacteria 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, and the glassy-winger sharpshooters has led to the disease spreading rapidly

Question 2

Two varieties prone to Pierce’s Disease?

Answer 2

• Chardonnay
• Pinot Noir

Question 3

What are management options for Pierce’s Disease?

Answer 3

• 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 sharpshooter eggs

• strict quarantine rules for the movement of plants
• future development of PD-resistant vines

Question 4

Describe grapevine yellows.

Answer 4

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 doree, found in France, Germany, southern Europe, NYS, and in a different form, in Australia

Question 5

Symptoms of grapevine yellows?

Answer 5

• 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 from the attack

Question 6

Two varieties susceptible to grapevine yellows?

Answer 6

• Chardonnay
• Riesling

Question 7

Management options for grapevine yellows?

Answer 7

• no control of the disease itself, but control the vector:

1. insecticides
2. removal of plants that host the vectors
3. in the nursery, bathe the pruning wood in hot water to kill the disease

Question 8

Two other bacterial diseases?

Answer 8

1. bacterial blight
2. crown gall