Bacterial Gummosis or Canker of Stone Fruit

Pseudomonas syringae pv. syringae

Description:

A bacterial disease that enters the plant via wounds or damaged areas from autumn to spring when the trees are dormant. New shoots and branches may wilt and die, cankers may be produced and gum may be exuded from the trunk and branches. Fruit often develops dark sunken lesions.

Species Affected:

Stone fruit.
Apricots and Cherries are highly susceptible.
Nectarines, Peaches and Plums and susceptible.
Of the Cherries, Florence, Napoleon, St Margaret and Williams Favourite are most highly susceptible whilst the Merton types, Ron's Seedlings and Van are the least susceptible varieties.

Biology:

The bacteria are always present on the leaves on many plants.
Actively growing trees are resistant to infection.
Hailstorms, sand blasting, high winds and pruning may cause damage to allow bacteria to infect trees.
Infection may also occur through leaf scars when leaves fall in autumn.
Young trees are more prone to infection than older trees.

Life Cycle:

Origin and History:

Distribution:

Significance:

Management and Control:

Apply fungicides at leaf fall and during winter.
Prune trees in mid summer to early autumn before leaf fall when trees are actively growing so that wounds may heal before dormancy.
Avoid damaging trunks and branches with mowers and other machinery.
Remove and burn infected branches during summer.
Disinfect secateurs and saws frequently.
Avoid overhead watering.
Remove and replace infected young trees.

Related and Similar Species:

References:

1291

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.HerbiGuide.com.au for more information.