Mosaic Virus in Celtis occidentalis

[rfwoodvt]

Just received a request from a relative living on the Patomac River in Virginia regarding a Celtis occidentalis on thier property.

VA Coop Ext has tentatively identified the problem as Hackberry mosaic virus or Hackberry Island Chlorosis. Having looked at the trees and the samples I have to concur that it is likely one of these viral infections at work.

There are only two shade trees on this property and they are both infected so keeping them going is in order.

I'm going to look at them at the end of the month with the idea of maintenance pruning, root zone aeration and probably some fertilization.

Since VA is a bit out of my normal environment I was hoping to get your thoughts on management and for keeping these trees in a happy place.

Most specifically has anyone encountered these two diseases and how are you managing it?

Also since we are going to punch 2 inch diam aeration holes I wanted to apply a granular fertilizer in the holes.

Anyone have a preferred fert and application rate to use? Note: this is right on the river so I want to be cognizant of phosphorus and Potassium leaching.

 

[TLHamel]

Hackberry Mosaic virus is not uncommon here in the Twin Cities. Does not affect photosynthesis as far as I know (or can see). No treatment for viruses. 'Mulch and water' is what I tell clients... a good mantra for any tree.

Aeration is a good idea if needed. Why apply fertilizer? How is fertilization going to affect the Mosaic virus? Have you done a soil/foliar sample?

 

[guymayor]

[ QUOTE ]
Why apply fertilizer? How is fertilization going to affect the Mosaic virus?

[/ QUOTE ]

It may help it...more succulent growth for the leafhoppers to feed on. maybe better to build up leafhopper predators by diversifying the landscape with shrubs and flowers and encouraging birds.

I like mosaic diseases; like pretty variegation. but if the tree declines then they are no fun.

 

[rfwoodvt]

My thoughts on the Fertilizer center around the transient nature of N in the soil and the overall vigor of the the trees.

Certainly the goal is not to flush a whole bunch of leaves onto the tree but rather give it longer term sources.

I've also been seeing a relationship between N supplementation and root development in several tomes I have read as well as anecdotal evidence in some landscape settings.

Since happy roots = happy trees and vigorous trees can overcome or at least cope with heavier stresses the idea of supplemental N is not so far fetched.

Fact remains, though that N is frequently deficient in soils and supplementation of the right type and amount is prudent.

Arguably the succulent growth, assuming flush growth is achieved, can make it more favorable to the leaf hoppers. but I suspect done right, the increased vigor and reserves the tree can generate will outweigh that concern.

The variegation/chlorosis apparently has not shown to be a detriment to photosynthesis according to several studies.

But everything my reading, and gut have said, is that a reduction in chlorophyll translates into reduced photosynthesis. Especially when the chlorosis seems to be general as opposed to variegated.

These two trees appear to have variegated as well as general chlorosis which both appear to be related to the virus.

Anyhow, that's why I ask the questions...though they may seem weird, wrong or out of place...answers and ideas are bound to be shared here!

 

[banjo]

Why not go with compost in the holes to start building the soil?

 

[guymayor]

[ QUOTE ]
My thoughts on the Fertilizer center around the transient nature of N in the soil and the overall vigor of the the trees.

Certainly the goal is not to flush a whole bunch of leaves onto the tree but rather give it longer term sources.

I've also been seeing a relationship between N supplementation and root development in several tomes I have read as well as anecdotal evidence in some landscape settings.

Since happy roots = happy trees and vigorous trees can overcome or at least cope with heavier stresses the idea of supplemental N is not so far fetched.

Fact remains, though that N is frequently deficient in soils and supplementation of the right type and amount is prudent.


[/ QUOTE ]No arguments here--I am not anti-N, but I am totally pro-associates, following a very smart bug guy, Mike Raupp, who is always talking up a healthy diverse landscape as an excellent pest management system.

 

[Sylvia]

I'm not anti-N either, I just think it might be applied more often than necessary. But that is said without seeing these trees...or having the soil/foliar analysis.

Granted N is one of the harder elements to test for because of its constant mobility and changing forms.

In your first post you mention the concern of P and K and a water source, but now are only talking N. Have you backed up your thoughts on what type of fertilization? Another reason for the soil analysis revealing pH would be to be sure to prescribe an appropriate fertilizer best suited to the type of soil.

I am not familiar with mosaic virus in Celtis or anything else, but what I am reading is there is no cure (I believe TJHamel also said this) and that the jury is still out on whether it is seriously damaging to the host. (Perhaps this is on a case-by-case or species-by-species basis? Could be adding a stressor to an already stressed plant? etc)

The sources I read mentioned potential vectors of leafhopper, aphid, and mites. So I would be cautious about pushing succulent growth.

Without more information and/or site photos, I would be going with the other recommendations of aeration with fully-decomposed compost added, mulch and reviewing irrigation regimen.

Crown cleaning, as in deadwood removal, is always a good idea, IMHO.

Sylvia

 

[guymayor]

Good point on reading the pH, Ms. BCMA. I use a $40 handheld field device. If it reads too acidic for hackberry's comfort zone, then maybe blending lime into your inoculant mix is called for.

"The sources I read mentioned potential vectors of leafhopper, aphid, and mites. So I would be cautious about pushing succulent growth." Rick already said he was aware of this; he won't go crazy with N... So then what about going out with Auntie Em and "pushing" the birds and beneficial bugs by planting beds with shrubs and perennials??

 

[rfwoodvt]

[ QUOTE ]
So then what about going out with Auntie Em and "pushing" the birds and beneficial bugs by planting beds with shrubs and perennials??

[/ QUOTE ]

Well underway! due to the lack of mature trees on her lot (other than the two Celtis) she has done well with a variety of shrubs, ground cover and ornamentals.

They recently replaced the old retaining wall with a terraced and planted retaining wall as well.

Her own micro-environment is certainly improving but being a DC "weekend" suburb on the Potomac means lots of, shall we say, "Tank Fed" landscape maintenance in the surrounding neighborhood.

I think my game plan is going to be Maintenance pruning, vertical mulching, pH adjustment as appropriate and some slow N after the leaves harden off.

When do the spring leaves harden off in that zone Guy? By mid May?

I also want to learn more about viruses and how persistent they are in the tree. Meaning, if we are able to reduce the vectors, would that make any difference since the pathogen is already in the host?

 

[rfwoodvt]

Just received a copy of the soil analysis. As expected the N is low (though lab assays of N are notoriously useless) and the organic matter is very low.

pH is 5.9 so we'll need to adjust that as well and that will be our first step.

I've posted in another category looking for someone with an air spade in the area of the tree so we can radial trench and introduce some compost and milorganite or other such amendment to increase the N.

Plans now are to get the lime down now and radial trench, fertilize and Maintenance prune either mid may or early June.

 

[guymayor]

Not extremely acidic, good. Agree on N and assays; rarely do i get a test back that does not call for it.