Various pests and fungal spores are responsible for brown discoloration on juniper. But incorrect care measures can also lead to the leaves and shoots of the trees dying off and looking ugly.
Brown spots are often an indication of disease or pest infestation
Possible causes:
- juniper leaf miner
- pear grating
- Irregular watering
juniper leaf miner
Between May and June, these moths lay their eggs, whose larvae bore into the tips of the shoots. They feed on the pith of the needle-shaped leaves and ensure that the foliage dies off over time. It turns brown starting from the tips.
The larvae pupate in the tunnels and hibernate there until the following spring. To detect a leaf miner infestation, pinch off a brown shoot. A hollow interior or interior filled with crumbs of droppings is a sign of a pest infestation.
combat
Juniper leaf miners are controlled during flight. Shake the branches between May and June to spot the insects. The shimmering golden to brownish colored insects fly up briefly, only to settle down again quickly on a branch. Preparations with the active ingredient pyrethrin have proven to be effective. It is obtained from the flowers of various species of the Tanacetum genus and is considered harmless to bees.
pear grating
This rust fungus uses the juniper as an intermediate host to overwinter. The fungus causes nodular swellings on the branches and leaves. If the fungus is severe, the needles will turn brown.
In the spring, the spore beds can be seen as orange-colored outgrowths, the consistency of which is reminiscent of a jelly-like mass. They swell in humid weather and shrink in dry weather. The spores spread with the wind and colonize the leaves of pear trees. The Chinese juniper is particularly endangered.
combat
As soon as you recognize the rubbery spore bearings, you should generously remove affected shoots and dispose of them with household waste. If the bushes are heavily infested, only complete removal will help. It is better to opt for a resistant species such as Juniperus communis.
Irregular watering
Juniper has a moderate water requirement. It grows in dry locations and only needs occasional watering. Waterlogging causes the roots to die off, causing the leaves to turn brown. Particularly long drying times also lead to brown discolouration.