Hallson Gardens

I'm thinking about buying a small pack of test strips to test a handful of hosta in my garden that I think of as high risk because of the cultivar and/or where they were purchased. They don't look symptomatic at this time, but I know about the potential long dormancy of the virus. I guess I'd rather know now, rather than sit around waiting for it to show up...I've already had HVX rear it's ugly head in plants that were in the garden for a few seasons before displaying the signs. Question: If the virus is still dormant, can I be assured that the test results will be accurate if I do them now?

It is possible to get a negative result and still be positive for the virus. If the plant is infected, but not above a certain threshold then it may not trigger a positive result. I would likely wait until I saw symptoms or really suspected something was not right before using test strip on it.

Mike

On the other hand, the test can usually show a (proper) positive result before the leaf shows symptoms; Agdia says their threshold is low for detection. No symptoms doesn't mean the virus is dormant—as far as I know, HVX doesn't have a true dormant state, it's just a matter of building up sufficient concentration to affect the plant, which can vary from plant to plant. If you test the plants now, and the results are negative, then you've bought some peace of mind if not absolute certainty. Then, if you're still concerned, test them again next year.

David

I just bought some of the test strips from Agdia. Tigger explained it the way I understand it, too, from Agdia's literature. If I read it correctly, the strips will show a positive even if the virus is in pretty low concentration.

I had 2 hostas test positive that I thought I saw symptoms on. The results showed in just about 2 minutes. One was a Birchwood Parky's Gold that this is it's 4th season here. I always thought they showed pretty early....so I may not have been as careful with it last year as I should have been...

Thanks, everyone. I'm still mulling it over, but am leaning toward buying a five pack of the strips. I have two four year old Parhelions I want to test because I feel they sunburn really easily even without a lot of sun, and had read that could be a potential symptom. Plus I heard it can take up to seven years for those to show the HVX signs, and I'd really rather not have to dig up a seven year old Parhelion. And one other one I wanted to test because I have it nestled in with a group of hosta that I consider to have come from a safe source. That one I picked up at a local nursery, and I've seen HVX in just about all the local nurseries and garden centers, so I'm leery. (I bought it in a moment of weakness)

I would go for it then. I don't know what the threshold limit is to trigger a positive response. David is right, if you test them now and they are negative you've at least bought some time. I think the strips/solution likely have a shelf life of a year. If you buy 1 set of 5 now you could test this summer and then again next spring without having to buy anymore. $6 for some peace of mind isn't a bad deal.......

Could I ask where you found the strips available in the 5-pack? From Agdia, the smallest pack I found was 25...

I've seen them at Adgia in 5 packs. I think the default setting is 25 strips. Try to change it to 5.

eastwood2007 wrote:
I had 2 hostas test positive that I thought I saw symptoms on. The results showed in just about 2 minutes. One was a Birchwood Parky's Gold that this is it's 4th season here. I always thought they showed pretty early....so I may not have been as careful with it last year as I should have been...

Ugh, that is a bummer. That's what I hate most about this virus..you wait years for these things to grow up and look great, then it shows up and ruins everything. I was also wondering if there was an "average" amount of time before the virus shows symptoms...of the two cases I had, both were entering their third season in the garden when I noticed them, in the Spring...and both hosta were decent sized when I bought them from local nurseries. But I know someone on Daves Garden had a seven year old Parhelion that had it, which is why I can't breathe easy about mine!

Hi,

In the testing we've had done there have been negative tests by ELISA testing in the first season of Dutch plants that at the same time tested positive by electron microscopy. Those plants would have also tested negative by the test strips, since the strips are 99% as responsive as ELISA. For that reason we always wait until the end of the first full growing season before testing any asymptomatic plants, but still, that has missed a few in the past, so I repeat the following spring if I'm suspicious of the source.

Regarding a Parhelion taking 7 years to show symptoms, I would wager that this particular plant was either infected much more recently in the garden or symptoms just weren't noticed right away. First, there aren't any known wholesale cases of Parhelion being infected, secondly, the virus usually shows up much more quickly in yellow tissue, and lastly, if the plant was infected at planting time, there were probably visible symptoms much earlier than 7 years that simply went unnoticed. Early virus symptoms can be very subtle, but if you know what you are looking for, and are actively searching, they can be found. Often it just takes the untrained eye longer to notice it

Overall I'm happy with the test strips. They are slightly cheaper than laboratory testing and easy to use, and yes, they work very quickly if HVX is there.

In my opinion, if you had a hosta in the garden for at least 1 or 2 full seasons, and assuming it was infected when it was sold to you, there is a good chance the strips will pick it up. First season plants may or may not test positive if the virus is there, but so far I haven't seen false negatives by ELISA after that first year.

Noreaster wrote:I have two four year old Parhelions I want to test because I feel they sunburn really easily even without a lot of sun, and had read that could be a potential symptom.

Hi again,

I wouldn't judge "sunburn" a symptom. What we have seen before is that the virused tissue, ie collapsed or discolored parts of the leaves might get sunburn or sun bleaching. However it isn't completely agreed that this was caused by sunlight.

Remember, holes or browning in the leaves is not a sign of any kind of virus. If your Parhelion is burning late in the year from sunlight it is probably from too much heat (is it against the house or a building?) or not enough water.

Hope that helps a little.

Chris

Thanks, Chris. Lots of good info there...I have two Parhelions that are both displaying signs of sunburn now, so very early in the season. One is against the house (north side) and I had just moved it there shortly after it broke ground this year...and it's possible I hadn't watered it well enough after the move. I find the ones with the huge leaves hard to water in general. Although we are still quite cool here, there was a period of a few super hot and windy days, so I was hoping that had contributed to that one's poor condition. But the other one is in a lot of shade and extremely protected, so I am surprised to see "burn" on those leaves. But, you've eased my mind a bit about them at any rate so I'll try to stop worrying. I really don't see any of the collapsed tissue that my other HVX infected ones had, or the ink bleed along the veins.

are you thinking of my parehelion? This is the post, from 2005: viewtopic.php?f=63&t=35350

If you read it, Chris thought that my 7 yro S&S was the "carrier" even though parhelion showed the symptoms first (a whole year first). And I can assure you that for 7 years there was not not a sign, not a single mark on that S&S. I walk my gardens daily and look at all the plants. (Especially since then) And for the 3 years I had parhelion it looked fine too.

My conclusion is that Chris was right and the S&S was the carrier and took 7 years to show anything, and even then it was only a couple of leaves/eyes and not every part of the plant.

OR the parheilion even though tc'd must have gotten it from the nursery that got the tc's in... but I have never seen a hosta there that had any symptoms and I go there every year. Thats actually one of the reasons I continue to go there

And as an update: Even though it's only been 4 years since, I have not had hvx show on any other hosta. And I do look at them almost every day, and look at every mark. (I'm paranoid now, ) So, unless it is taking it's time "showing up" again, those were the only two culprits (and I managed to get rid of them monsters withoug spreading it! , though they were the only 2 planted in the front of my house.)

Hm, so is there any kind of average length of time that you guys have found that you have a hosta show signs of HVX from the time you brought it home?

I just looked at the protected, unmoved Parhelion, and it really looks bad this year...I guess maybe it could have been damaged from the colder parts of Spring, even though I did keep it covered on the coldest nights once it broke ground. And to add insult to injury, there is a fist size chunk that was eaten be some kind of caterpillar/worm on one of the top leaves. I'm kind of glad it's in the background, because up close, it's not pretty this year.

Is there a picture somewhere of what a positive test result looks like? I had just one strip left from last year (I was given a few by a friend). It MAY, of course, be too old, but it's been in the fridge all year. But I can't seem to find any instructions which I must once have had. I've got one hosta looking a bit suspicious.

Ann

Here is a link to a pdf with the instructions on how to use the strips....

https://orders.agdia.com/Documents/m273.pdf

Thank you. I'll save that and file it where I (hopefully) can find it next time.