Brown spot disease
Affected tree species
mountain pine, Scots pine, Scots pine, black pine
First occurrence
2012
Damage pattern
First yellow, then brown, 1 to 2 mm large spots with yellow edges appear on the needles. Finally, the needles become completely brown and die off. The disease usually starts at the lower branches near the ground and then spreads towards the top of the tree. The disease discolors perennial needles brown from about June. Freshly sprouted needles appear green and healthy at the beginning, they become infected later. In the case of heavy infestation, even the youngest needle vintages can fall ill and the tree dies.
The brown spot disease can be confused with the red band disease, an insect infestation or the physiological needle shed. A microscopic examination is necessary for a clear diagnosis.
Risks
Needle browning results in a strong optical impairment. However, there is no safety hazard. Heavily infested trees can die off completely.
Countermeasures
No countermeasures are known. Because of the danger of the disease, infested plants must be cleared and destroyed. Due to the risk of infection, this measure should not be carried out in damp weather or rain.
Obligation to report
Yes
Boxwoodzünsler
Affected tree species
Boxwood
First occurrence
2007
Damage pattern
Young larvae cause the so-called window feeding. Typical for this feeding pattern is that the lower epidermis of the leaf is left intact, which appears like a window. Later, the whole leaves and even the shoot bark are eaten. As the larvae spin into leaves to moult, an infested boxwood plant often appears sticky. On closer inspection, small caterpillars and excrement crumbs can then be discovered between the leaves.
Risks
Heavy infestation leads to total loss of the plants. Since the European borer produces up to three generations per year in Central Europe and is avoided by predators due to the toxicity of the fodder plant, the pest can multiply and spread explosively.
Obligation to report
No
Horse chestnut leaf miner moth
Affected tree species
Horse chestnut, red horse chestnut, sycamore maple
First occurrence
2000
Damage pattern
From mid-May on, punctiform bright spots appear on the upper side of the leaves, which first enlarge comma-like and finally expand to spots of several centimeters in size. In the course of the summer, these can cover the entire leaf surface, whereby an increasing brown coloration of the damaged tissue also occurs. The "stains" are feeding tunnels caused by the larvae living in the leaves. These are yellowish in color and are strikingly strongly segmented. The larva pupates and a butterfly with bronze colored wings with white bands hatches from the pupa. The butterfly in turn lays eggs on the leaves from which larvae hatch after about 14 days, which in turn eat into the leaves. A total of three (to four) generations are formed each year, with the main flight times being in May, July and September.
Risks
In case of a strong infestation, almost the entire crown can be affected. Heavily infested leaves die and show premature leaf fall, which is why many horse chestnuts are almost leafless from about August onwards. A complete death of a tree solely due to a leaf miner moth infestation has never been observed so far. But the premature loss of leaves will probably weaken the trees in the long term and make them more susceptible to other harmful organisms.
Obligation to report
No
Massaria
Affected tree species
plane tree
First occurrence
2008
Damage pattern
The symptoms are difficult to detect visually from the ground. On the upper side of the branch there is often a stripy red or pink discoloration. The branches turn black in a later stage due to the spores of the fungus. The infestation becomes obvious by partial or complete death of branches of the lower and middle crown. The dying process can proceed very quickly, even with strong boxes, sometimes within a few months.
Risks
Dying and dead branches are prone to break within a few months and therefore represent a high safety risk.
Obligation to report
No