Parasite under the bark of viburnum

Question: what parasite does my viburnum affect?

First of all, congratulations for your beautiful magazine that I receive every month! I have a problem to submit to you and for which I have not found answers on the internet. I have 9 viburnum trees that are trees ... one is dying ... I looked to see 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 quite sticky). Also the other plants are barked ... which can be ?? I look forward to an answer to be able to promptly intervene! Thank you very much also on behalf of my plants (almost three meters more).

Pest under the bark of viburnum: Answer: dangerous pests

Gentile Liliana,
I believe your viburnum is suffering from some kind of fungal disease, which is developing below the bark, starting from the roots, damaging the wood of the plants; in general, these are fungi that originate in the soil, when it appears wet and asphyxiated for a long time, causing rottenness to the roots of your saplings. From the roots the mushrooms develop rapidly, living undisturbed below the bark; if indeed it is this type of parasite, there is not much to do for your plants, which will be eradicated and burned, to prevent the fungus from spreading throughout the garden, even on other plants.
To know with certainty 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 smell of a mushroom, like that of the mushrooms.
In fact, not having the possibility of seeing your plants live, before deciding that it is actually a fungus, it is advisable that you consult an experienced gardener, in order to implement the most suitable treatments. It could also be another type of fungal disease, which should be eradicated with copper-based treatments; it could be a fungus that didn't hit the roots, but only the wood, and therefore the removal of the damaged branches could solve the problem completely.
Unfortunately, since there are so many variables and we cannot see for ourselves the problem that afflicts your viburnum, it is not easy to make a certain and definitive diagnosis. When we see plants in the garden showing symptoms that are completely different from those we have observed in our garden, it is always advisable to contact a nurseryman or a gardener, or even an agricultural consortium if we have one close to home, in order to be certain of how to act against 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 to understand with certainty what the problem is.
In fact, it could also be insects, although in this case you should see them, partially removing the bark and lifting it.
The most likely hypothesis is unfortunately that it is a root rot that is developing below the bark, rising from the roots to the apex of the stems; if the infestation has just begun, and is not widespread, it is not necessarily said that the only method to eradicate it consists in suppressing plants.