Virus free scion wood?

I am not well versed in this topic so I will be researching it over the Christmas holiday, but if someone else already has a good factual base I am all ears (or in this case eyes).

What are your experiences with virus sensitive root stock and the grafting of scions to it? Do virus’ in trees express themselves in some visual manner or is the only way to know if the tree your collecting scion wood from is virus free to have a lab test it? Can trees that are deemed clean by a lab contract a virus at a later date? I am planning to graft some trees to one of the Geneva root stocks that is virus sensitive, and just wonder if it is worth my time to do so?

In a world full of viruses nothing is sure. Even experts cannot isolate viruses sometimes when they know exactly what they are looking for eg. stony pit
We all fear it because once your orchard has it the likelihood of getting rid of it is highly unlikely. As your aware ARS GRIN had a virus last year so I ask you if they are 100 times better than us at detecting viruses and yet they had one how safe are we from getting a virus?

Sometimes you can see virus es manifest themselves in the leave coloration- speckled yellowing(mozaic virus), but it is very hit or miss to detect it without lab work.
I think that the virus sensitive Geneva rootstocks will have graft union issues down the line if the scion is infected.
Tissue culture is how they can clean up a variety of infection by heating the apical meristem past the viruses tolerance-ain’t science great?
Not much help to your situation, I’d say short of ordering in certified virus free scions you should just go for it and choose healthy donor trees.
Also, if you are grafting different varieties, it would be worthwhile to sterilize your knife between varieties so that you aren’t a vector spreading contagion.

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I assume that virus’ can be transmitted amongst trees in an orchard setting? Are there places that sell guaranteed virus free scion wood? Would a tree that was virus free when grafted develop an issue at a later date if it “catches” a virus? I would assume not.

I have seen swelling at the graft union with some varieties on G41. I think Washington state sells virus indexed scion.

IMO; Apple trees do not grow in a vacuum. I think of Kazakhstan with Millions of apple trees totally unmanaged. Aside from large commercial orchards, I’m not sure that viruses that show few symptoms are an issue.

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There was an article in the latest American Fruit Grower about this. It was written for stone fruit though.

Basically the article said to minimize risk, don’t obtain scionwood from backyard trees, control wild hosts. Stuff like that. Nothing earth shattering, but still good advice, especially for you guys who have commercial nurseries or commercial orchards.

I’m pretty careful myself. I believe I’ve only received stone fruit scions from three individuals so far, and one of the trees I ended up cutting down about a year after I made the graft. X disease is the big worry for peaches.

I’ve received quite a bit more pome fruit scions from multiple sources because I have less pome trees.

Adams County requires all their stone fruit budwood (from outside sources) be tested by the National Clean Plant Network facility in Prosser, WA.

There is also a Southeastern Budwood program under the direction of Dr. Simon Scott at Clemson University. They also test stone fruit budwood.

In terms of pome fruit, it’s been discussed before, the popular heirloom orchard on the west coast (can’t think of the guy’s name now) who sold scionwood has some issues with viruses in his wood.

This is exactly what I’d expect of places which hunt heirloom varieties (John Bunker, Catholic Homesteading Movement, etc). It’s just a function of mathematics. The more one trades from untested sources, the higher the risk of getting diseases. Sort of like STDs.

One positive is that most of the communicable diseases for pome fruit don’t seem to impact the trees much.

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Multi grafted trees, common with our types, spread viruses. Put on one infected scion and all varieties on the tree get infected. Then trade with others doing the same.


Olpea I read the same article. I grow a number of antique varieties and I guess unless I wanted to have the material tested their would be no way to know if it was virus infected. I likely will not use this particular root stock next year, but dont want it to be a complete bust either.


I do try to take some reasonable cross contamination precautions but, virus are spread by grafting, pruning, roots crossing and insects like leafhoppers. I would prefer not to have virus in my orchard but, allow me to play devil’s advocate. It might not be a bad thing to have an infected virus resistant variety when the virus mutates or is spread at an accelerated rate because of new insect pressure.

That’s an interesting comment,fruitnut.We could be sabotaging ourselves with our own efforts.
It’s sort of like gambling,a person needs to weigh the risks and calculate how much they could lose.With me,it could be a few trees,but with someone like olpea,there is a lot more to be concerned with.
I do try to graft with wood from people with good reputations, but I guess even Robert Purvis’s supply could be suspect. Brady

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Because viruses don’t seem to have ever been a problem, although I often take wood from very old trees and spread it around, I’ve elected to pretty much ignore the threat except on my nursery trees. Perhaps the best way to deal with it in a nursery if you have space, is to order virus-free trees from other nurseries of varieties you want and use them as mother trees.

I can see doing that, but say you have a single tree with a virus on your property that you dont know about, I assume you would infect your other trees? I dont think it would be practical to have every antique variety tested before grafting. I also do custom grafting so I cant keep every tree quarantined in a separate location during the growing process. I guess the best most practical method is to monitor mother trees and not graft from those that show any symptoms of being unhealthy.

I’m not sure the virus would spread so easily, but perhaps it would. Here we often have seedling trees growing wild or very old trees in nearby property. My hunch is that viruses are simply not usually a huge issue in the home orchard context. I manage hundreds and hundreds of trees at more than a hundred sites and have been doing this in the northeast for 25 years+ and I’m unaware of them being a problem. Perhaps it is more an issue in commercial production where even a slight reduction in productivity could put you out of business. That’s not my world.

Of course, all viruses wouldn’t be equal.

Viruses in the orchard may be spread by dagger nematodes as well as sucking insects. But I think what brought latent viruses (no symptoms other than reduced vigor) to the forefront was some sensitivities of the new Geneva rootstocks to scionwood with latent viruses. This came to light after hundreds of thousands of trees were already planted in orchards when the sensitivities came to light. This seemed to trigger the push to eliminate all latent viruses from any wood being traded or imported.

This has kept us from exporting old Southern apples to places like India, where they would be of great economic benefit. But since most of them have never been virus-indexed, they will never see the light of day there except for a few that managed to be imported and spend two years in screenhouse quarantine.

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That is very interesting. If anyone who reads this has noticed a problem of less than expected vigor from any Geneva root stock trees they used for grafting untested scion wood, please follow up with a comment here.

Also, does anyone know if all of Cummin’s varieties are virus indexed? They are the only reliable source of a wide range of Geneva rootstock trees I know of.

I am seeing swelling at the graft union on G41 with around 15% or 20% of cultivars indicating s possible virus. They are otherwise healthy, and vigorous trees.

I assume that testing my 200 apple varieties for viruses and atempting to eleminate them would be cost and time prohibitive. It would be easer to start from scratch.


I found a couple of papers while researching the last couple of days, but they really havent shed any light that hasn’t already been brought up in the conversation. I think the biggest threat is to the commercial orchards that are all hyped about the Geneva root stocks.I can completely understand when you are planting high density and are looking for the highest production levels that any decrease in production is a significant economic hit. My trees arent destined for that kind of market and my typical root stock choices are not the Geneva series ( I see most are reported not to be virus sensitive anyhow). I just planning on giving G935 a 50 tree trial this year.

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I think a key reason commercial growers are attracted to the Gstocks is for fireblight resistance. That is probably something to consider in your neck of the woods, especially for more dwarfing rootstocks where it can quickly kill whole trees or whole orchards.

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Some trees such as honeycrisp appear virus infected. I purchased my honeycrisp from a reputable orchard so I definitely know they are not any different from other honeycrisp. After a year of suspicion I realized it was due to natural problems with the tree Honeycrisp chloroysis will definitely have you concerned the first time you see it Commercial Production of Honeycrisp Apples in Ontario. Never had a virus yet but that’s the kind of thing that is concerning! It could have just as easily been apple mosaic. I’m equally concerned about bacteria as viruses. Let’s face it even bad fungal diseases are something I could do without! Our native wild cherries and plums are hosts to lots of stone fruit diseases. Viruses are out there so limit your scion sources but remember even being as careful as you can be it could happen. Things like cicada spread bacteria or any disease like wild fire. I experienced the 17 year cicada personally and saw it spread fireblight but thank God is was not a virus.
17 year cicada's woke up hungry
Late season Fireblight

Exactly, I was using M26 which also had a few compatibility issues, but switched to G41 because of fireblight resistance. The dwarf trees are just for my trellised experiment station of an orchard.

@TurkeyCreekTrees G935 sounds like it might perform okay as a free standing tree but, any dwarf apple should probably be supported and irrigated in drought and I doubt most backyard / Wildlife food plot growers want to do that. It’s good you’re thinking about mitigating the spread of disease and I would be interested to hear what you find about the cost and logistics of virus testing. I have been testing the logistics of a small scale nursery selling fruit trees the last few years. I do not see latent viruses as a significant threat to hobbyist or small commercial customers a small nursery caters to. I’m sure any potential risk is outweighed by the work you do in testing and offering location specific proven performers in a way a large scale operation could not do.

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