Most conifers are considered robust, but can still be attacked by various pathogens. Trees of life (Thuja) and spruces are particularly endangered, for example by fungi. Many of the microorganisms affect different species, but some are very specialized.
Brown needles can be the result of an illness or a nursing error
Illnesses caused by location or care errors
In addition to a simple infestation with a harmful fungus or another pathogen, a coniferous tree can also become ill as a result of an unsuitable location and / or incorrect care. The causes are not mutually exclusive, but mutually dependent: many microorganisms prefer to attack already weakened trees that can no longer defend themselves. To prevent diseases, you should avoid these causes in particular:
- unsuitable locations (too much / too little light)
- compacted soil / waterlogging
- dry ground
- long, dry periods of frost in winter
- nutrient deficiency (rare)
- over-fertilization (more common)
Common parasitic diseases
If signs of disease appear on a conifer, they can have various causes. The needles are often affected, turning brown and falling off.
rust
There are various rust fungi, such as pine blister rust and juniper rust (the latter causes the dreaded pear lattice rust in pears), which impede water transport in the trunk and branches. As a result, infected tree parts turn brown and eventually die due to undersupply.
needle tan
Needle browning also causes shoot and branch dieback, which is caused by various fungi. The clinical picture often appears in the spring, when individual shoot tips first turn brown and then die.
root and stem rot
Also known as Phytophthora rot, this disease is caused by the soil-dwelling fungus Phytophthora cinnamomi. Infection occurs mainly as a result of waterlogged soil, with roots rotting first and only later the trunk. A typical sign are spongy, violet spots on both the roots and the trunk.
Pestalotia branch dieback
This is a weak parasite that primarily affects already weakened coniferous trees. Pestalotia funerea causes the tips of the shoots to turn gray.
gray mold
Botrytis cinerea has a wide range of hosts and does not stop at conifers. Infection occurs mainly in cold, damp springs and causes the young, still soft shoot tips to turn brown.
tips
Some diseases only affect certain types of coniferous trees, while not affecting neighboring trees. The cause is microorganisms or pests that have specialized in certain hosts. A typical example is the pine shed, where much of the needles are shed.