Question: What parasite afflicts my viburnums?
First of all, congratulations for your beautiful magazine that I receive every month! I would have a problem to ask you and for which I have not found answers on the internet. I have 9 viburnum plants that are trees ... one is dying ... I looked if it had parasites and I saw that the bark of the trunks is eaten and therefore has all the white part exposed (which is also somewhat sticky). The other plants are also barked ... what can it be? I look forward to an answer to be able to promptly intervene! Thank you very much also on behalf of my plants (another nearly three meters).
Parasite under the viburnum bark: Answer: dangerous parasites
I believe that your viburnums are affected by some type of fungal disease, which is developing under the bark, starting from the roots, damaging the wood of the plants; generally these are fungi that originate in the soil, when this is moist and asphyxiated for a long time, causing rottenness to the root system of your saplings. From the roots the mushrooms develop rapidly, living undisturbed under the bark; if it is actually this type of pest, there is not much to do for your plants, which will be uprooted and burned, to prevent the fungus from spreading throughout the garden, even on other plants.
To know for sure that it is a mushroom, you should look carefully at the whitish patina that you see under the bark, it should be silky to the touch, and it should have the mushroom smell, like that of champignons.
In fact, not having the opportunity to see your plants live, before deciding that it is actually a mushroom, it is advisable that you consult an expert gardener, in order to implement the most suitable treatments. It could also be another type of fungal disease, which must be eradicated with copper-based treatments; it could be a fungus that did not affect the roots, but only the wood, and therefore the removal of the damaged branches could completely solve the problem.
Unfortunately, since there are many variables and not being able to see for yourself the problem that afflicts your viburnums, it is not easy to make a certain and definitive diagnosis. When we see plants in the garden that show symptoms completely different from those that we have been able to observe in our garden, it is always advisable to contact a nurseryman or a gardener, or even at an agricultural consortium if we have one close to home, so as to be certain about how to act on the problem.
Unfortunately in a case like this it would be necessary to have at least one sample of the damaged wood, as not even a photograph can help us understand with certainty what the problem is.
In fact, it could also be insects, although in this case you should see them, partially detaching the bark and lifting it.
Unfortunately, the most probable hypothesis is that it is a radical rot that is developing under the bark, going up from the roots to the apex of the stems; if the infestation has started recently, and not widespread, it is not necessarily said that the only way to eradicate it is to suppress the plants.