HVX, anything change?

[sweetee]

Hi, this question has probably been answered before but there seems to be mixed information. When speaking with people now they are saying only sap to sap contact can spread hvx. In the early days it seems like people were saying everything can spread it, the seed, the water run off ... Just to clarify; can an HVX infected hosta be carried on to the seed. If someone had an infected hosta, took seed and planted, would those seedlings be infected? If water runs out of a container into another, can that spread HVX? . Thanks

[Tigger]

Sweetee,

Researchers have recently found that seeds can contain the virus. That is, the pod-infected parent can pass it on. I don't think there's any evidence that the pollen parent can pass on the virus. I don't recall what the proportion of infected seedlings was.

As to water run-off from plants in pots, it is feasible but a stretch. If water run-off from a recently potted infected hosta, where the roots and/or leaves were (probably inevitably) damaged/wounded in the potting process, ran into the pot of a similarly wounded plant, then that could cause plant-to-plant viral transfer. Maybe this could happen if you had your pots on stacked shelves... I dunno. Certainly in a home garden situation it's not going to be as bad as the water-borne transmission caused by commercial root-washing (with recirculation of wash water) that made the HVX problem explode.

David

[sweetee]

Thanks David, That's what I thought but a reliable source just told me that even if I rec'd an infected hosta in an order, it doesn't mean that the rest are infected, since they said it's only sap to sap. Their take on this was that this is after research, the final conclusion.
That brings up another question. If you have an infected hosta in a bed and remove it, but cannot get all the roots, will all other hosta eventually become infected in that bed? That's even if they test negative now? I really thought I had all of these questions answered a few years ago but now I'm wondering again. Thanks.

[Chris_W]

The chance of another hosta that grows in the same root zone as an infected also becoming infected is something like 10 to 20%. The longer they are in contact the greater the risk over time. If you can't get the infected roots out because of healthy plants nearby then wait until the plants are completely dormant to move the healthy ones out of the way, then dig out the area better and replace the soil before replanting. HVX doesn't move when plants are dormant (it still gets on the shovel but doesn't infect dormant plants). Dig and pry up the healthy plants and then wash off the dirt and any other root material that was around it before replanting.

Unfortunately the last rounds of research didn't use large enough sample sizes to form the definitive conclusions that people drew from it. In past studies done by other researchers it was shown that the transmission rate from simple contact of one plant with another and through handling infected roots and then healthy roots is about 1 to 2%. That was also the rate of infection we saw here in 2004 when we potted up plants that were infected and then potted up plants that were from clean sources. We quarantined all of them and were told that simply handling them wasn't a risk, but about 2 in 100 of the healthy plants potted on the same day showed infection much later. When we did the potting they were all dormant and did not realize the plants were carrying HVX until after they emerged. That was when we started to quarantine and test everything coming in.

HVX is unlikely to spread in irrigation water unless it is a very powerful stream and is moving soil along with it. Soil abrasion into water leading to abrasion in another plant with the same dirty water can move the virus to other plants. Strong storms that wash torrents of water through fields/gardens moving a significant amount of soil has the potential to move the virus, but the transmission rate is unknown.

Hope that helps to answer some of your questions.

Chris

[sweetee]

Thanks Chris;
Coming from a nursing background, I treat it as an infection. I don't cross contaminate. The one I had infected was already removed, but all roots are entangled with tree roots with very little chance of getting them out. Since this is only in one bed I've written off that bed for hosta. I have some hosta in that bed, but nothing rare.
I have thought about taking a division off of the ones which are outside a 2 foot radius of the previous space. Still haven't decided on that but probably will make that decision in Sept.

It's amazing how much conflicting information is out there, even from reliable sources. Since I consider you "Chris the Hosta Whisperer" , I usually listen to you. Thanks much! Sweetee

[Chris_W]

It is technically true that HVX moves sap to sap, but the problem with HVX is that it is highly stable outside the plant, so it can move sap to tool, sap to soil, or sap to hand, and then move tool to sap, soil to sap, and hand to sap. HVX was once thought to be pretty easily controlled and hard to spread, but over the years that hasn't been what the industry and gardeners have experienced.

There are still a lot of people who try to downplay the threat (they used to ignore it years ago) and others who seem to believe what they want to, but that doesn't help get this thing under any better control

[sweetee]

I'm always concerned about my gardening gloves. I am constantly touching my hosta/dirt. I've chosen now to keep some antibacterial gel on my table and I rub it on my rubber gloves between hosta.
Chris, I think the thing that still amazes me is when I ask someone before I buy if they test for hvx and the response I hear is; no, but the place we get them from tests. Is that reliable enough?
I have learned who is reputable and maybe that's how it works, but that just doesn't seem like a reliable method. Any thoughts on this? Thanks, Sweetee

[Chris_W]

We have tubs of disinfecting wipes out in the gardens and the production areas and the shipping area. Everyone here is in the habit of washing their hands and wiping down their gloves. It isn't that we have a virus or nematode problem but prevention is the best protection, and those things can be in a lot of different plants.

The suppliers we buy from say they test or are virus "free", but when I try to get them to give me specifics they aren't able to tell me much or in one case they said they watch for it and destroy any infected plants. That's about the worst thing I've ever heard and they said their plants are virus free, though it is based on visual symptoms and the ones that did show it were thrown out? Crazy. Back in 2007 we were told that everything I was buying was free of HVX from two Dutch growers and 15 of 18 batches tested positive for some kind of virus (mostly HVX).

Then there are those suppliers who really do test for virus and it still can get through. Shady Oaks sent me a plant this spring that was loaded with HVX, and they were considered one of the best. Walters Gardens sent me HVX infected plants years ago too. At first they just blamed their original supplier of stock plants but then did warn people. The second time they simply said they weren't surprised but did absolutely nothing about it. They didn't even give me a credit! Walters is better now, and they virus index a lot of their perennials too, but if a perennial is not listed as being virus indexed in their catalog I think that just means that they found some virus and can't guarantee that you won't find it again.

So no, I don't take any stock in what the grower tells me. And there are so many other viruses out there other than HVX I think a negative HVX test gives a false sense of security. Like you, we learn who to trust, and even then we double check using test kits here and clean, clean, and clean some more.

Sorry for the rant, but I can get going some times...

Chris

[ViolaAnn]

Wish everyone could hear your rants. I keep harping about it, but you know, I'm been doing hostas for close to 15 years now, about 10 in a serious way. That makes me one of the old-timers. Us old-timers went through the peak of HVX around 2006-2008; so we watch for it. You don't hear so much anymore and some of the younger hosta growers who've just acquired the disease (hostaholicism) have truly never heard of these problems; so we need to stay on the soap box and preach to anyone who will listen.

[sweetee]

Exactly! I think Chris should rant more. I've also been into hosta for about 12 years now and am amazed at how many people like to just ignore HVX like it could never be in their garden.
I knew someone who only bought her hosta from chain box stores. When I told her about HVX she said; all of my hosta look healthy and everyone always tells me how healthy they look
Chris, rant away!