Michigan State University Extension
Ornamental Plants plus Version 3.0 - 00000468
11/12/99
CRATAEGUS DISEASE PROBLEMS
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.
Cedar hawthorn rust causes orange or rust colored spots on
the leaves (Vis. 1) leading to early defoliation. The
fruits (Vis. 2) and twigs are also attacked. Juniper is an
alternate host. Washington and cockspur hawthorn are
resistant to rust diseases.
Scab causes leaf spotting and defoliation. The fruit
have black raised spots on them.
Powdery mildew causes a white powdery growth on the leaves.
Related information.
Pesticide Recommendations
Bacterial Blights
Hawthorn Leaf Blight
Rust Diseases
Fungal and Bacterial Leaf Diseases
Scab
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This file was generated from data base ZZ on 01/19/00.
Data base ZZ was last revised on 11/12/99.
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