Despite its hardy properties, juniper is occasionally attacked by disease. They are caused by various fungi and can be fought well if detected early.
Brown branches often indicate disease infestation
Common diseases:
- dieback
- Juniper bubble grate included
- pear grating and
- Hawthorn grating
dieback
The fungus Phomopsis juniperivora is responsible for this disease. The spores colonize the needles of young plants. These initially turn brown and later yellow-brown to grey. The needles remain and do not fall off. After just a few days, black fruiting bodies can be seen on the dying needles and soft shoots. Dieback can often be seen in Virginian juniper. Affected plant parts should be generously removed and disposed of.
juniper blister rust
Behind this disease are two types of rust fungi that colonize different juniper species. Rust fungi are characterized by a change of host. Different trees and shrubs are required for successful propagation. Combating these fungal diseases is the same for both species.
pear grating
The disease is caused by the rust fungus Gymnosporangium sabinae, which occurs on juniper trees in spring. It is expressed by thickening of the woody shoots. In humid conditions, the spore stores swell into gelatinous blisters. They develop tiny spores that are transferred to the leaves of pear trees in windy weather.
Pear rust preferentially affects:
- Juniperus sqamosa
- Juniperus chinensis
- Juniperus media
Hawthorn grating
This fungal disease is caused by the species Gymnosporangium clavariiforme. The spores prefer to settle on hawthorn between April and September. In the spring there is a change of host. The fungus colonizes the shoots of Juniperus communis and develops tongue-shaped spore beds that glow orange. In damp weather, they swell and have a gelatinous consistency. Under dry conditions, the spore stores lose water and shrink.
control and prevention
In most cases, you can do without fighting, because the majority of all ornamental trees affected survive an infestation with rust fungi well. Affected branches are cut out so that the fungus cannot multiply further. If the infestation spreads from the shoots to the leaves or roses are nearby, you should resort to pesticides.
Regular spraying with horsetail decoction has proven to be a preventive measure. The extract is injected as soon as the leaves sprout. Potassium fertilization can also be used preventively.