BACTERIAL BLIGHT Flashcards
1
Q
Also known as
A
Vlamsiekte
2
Q
Causing organism
A
Xanthomonas ampelina
3
Q
Correlation?
A
CLIMATE
4
Q
Where does it occur?
A
All viticultural regions
5
Q
LEAVES
A
- infected directly via stomata (angular brown spots)
- infected from infected shoots (desiccation of leaves or parts of it, from edges inwards, with bright brown necrotic tissue)
- dry out from the margins
- red cultivars: dead tissue is bright brown and separated with a red edge
- yellow edges separate the green parts of the leave for white grapes
6
Q
SHOOTS
A
-bearers won’t bud. the disease is in the wood thus die-back of the vine
7
Q
BUNCHES
A
- distribute in peduncles
- berries and whole bunches can dry out
8
Q
Very susceptible cultivars
A
Palomino & grenach noir
9
Q
Moderately suscpetible
A
Muskadel & Muscat d’Alexandrie
10
Q
How does this disease spread?
A
- bacteria survive during the winter in the sap of an infected vine and are translocated during bud burst to newly developed shoots
- wet conditions (rain or irrigation) aids in the spreading of the disease to neighbouring shoots, leaves and bunches which penetrate through wounds
- because it can survive/move in the sap flow, pruning shears can become infected and during winter pruning spread the disease
11
Q
Typical of bacterial blight?
A
Delayed budburst, development of shoots with short internodes
12
Q
Young shoots
A
lenticular, fine elongated cracks, gradually develop into necrotic cracks and cancers across the entire shoot halves
13
Q
Peduncle and bunches
A
necrotic cracks occur and desiccation/dieback of bunches are initiated
