Yet another nematode discussion

[ThisIsMelissa]

I'm nearly paralyzed with anger.
Yes, I know... Nematodes a hosta garden are nearly inevitable. I'm ok with that. What I don't understand is why I am so much more upset by the nematodes that are showing up late in the season, as opposed to the slugs that show up early. Makes no sense.
What I'm not ok with is that of the now 23+ hosta in my garden with apparent nematode damage, all but 3 came from one private seller who is rather flippant about it and clearly is doing little to control them. I'm extremely upset at the notion that I have several dozen plants from this seller that I'm pretty much expecting will show up 'toded in the next couple years.

Anyway, I digress. (thanks for letting me rant)

It's August 31 here in MN and I feel like I NEED to do something, but I just don't know what's effective, practical, and cost effective. This is a second or third season for most of these plants. A few were added or moved this year.


I've done a search here and read nearly every thread about nems.
I've read about bleach treatment.
I've been told about heat treatment of the plant and boiling water for the hole.
I've read about Disulfoton in Bayer's Rose & Flower Care (2 in 1 Systemic), but that contains a fertilizer and it seems too late in the year to fertilize here. Please comment on this?
I've been told about acephate (orthene).

I've ordered a loupe, to confirm their presence, but at this point, I'm about 95% certain that this is what my garden is suffering from.

I'm really at a loss for what to do. Some of the plants are still relatively small. While others are a near mature clump size.

1. If I dig them up to treat them, should I wash off the roots in my driveway so as to not leave contaminated soil in the garden?
2. Should I replace the soil in the hole once the hole has had boiling water treatment?
3. My tap runs at 127º... would that be acceptable?
4. Is it a bad idea to put the plant back into the hole after it has had a heat treatment?
5. If they plants should not be placed back into their former home, what to do with them? pot them? I've never overwintered in pots. How do you do it?
6. I've heard you should put the infected plants in the sun for a year or two. Is this true?

Please... someone who has had reasonable success with the task of controlling these monsters, please tell me what has worked best for you?

Thanks so much!
Melissa

[Noreaster]

I'm no expert (far from it), but I did take mine out to the front yard to rinse off the soil, just in case. Though I figure the worms would all be within the plant tissue at this time in the season.

I've read every single nematode thread on multiple forums and am still at a loss myself.

Let us know if you see anything with the loupe. I couldn't, but am also virtually positive I have them in several hosta. They seem easy to identify, just by looking at internet articles about them. I tried the loupe last year and didn't do anything since I couldn't confirm the nematodes by sight. Wishful thinking, I guess. This year, those suspect ones started showing the signs again so I didn't bother with the loupe again. I also had them show up this year in one of my older hosta, which confuses me. I don't know how they got into that one, unless they've been there for the last few years and either didn't show symptoms (that freaks me out the most, because I figured you'd be safe planting a new hosta directly in the garden if you watched it thru the season and didn't see signs of nematodes come August), or I just missed them because I wasn't as informed a few years ago.

[DBoweMD]

About 4 years ago I divorced and moved my entire collection twice in 1.5 years, in pots dug from the ground, overwintering him. When I found nems I was able to immediately quarantine them.
I practiced using the heat (water bath) treatment and found it 100% effective, but very inconvenient and occasionally fatal to the plant.
I use the bayer (disulfoton) treatment about the past 3 years and find it best to pot the plant up and then treat it in the pot because you have an idea how much to put in. The fertilizer issue should not cause harm. I overwinter them in the pots, in a quarantined area of my yard.
I have put some in a few plants in the ground but have less confidence.
This method has been about 50% effective, meaning about half of the plants I treated last season got nematode damage, but it is less. If I feel like it, I plant the apparent cured ones in their pots in the ground and put some more bayer in this year even though they look OK.
This concentrates the medication/cure in the confined area of the pot. The plant must absorb this through the roots to stop the life cycle.
I was never able to kill the nematodes in the same summmer with the bayer.
I tried by putting my infected plants in pots in the middle of my ashpalt driveway all summer once I found them. in about 2007 or '08. After applying the granules I took samples at about 1 or 2 week intervals up to 2 months later and still found live nems every time under a microscope, wriggling around. (i'm a doctor)
Now that my plants are larger, I am considering dividing them and heat treating a part, and doing the chemical on the rest, so I don't kill the whole plant by accident.

[hostanquilts]

Another formula that I've tried is: 1/2 cup of hydrogen peroxide per gallon. I spray & staturate the plants with this mixture. Several of the plants that showed signs of the nems a couple years ago & I sprayed with this mixture several times during the year hasn't showed signs yet this year so I'm hoping that by starting in the spring & spraying every couple of weeks that I have eliminated the nems in these plants, but will keep and eye on them.
Good luck ... you might try several of these methods to get the best results.

[Chris_W]

Hi Melissa,

When you do the heat treatment of the plants your tap water should be fine, but it has to stay that temp the whole 10 minutes. I turned up my hot water heater a day before heat treating so that it was about 132 to 134 coming out of the tap and then once the hosta was in the water it was between 125 and 130 the whole time.

As for the dirt, you can shake it off out in the sun, or just heat treat it along with the rest of the plant but that makes it more important to get the water a little hotter.

After you heat treat the plnat you can pour boiling water in the planting hole and around the hole, fill with new dirt, but I would move the hosta to the side a little bit and not actually replant in the same exact spot. Nematodes can still live in the soil as the boiling water treatment isn't 100% effective on the dirt, especially if the infested plants have been there a while.

Some people have tried to just pour boiling water around the plants while in the ground, but again, there is a chance of killing the plants.

If it is a really large clump I would go with the systemic insecticides. You can buy Disolfuton without fertilizer in it, then there is Orthene with acephate, then there is the Bayer with Merit. Bayer also makes a 12 month tree and shrub formula. I tried it here on some Hibiscus and Iris and it didn't hurt the plants and lasted a lot longer.

The hydrogen peroxide won't hurt the hostas and Xerotol has been suggested for nematode treatments which is a concentrated and stabilized hydrogen peroxide so it should help a little too. Bleach has been suggested by a few people in the past, but there is no evidence (that I know of) to indicate bleach even kills nematodes let alone be able to get between the cells to kill them, plus bleach can damage plants as much as the heat treatment so I wouldn't even bother trying that.

Since it is really tough to completely eliminate nematodes from the soil you have to decide if it is reasonable to take all the effort to heat treat, pot or move them to a clean part of the garden, and then try to heat treat the soil. There is a chance that they will be back at some point, and with constant heat treating your hostas will be set back all the time. Since it sounds like quite a few plants in your collection have them I would lean towards using the insecticides. Think of it like treating for slugs and just remember to do it a few times a year.

I hope that helps a little!

Chris

[Pieter]

Bleach has been suggested by a few people in the past, but there is no evidence (that I know of) to indicate bleach even kills nematodes let alone be able to get between the cells to kill them, plus bleach can damage plants as much as the heat treatment so I wouldn't even bother trying that.

I used bleach on a batch of infected trades in 2007. All those trades were potted up upon arrival, so isolating them was already done and it made the treating of soil a non-issue, it was simply thrown in the garbage. Nems have not re-occurred and some of the plants have been further divided and are now planted in the yard. I used the bleach treatment as per a suggestion from Bruce Banyai. In a post on another forum he wrote the following at the time:

As someone who has watched the nematode hosta invasion for +35 years, I am reminded of several other notes after reading the excellent Kines summary.

Beware that your hosta are living organisms subject to environmental stress: they have natural defenses same as humans. When those defenses are suppressed or challenged the plants get weaker and opportunistic germs and Nematodes get aggressive. May be part of the seasonal explanation.

Most chemical treatments border on "killing the plant" and its pests, but if the plant has good genetic material, the pesticides kill the susceptible pests first: if the plant material is weak and dies as well, so be it.

My grandfather's Detroit area greenhouse/nursery business, started in the mid-1920's, used soil sterilization (steam) to kill soil-borne pests. They then began to use bleach when possible to limit further attacks on structures, pots and soils. This was in the era before chemical pesticides.

My mother, the late Pauline Banyai, the Michigan Hosta Lady, was often heard to say when she started dividing hosta: where is my bleach?

We would soak all new hosta divisions (before tissue culture, all commercial propagation was field grown, hand division) in a 5-10% bleach solution. Mom had traveled to various Midwestern USA nurseries/greenhouse operations during the 50' and 60's, seeing lots of nematode infestations in commercial field grown perennials beds. Her conclusion was these plants were then distributed around and thus we had non-native nematodes coming into the beds with plantings of these plants, before hosta.

Bleaching has minimized nematode problems for us - I still have much hosta stock from earlier days - and still "bleach" all my divisions. Last weekend I finished dividing 100+ clumps and had seven 18-20 gallon blue plastic tubs with bleach solution in operation! remember to keep these in the shade and use cold water - hot water bleach will kill hosta divisions quickly! If it is mushy, it is dead!

If I get a "keeper" hosta that I need to rid of nematodes, I will divide it down to singles, cut out all woody tissue and leave in bleach solution overnight. Set it aside with notes that it was infected and watch it for a couple of years - repeat if necessary.

I have thrown out more plants recently (not worth the effort for big yard with many plants). I also used Terrachlor (no longer available I think, if you can get some old stock use it!) and sprinkled in the soil after digging the plants. More chlorine-based poison!

Hope this helps - nematodes can be managed when some sanitation and proper watering.
Bruce

Bruce goes on to say:

I should add that dirty clay encrusted divisions need to be bounced hard and broken up, to remove the dirt. Any organic material in the soil or inorganic clay/sandy soil will take up the bleach and you will have dirty water! If I can't smell bleach or see the divisions, change to new bleach solution.

Leave them soak a couple of hours, depending on size. Smaller divisions less, thicker heavier divisions longer.

Yes, I have sprayed 10% bleach around infected soil, but for the above noted reasons ( I am a chemical engineer by degree, working in soil microbes now) the effect is negated, unless you use huge amounts for longer lasting treatment.

Why I don't bother with ZeroTrol - too expensive and not long enough lasting in the environment for what is claimed.

Yes, diluted bleach is an old remedy to kill germs and microbial pests. Chlorine is short-lived but nasty to these life forms. Larger and more concentrated amounts are nasty for humans as well.

[Chris_W]

Hi Pieter,

If I read it correctly then Bruce is saying that bleach isn't 100% effective. Anecdotal stories like this sound interesting, but I haven't seen anyone with empirical evidence that bleach kills nematodes within hosta tissue. While I will concede it is a good surface cleaner for germs and fungus I would think that if it can get into the cells of a hosta then it would kill the plant.

Thanks for sharing Bruce's story though.

Chris

[Noreaster]

I thought there weren't any insecticides available to home gardeners that were effective? Are the ones mentioned only partly effective?

[Chris_W]

Hi,

The insecticides mentioned are only partly effective, but enough to prevent the damage when sprayed a few times a years. There isn't anything out there that is 100% effective at getting rid of nematodes in the garden (or even commercially) which makes it important to quarantine new arrivals, especially if you don't already have them. But the insecticides mentioned will hold them back quite a bit in your garden.

[Noreaster]

And how long should you quarantine? One of the ones I planted last Spring looked fine last year but has a few suspicious spots this year. Can it take a few seasons for damage to show up if the plant has worms?

[ThisIsMelissa]

And how long should you quarantine? One of the ones I planted last Spring looked fine last year but has a few suspicious spots this year. Can it take a few seasons for damage to show up if the plant has worms?

I can tell you that some of my plants were purchased in 2007 and 2008 and are just now showing evidence.
By contrast, some purchased this year and last year showed evidence the year of their purchase.

[Noreaster]

Ugh, see, it seems as bad as HVX then. Maybe even worse, because I feel like I can be reasonably certain not to spread HVX from one plant to another, even if a hosta doesn't show signs. But worms traveling thru water? How am I supposed to ensure that doesn't happen? I've got a small garden...can't leave a 6 foot radius around each hosta and I don't have room in my garden to effectively quarantine groups of plants. Or even keep the quarantined plants sufficiently spaced away from the other quarantined plants!

[ThisIsMelissa]

Ugh, see, it seems as bad as HVX then. Maybe even worse, because I feel like I can be reasonably certain not to spread HVX from one plant to another, even if a hosta doesn't show signs. But worms traveling thru water? How am I supposed to ensure that doesn't happen? I've got a small garden...can't leave a 6 foot radius around each hosta and I don't have room in my garden to effectively quarantine groups of plants. Or even keep the quarantined plants sufficiently spaced away from the other quarantined plants!

Ditto on HVX vs nems.
And ditto on no room to quarantine.

This is why I'm so frustrated.
No techniques/products to eradicate.

Slugs I feel I can deal with, if diligent enough. Nems, I feel somewhat powerless.

[Noreaster]

I agree, it's very frustrating not to have a clear cut solution as far as getting rid of the ones you have and preventing bringing any in. It seems like a safe thing to do is heat treat all new plants (not just hosta) as it comes in. Completely impractical, of course, unless one is starting a brand new garden with nothing in it but virgin soil and a have lot of free time to boot. Which is why I'm leaning towards just living with any new ones that may pop up. Though I'm far from at peace with that solution. It's just that all the other solutions basically seem futile. I will be trying the peroxide thing next year, though, if I have any more suspects.

[ViolaAnn]

Ditto on the frustration expressed above. I have a couple of plants showing signs. The pesticides, I'm quite sure, won't be available for me to purchase in Ontario. That leaves heat treatment, bleach or hydrogen peroxide. Or ditching the plants. This year it's two plants near each other - (not so) Fair Maiden (which of the four years I've had it, did well in my garden only the second year) and Silver Threads and Golden Needles (of which I was sent a second plant as a bonus).

Ann

PS - This whole discussion shows the value of taking regular pictures of the collection. I first noticed it while editing pictures rather than by looking at the garden.

Fair Maiden

Silver Threads and Golden Needles

[ontariohostaholic]

It seems that nematodes are showing up more and more with the change in our climate ....as well as higher UV levels and dryer summers. Could we be getting more nematode infestations because we are depending more and more on compost and mulches that may or may not have been heated up enough to get rid of nematodes / parasites etc. ? We are all so eager to conserve moisture by using mulches made available from our garden centres and/or free from our municipalities. You can quarantine your hostas for a year or two but there really is no 100% guarantee that you've crossed that "no nematodes / no disease" barrier. Let's all do our best by doing what we can to prevent increased populations of nematodes and ensure that we are careful when we share divisions from our gardens. I think most gardeners will realize, with time, that they have nematodes to some degree and that by using good gardening practices (and at least attempting some form of combat) they can keep nematode populations / infestations down.

[Noreaster]

Found this little volunteer seedling yesterday with a suspicious streak. The parent plant is either Tokudama F or Blue Cadet, neither of which show any signs of nematodes and are several years old, in the ground. My question is, is there anything OTHER than nematodes that damages the tissue between the veins like this?

[John Polka]

Well unlike HVX... we can do something to decrease the activity of the nematodes... and unlike HVX the nematode is its own living organism...where the HVX is disease... unlike slugs we cannot see them...BUT just like slugs... we'll never completely rid ourselves of them....they're worms... its sad that we can trade/sell our hostas and never truly know if we are sending nematodes with them... but thats just part of it....
So I just say quit freakin out lol...This is my first year as a hosta collector... second year for growing... I've picked up and learned the cultivation and culture quickly thanks to many on the Garden Web forum... this is actually my first post here on Hallson Gardens Forum... I'm gonna steal the words out of Ken's mouth... If you are losing sleep over nematodes...maybe you should grow daylilies instead....
I agree so much with what Chris said in his first response to this thread... use an insecticide... I use Bayer 12 month for Trees and Shrubs.. just lightly...for nematodes... spread Worry Free Slug Bait for slugs... spray with Bayer Disease control every couple of weeks for anthracnose and rust....plant them right...water them right...
And call it done... whatever happens... happens...
Personally I think anybody that says they trade or sell 100 percent nematode or HVX free is a big liar... expect to get a plant everynow and then with both if you plan on buying lots of Hostas... its just my opinion... we can all do what we can to decrease the spread... but ..it.. happens...not saying most people or anybody in particular would do this purposely... but it happens....This is our culture...hosta culture... and I love it =P
Thanks
John

[ViolaAnn]

In general, I agree with you. BUT, you wrote

I agree so much with what Chris said in his first response to this thread... use an insecticide... I use Bayer 12 month for Trees and Shrubs.. just lightly...for nematodes...

That's fine if you can buy such insecticides where you live. In the Province of Ontario, we cannot.

[Noreaster]

I'm actually trying not to freak out about them because they seem to be everywhere. I've finally realized that those black splotches on my Jack Frost Brunnera are nematodes and according to some things I've read online, that's incredibly common in Brunnera. It's just when you go online and read various sites telling you that the only proper course of treatment is to dig up and throw away the plant and any plant within a 6 foot radius (or heat treat said plants), it's hard not to get kind of down about that. Now, I have no intention of tossing away any of my plants unless they have HVX. I don't really feel like I want to use an insecticide unless it is going to get rid of the nematodes, which it won't. It just controls them somewhat, maybe. If I were to get an infested hosta in a trade I would not hold it against the person that sent it to me. At the same time, the idea of me sending one with potential nematodes in it DOES bother me, I can't help it. It's annoying to know that they are in there, and I don't want to pass that headache on to anyone, so I will probably not trade plants.