Like many rose plants, the hawthorn is susceptible to fungal diseases. While plants affected by fire blight usually need to be removed, you can fight fungal diseases like powdery mildew yourself.
The fire blight: Dangerous and notifiable
Like firethorn, hawthorn is susceptible to fire blight. The pathogen is a bacterium that spreads like an epidemic under optimal growth conditions. Fire blight is primarily transmitted by highly infectious bacterial slime, contaminated cutting tools and infected plant material.
You can recognize an infestation with fire blight by the fact that the leaves and shoot tips of the hawthorn turn brown and dry out; they look burnt. The drooping shoot tips of the affected plant are characteristic. As the disease progresses, the contagious bacterial mucus escapes from the branches and leaves.
If you discover fire blight on a hawthorn, you must report this immediately to the State Office for Agriculture. In most cases, the affected trees have to be cleared. It is forbidden to keep bees in the immediate vicinity, as the insects cause the spores to spread over large areas.
Other firethorn diseases:
scab
With this fungal disease, the hawthorn shows brownish spots and cracks on the leaves and fruits. To prevent this, do not plant the hawthorn bushes too closely together so that water on the leaves can evaporate quickly. Cut back diseased parts deep into the healthy wood and dispose of the plant parts in the household waste.
grating
The causative agent of this plant disease overwinters on the juniper and infests the hawthorn every year. The twigs of the hawthorn have orange-colored thickenings in which the spore stores of the fungus are located. Orange-red spots appear on the upper side of the leaves, the veins and petioles are noticeably thickened. Control the plant disease with appropriate fungicides.
mildew
Like all rose plants, the hawthorn is susceptible to powdery mildew. With this plant disease, the leaves of the affected plant have white-grey, milky spots. As the disease progresses, the foliage curls up and the fresh shoots of the hawthorn stun.
In dry and warm weather with nightly dew formation, the entire plant can be covered with powdery mildew in a very short time. The fungus spreads via spores and forms dark winter fruiting bodies in autumn, which overwinter in fallen leaves and fruit.
Remove all infected plant parts and dispose of them in the residual waste. Then treat the diseased plant with a suitable pesticide.
tips and tricks
Fungal spores also adhere to gardening tools, wooden posts, fences and mats for protection against the cold. Therefore, thoroughly clean and disinfect all equipment after contact with the diseased plant.