DISEASE

NAME
Citrus Scab
Sphaceloma fawcettii var. scabiosa


Description
Pathogenic, Fungal

Symptoms
This fungus attacks leaves, twigs and fruit. It is most obvious on the fruit surface where it forms scabby areas that may develop into wart-like outgrowths and the tree may shed the young fruit prematurely; persistent fruit becomes larger in size. The leaves develop brown-pink scabby raised areas and may become distorted. Occasionally the fungus attacks the twigs causing dieback and eventually changing the habit of the tree.

     

Source and Dispersal
The fungus overwinters in scab lesions that are found on the twigs and leaves and the spores are dispersed by wind, water and insects. It is also spread by infected plant material.

Favoured Conditions
Infection occurs when a dry period is followed by wet weather predominately in coastal regions. Immature tissue is attacked during blossoming or when the petals fall in spring or autumn.

Affected Plants
Citrus species, particularly lemons.



Non-chemical Control
There is no effective non-chemical control; infected material can be pruned from the plant in order to contain. Dispose of infected material off site.

Chemical Control
Preventative spraying of fungicides is required. Bordeaux, copper oxychloride or zineb should be used before the next crop, at half petal stage in spring or during the second crop in late summer. If symptoms of scab are seen then it is too late to apply chemicals.
Note
Always read the label for registration details and direction of use prior to application of any chemicals.