The first noticeable symptom of fire blight is the browning of branch tips. The tips appear to be burned or scorched and the leaves droop but hang on the tree. Cankers form and the bacteria is washed farther down the branch by rain. The bacteria is spread from diseased to healthy twigs by bees. There is no satisfactory chemical control. Prune out blighted branch tips by cutting well beyond the diseased wood. High nitrogen fertilizer may increase tree susceptibility to fire blight.
Leaf blight caused by Fabraea thuemenii attacks most hawthorns but especially English hawthorn. The symptoms are small reddish brown spots on the leaves which may run together. Infected leaves drop in August and severely infected trees may be completely bare. Sprays of basic copper sulfate may be used on this and other leaf spots.
Cedar hawthorn rust causes orange or rust colored spots on the leaves leading to early defoliation. The fruits and twigs are also attacked. Juniper is an alternate host. Washington and cockspur hawthorn are resistant to rust diseases. No chemical controls are listed.
Scab causes leaf spotting and defoliation. The fruit have black raised spots on them. No chemical control is listed.
Powdery mildew causes a white powdery growth on the leaves. Spray with benomyl when the disease is first noticed.
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|Cedar hawthorn rust on hawthorn - 47K|