Managemenr of Bacterial Gummosis in Temperate Fruits

1. BACTERIAL
GUMMOSIS OR
CANKER
SUBMITTED TO: DR BHUPESH GUPTA
SUBMITTED BY: RAJAT SHARMA
(H-2017-67-M)

2. INTRODUCTION
– Bacterial canker caused by
 Pseudomonas syringae pv. syringae
 P.syringae pv. persicae causes disease symptoms on peach
and bacterial decline on nectarine, peach and Japanese
plum.
– Bacterial canker is also known as gummosis, because it
causes gumming in infected trees and also as blossom blast,
because it causes blackened wilted blossoms in the spring.

3. BACTERIAL CANKER
– is caused by the bacterial pathogen Pseudomonas syringae pv
syringae.
– Bacterial canker is a disease of the stems and leaves of Prunus,
especially plums and cherries, but also apricots, peaches and
ornamental Prunus species.
– Symptoms:
– stems and spurs: Sunken, dead areas of bark develop in spring
and early summer, often accompanied by a gummy ooze.
– If the infection spreads all round the branch it will die rapidly
– On leaves: Small brown spots appear which are often round
and fall out later to leave holes – as if the leaf had been hit by
shotgun pellets, leading to the popular name of ‘shothole’.

4. SYMPTOMATOLOGY
 Gummosis is a general, nonspecific condition of
stone fruits (peach, nectarine, plum and cherry)
in which gum is exuded and deposited on the
bark of trees.
 Gum is produced in response to any type of
wound, regardless of whether it is due to insects,
mechanical injury or disease.
 Gummosis most commonly occurs as a result of
perennial canker, bacterial canker and the peach
tree borer.
 Gummosis can also be associated with certain
viruses, adverse growing sites, winter damage,
herbicide damage and many other factors.

5. Cankers gradually enlarge until
infected limbs are girdled and then die.
Gummosis is usually associated with
the cankers.
The canker fungi overwinter in active
cankers in living wood or in dead
wood. Infection occurs where the bark
is damaged or injured.
Infection following cold injury
frequently occurs in the crotch angles
of affected trees.

6. CANKER ON
SHOOT

7. – In Peach, Apricot and Nectarine: Damaged areas are slightly
sunken and somewhat darker in color than surrounding bark.
– Cankers have a soured smell.
– The bacterium is a weak pathogen and causes serious damage
only when a tree is in a near dormant condition or weakened
due to unfavorable growing conditions.

8. – In Plum: Cankers develop at the base
of infected buds on trunk and
scaffold limbs.
– In Cherry: Disease outbreaks are
sporadic and more frequent on sweet
cherry than on sour cherry.
– The foliage becomes yellow, curled,
and withered. Wet spring weather
can result in shoot blight and a small
angular leaf spot. This is usually only
a problem in young orchards.

9. DISEASE CYCLE
– Pseudomonas syringae survives in or on plant surfaces, is
spread by splashing rain, and is favored by high moisture and
low temperatures in spring.
– The disease is worse in low or sandy spots in the orchard.
– Vigorous trees are less susceptible to bacterial canker.
– Young trees, 2 to 8 years old, are most affected.
– The disease rarely occurs in first year of planting and is
uncommon in nurseries.

11. MANAGEMENT STRATEGIES
 Several factors must be taken into consideration:
 Orchard sites should not have acidic or sandy soils;
 Trees should be purchased from nurseries known to be free of bacterial
canker;
 Rootstock and cultivar selections should be appropriate for the geographical
area;
 Tree vigour should be maintained by using proper fertilization and irrigation
practices;
 And trees should be pruned to limit chance of spread by pruning in early
summer rather than winter.

12. MANAGEMENT
 Planting trees that are budded or grafted about 32 inches above the root crown
can help suppress bacterial canker infections.
 Bacterial canker tends to mostly affect weak trees, so any management practice
that improves tree vigour (e.g., lighter, more frequent irrigation, improved tree
nutrition, nematode management, etc.) will help to reduce the incidence of this
disease.
 Trees on Lovell peach rootstock are more resistant than others; those on plum
rootstocks are most susceptible.
 Delayed pruning may help.
 In light sandy soils and some heavy soils, successful control has been achieved
with preplant fumigation for nematodes.
 Application of copper during dormancy has not been shown to protect against
bacterial canker.

13. CHEMICAL CONTROL
 Chemical control of bacterial canker is based on sprays with fixed
copper or Bordeaux mixture in autumn and in spring before
blossoming.
– Copper sprays protect initial infection but cannot prevent the canker
phase, once infection has occurred.
 Lovell peach rootstocks are more tolerant to bacterial canker than
most other peach rootstocks.
– ‘Windsor’, and ‘Hardy Giant’ sweet cherry cultivars are susceptible
and should be avoided in disease prone areas. Cherry rootstocks
considered resistant to bacterial canker are F12-1 and Mazzard.

14. – Nematodes stress trees, which predisposes them to
bacterial canker.
• Preplant fumigation for nematode control reduces the
severity of bacterial canker in newly planted orchards.
• The benefits of preplant soil fumigation for control of
bacterial canker usually lasts only a few years; in some
areas only limited improvements in disease control
occur following soil fumigation.

15. RECOMMENDATION
 In Plum: Avoid using high fertilizer rates in late summer.
– Trees showing signs of bacterial canker should be left and pruned after all other
trees have been completed.
 In peach, apricot and nectarine :Avoid using high nitrogen fertilizer rates in mid to
late summer.
– Prune when the trees are fully dormant (January and February).
– High dosage of a copper containing fungicide at leaf drop has been somewhat
successful.
 In Cherry: Use resistant F12-1 Mazzard rootstock.
– Remove girdled branches.
– Spray with copper hydroxide in October and January.

16. • During pruning, do not leave stubs
and avoid a very close flush cut.
• Do not leave weak-angled crotches
when shaping trees as these are
potential sites of infection.
• Apply Mashobra paste after cleaning
the wounds at the time of dormancy
break.
• Spray Streptocycline (20g/100l)
before the onset of rainy season.
• Spray Blitox-50 (0.3%) after leaf
fall.