bacterial canker on prunus

Question 1

what genus are affected?

Answer 1

plum
cherry
peach
apricot

Question 2

what are symptoms of bacterial canker?

Answer 2

swollen area on stem-stem cracking

exudes light brown gum

Question 3

what area is most affected by canker?

Answer 3

angle between branches

Question 4

severe infections do what to a tree?

Answer 4

if it girdles them stem, it causes death of tissues above the infection so foliage browns

Question 5

what time of year can leaves become infected?

Answer 5

may/june

Question 6

what happens to leaves at signs of infection?

Answer 6

dark brown spots develop

the infected are can be blown out by wind giving a “gun shot” appearance.

Question 7

how is the bacteria carried?

Answer 7

mainly by wind, but also splashes of rain droplets

Question 8

how does the bacteria enter the stem?

Answer 8

through leaf scars and wounds in autumn

via developing leaves in spring

Question 9

what are the control methods of bacterial canker?

Answer 9

for plums, plant resistant rootstock and scions

cut out infected tissue then apply a suitable paint

spray in autumn with a copper compound to reduce disease

Question 10

describe the lifecycle of bacterial canker

Answer 10

Autumn: rainsplash spreads bacterial spores
enters woody tissue through leaf scars/wounds

Winter: bacteria over winters, causing cankers and regions of necrosis

spring: rain splash passes bacteria onto newly developing leaves/blossom and lives there all summer asymptomatic.

Summer: some bacteria enter leaf through stomata causing “shot hole” symptoms in leaf ans can affect fruit