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This illness starts with the withering away of some of the conifers branches followed by others. If nothing is done, then the entire conifer will die and even the whole hedge may perish!
The symptoms
The first signs of the disease are often not noticed: the very small branches that are only a few centimetres long begin to dry out here and there, just like a few cut stalks that were left over after pruning. Then the drying out spreads to bigger and bigger branches. At the advanced stage of the disease the whole conifer starts to dry out with only a few remaining branches. It dies shortly after.
Lifecycle
It is a fungus that causes the conifer to perish. The germ of this disease installs itself on a few of the smaller branches that subsequently die: this stage corresponds to the first signs of the disease. Over time, the attacked branches contaminate the healthy ones and the disease spreads through the entire plant. It can take several years between the appearance of the disease and it spreading through the entire plant. However, the progression of the wilting is not inevitable if certain measures are taken to fight it.
How to fight it
As soon as you notice the symptoms, spray the tree with an anti fungal treatment, for example soluble sulphur or bouillie bordelaise solution. You must repeat the treatment after each warm or wet spell, particularly in autumn and the spring, the periods when the disease is at its most virulent. Plant extracts (liquid manure from horsetail extract for example) are not effective against this type of attack.
How to avoid it
Pruned hedges are much more susceptible to this disease than others, because the pruning tools like secateurs or hedge trimmers spread the germs. You must disinfect the tools before each pruning, especially if you borrow or rent them. In addition, the disease develops quicker on conifers that are in an enclosed environment or where there is constant humidity, like hedges that protect a patio and receive all the water that runs off it. In this case, you should choose other plants than conifers to shelter the patio.
Good to know
The sudden perishing of a conifer in the space of a few weeks is due to another disease that attacks the roots: honey fungus. - Photos (1)
Conifer wilt
Conifer wilt
Author: Jean-Michel Groult