Virus on Elm?

[proninyaroslav]

It all started with the fact that in the spring some of the growing points dried out, and the leaves began to turn yellow at the ends of the branches (and not vice versa). I treated it with fungicides and it helped, the leaf fall stopped (my tree history https://www.bonsainut.com/threads/s...-dry-out-and-leaves-are-deformed-on-elm.64620).
But I began to observe how the leaves on the affected branches became chlorotic or patterned, with spots similar to a virus. But, new leaves come out clean, without any spots. I'm afraid of infecting other trees...

 

[Leo in N E Illinois]

I'm surprised no one has commented yet.

To answer your question, unlikely. I would just leave your tree alone and let it grow. This does look like spider mite damage, but after every thing the tree has been treated for already this year, it probably just needs to be left alone outside and allowed to grow.

If the tree is outdoors, spider mite rarely is a problem. Natural predators tend to keep them in check along with rain and the garden hose knocking them back. Mites are mostly a indoor house and greenhouse problem.

Now it is true all plants can be infected by their specific viruses, but if you wipe your tools with 70% isopropyl alcohol between plants, you won't spread the viruses.

Most viruses are plant species specific, except for some of the tobacco mosaic viruses. For example there are 7 viruses that infect blueberries, which are spread almost entirely by mechanical picking machines moving from field to field. Sap from broken branches infects the next bush in the row. Mechanically harvested blueberry fields need to be replaced every 25 years or so due to reduced harvest because of low vigor due to virus load.

Cucumber mosaic virus often transmitted by aphids, tend to be obvious it's first year, then slowly disappears, with no symptoms by third or fourth year. Plants have a mechanisms or defense that eliminates the cucumber virus.

Basically, I would not worry about virus. I think you are seeing left over damage from all the different treatments you have already put your tree through.

Just let it grow.

 

[proninyaroslav]

@Leo in N E Illinois
Thank you very much! Usually the spider mite look a little different on Elm. I haven’t seen a spider mite on it this year (including under a microscope), although I did preventive treatment so as not to spread the virus through sucking insects, I heard about it. This spring there were many treatments on different trees due to various leaf spots. On this Elm, the first symptom was that many growing points withered overnight. Fungicide treatments gave results, but some old leaves acquired this spotting and the first thought that came to mind was a virus. In general, the tree grows quickly and doesn't look sick.

 

[Wires_Guy_wires]

Some fungicides mess with the biology of plants as well, and it could be that some functions are inhibited a little because of it.

 

[Leo in N E Illinois]

In general, brown tips to new leaves and or browning growing tips; the most common cause is allowing the tree to get just a little bit too dry between waterings. If the tree is growing outdoors, or has good air circulation indoors or under glass (fans in the growing area) fungus is not usually the "first thing" one should leap to when one see's brown leaf tips or growing tips. Watering frequency should be looked at first. Alternating between slightly too dry with slightly too wet causes more problems for the appearance or more problems than most realize.

It took me a number of years to learn to relax and not "over treat" at the first sign of less than perfect foliage. Too much and too frequent pesticides and fungicides and over enthusiastic attempts at adjusting nutrition can create more problems rather than solve problems. Relax. Trees grow in nature without human intervention. In a pot, other than adding water, trees should grow with minimal inputs. A little organic fertilizer, such fish lysate,, maybe once a month is all that is needed for nice slow controlled growth that we want out of our bonsai. If you push for rapid growth, the growth tends to be coarse and the tree ends up looking less than refined. We are not forcing tomatoes or marijuana, slow growth is good growth.

So just relax, let the tree grow. It will grow out of its current symptoms, possibly not until next year. Its okay.

 

[proninyaroslav]

wipe your tools with 70% isopropyl alcohol

I have heard the opinion that we should not wipe it, but soak the instrument for 15 minutes. Is it so?

 

[Leo in N E Illinois]

I don't recall reading statistics on effectiveness of wipe versus soak, but I worked in concrete chemistry not microbiology. It is the sap of the previous trees cut that carry the virus that will infect the next tree. The alcohol wipe if used to remove the sap, will be effective, wipes are more easily transported, I often end up doing work at club meetings, study groups and other places away from home where setting up a soak might be difficult. Key with using the wipes is to be careful to remove all the sap on the tool.

I did read that 70% isopropyl alcohol is more effective at killing virus than 90% or lower than 70% assays. So 70% is most effective. I assume ethanol could be substituted for isopropyl alcohol, but I prefer to drink my booze instead. Isopropyl alcohol is inexpensive enough at local pharmacies and health & beauty departments of big box stores.

I suppose a soak is great if you can set it up. But I'd still wipe after the soak in case sap, such as pine sap does not dissolve away in the alcohol. Ficus latex is also really difficult to get off of tools.

 

[Betula1]

Washing tools with soapy water or using normal alcohol hand gel as used during covid is perfectly adequate, then wipe dry.
Or you can use Isopropyl alcohol, Methylated spirits or Rubbing alcohol.
Have you been treating the Elm the same as the Hornbeam which you have also reported problems with on here? If so then overdosing with chemical fertilisers and fungicides may have caused part of your problem.

 

[proninyaroslav]

Have you been treating the Elm the same as the Hornbeam which you have also reported problems with on here?

I didn’t treat it with anything, I fertilized and watered it as usual. The leaves burned 2-3 weeks after flush.The Elm clearly has a different problem.

 

[Paradox]

The alcohol wipes are great for taking with you to workshops, club meetings, etc.

At home, I just keep a paper towel and a bottle of isopropyl on the table and wipe the tools between trees.

15 minute soak isn't necessary

 

[proninyaroslav]

Over time, necrotic areas appear on the discolored leaves. But fortunately the yellowing doesn't affect the young shoots, the tree grows very well.

 

[Betula1]

Could this be what is causing your problem? Dutch Elm disease or Elm Yellows Phytoplasma- a virus like disease of Elms in USA and Europe
Candidatus Phytoplasma ulmi (C. Phytoplasma ulmi) for more info see

Elm yellows (Candidatus Phytoplasma ulmi) - Forest Research

Not present in United Kingdom Notifiable – See ‘Report a sighting’ below Scientific name of causal agent – Candidatus Phytoplasma ulmi (C. Phytoplasma ulmi) ‘Yellows’ is a plant disease caused by a group of organisms called phytoplasmas, which are specialised forms of bacteria. One of these...

www.forestresearch.gov.uk

 

[proninyaroslav]

@Betula1
Judging by the description, it affects the phloem, the branches and roots dry out. So far I have not noticed entire branches dying off. Although it is possible that these symptoms manifest themselves differently for everyone.