Various pests and fungal spores are responsible for brown discoloration on the juniper. But incorrect care measures can also cause the leaves and shoots of the trees to die and look unsightly.
Why is my juniper turning brown and what can I do?
Brown discoloration in juniper can be caused by juniper leaf miners, pear rust or irregular watering. To resolve the problem, identify the cause and control pests or fungi accordingly, or adjust the water supply.
Possible causes:
- Juniper Leafminer
- Pear grid
- Irregular watering
Juniper Leafminer
Between May and June, these butterflies lay their eggs, the larvae of which bore into the tips of the shoots. They feed on the pith of the needle-shaped leaves and ensure that the foliage dies over time. It turns brown starting from the tips.
The larvae pupate in the corridors and overwinter there until the next spring. To determine an infestation by the leaf miner, you must pinch off a brown shoot. A hollow interior or one filled with fecal crumbs is a sign of a pest infestation.
Combat
Juniper leaf miners are controlled during the flight period. Shake the branches between May and June to detect insects. The shimmering golden to brownish colored insects fly up briefly and quickly settle again on a branch. Preparations with the active ingredient pyrethrin (€9.00 on Amazon) have proven to be effective. It is obtained from the flowers of various species of the genus Tanacetum and is considered harmless to bees.
Pear grid
This rust fungus uses the juniper as an intermediate host to overwinter. The fungus causes knotty thickenings on the branches and leaves. If there is severe fungal infestation, the needles turn brown.
In spring, the spore beds are visible as orange-colored outgrowths, the consistency of which is reminiscent of a gelatinous mass. They swell in wet weather and shrink in dry weather. The spores spread with the wind and colonize pear tree leaves. The Chinese juniper is particularly at risk.
Combat
As soon as you recognize the rubbery spore deposits, you should generously remove affected shoots and dispose of them with household waste. If the bushes are severely infested, only complete removal will help. It's better to choose a resistant species like Juniperus communis.
Irregular watering
Juniper has moderate water requirements. It grows in dry locations and only needs to be watered occasionally. Waterlogging causes the roots to die and the leaves to turn brown. Particularly long drying times also lead to brown discoloration.