Symptoms
This
is a serious disease of Pyracantha or
firethorns, grown particularly for their berries.
Dark green to black spots appear on leaves and twigs in early summer, causing leaf fall. Scabby patches appear on fruits later in the autumn, spoiling their appearance. The berries may also split and fall off.
The disease can be confused with fireblight, which also occurs on Pyracantha; however, fireblight causes a more sudden wilting and shrivelling of the shoots.
Biology
This disease is caused by the fungus Spilocaea pyracanthae. It is found particularly during damp conditions. It overwinters on diseased leaves remaining on the plant, and as pustules on the shoots.
Non-chemical control
Prune out and dispose of infected twigs. If done early in the year, pruning will reduce colonisation of the later flowers and berries and prevent the disease overwintering.
Chemical control
There are no fungicides available to amateur gardeners specifically for control of this disease. However, the fungicides myclobutanil (e.g. Systhane Fungus Fighter) and penconazole (Scotts Fungus Clear) are approved for control of other diseases on ornamentals and may give some control.
Cultivars showing some resistance
Resistance is not complete and varies with the local conditions
and over time.
Pyracantha rogersiana ‘Saphyr®’
range (several cultivars), ‘Shawnee’, P. gibsii ‘Golden Charmer’,
‘Navajo’, ‘Orange Charmer’.