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Pyracantha Scab


Pyracantha Scab

Usually appear in

Spring to Autumn.

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Caused By:-     The Fungus Spilocaea pyracanthae


Pyracantha scab is a fungal disease of the blossoms, leaves and fruit of Pyracantha(firethorn), resulting in early leaf fall, loss of flowers and disfigured fruit. It is caused by the fungus Spilocaea pyracanthae, which also attacks Cotoneaster, Eriobotrya (loquat) and Mespilus (medlar) and is similar to Apple Scab caused by the fungus Venturia inaequalis.
This fungus produces ark green/black spots on leaves and twigs from spring until autumn, which causes the leaves to fall early. Brown patches or scabs can appear fruits in the autumn which may also split and fall off.
The fungus overwinter on leaves especially those that remain on the tree over winter and probably also on shrivelled fruit and in pustules on the stems, which then release spores to reinfect new growth in spring. Rich feeding promotes soft, young, more vulnerable shoots and leaves.
The spores are spread by water and to a limited extent by wind, so the disease is more severe under wet conditions.
The symptoms on stems are similar to fireblight caused by the bacterium Erwinia amylovora, but fireblight infection on Pyracantha is more sudden and severe than scab.
Picture from Wikimedia Commons.


There are some fungicide sprays that will cure this scab, but sprays will have to be applied in the spring at bud break and at 7 to 10 day intervals until 2 weeks after petal fall.
Good hygiene is important for control, since the fungus survives winter on infected leaves, fruits and pustules on infected stems. Rake up and burn fallen leaves.
If the infection is not too severe prune out infected areas and fruits. This will reduce flowering the following year, but will help lessen the future impact of the disease.
There are some resistant varieties of Pyracantha that can be grown if needed.

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