How do you handle Nematodes?

Steve Massachusetts Zone 5bAugust 17, 2012

Do you:

1. Ignore them

2. Pull of the leaves

3. Dig up and throw out the plants

4. Bleach them

5. Do the hot water bath

6. Put them in a hot car

7. Go all Sadam Husein, and declare chemical warfare

8. Bring them to the Hosta Society raffle

9. Other tactics.

I just dug up and threw out 20 plants and poured 4 gallons of boiling water down each hole. That took me a while.


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Wow Steve, that's impressive. I have no energy this time of year to do anything about them. Two years ago I dug up and heat treated five hosta, and saw that one of those this year has nemes again. So I probably will no longer do the heat treatment. Either i just supressed them a bit, or that one hosta somehow became re-infested, I don't know.

I have many more showing obvious signs of nemes this year. All are ones that have been in the garden for several years and I have not noticed them in the plants before. That has been a real bummer. They are spread all over the garden, so it's not like they caught them from a neighboring hosta.

It sucks, but since there does not seem to be a chemical treatment available to the home gardener that is proven to work, I choose to just ignore them...I will remove all the leaves after the first frost, however. I don't usually clean up the garden til Spring.

I see no point in trashing the ones that have them because who is to say that the plants I replace them with won't do the same thing- i.e. live there happily for a few years and then bam- nematodes show up. I want a garden of plants, not a sculpture garden. I feel that they are basically unavoidable. It just makes me mad that the powers that be can't put something out there that home gardeners can use. Doesn't seem like it should be that hard to get rid of a worm.

    Bookmark   August 17, 2012 at 5:18PM
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ken_adrian Adrian MI cold Z5

ignore them


    Bookmark   August 17, 2012 at 5:22PM
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bernd ny zone5

Steve, how do you know which plants have it, you probably missed some which do not show any damage yet this year. I see them popping up on a single leaf, one small area between veins at a time, on leaves growing under an upper leaf. I read somewhere that such nematodes will continue to live in the soil. They simply pop up middle July through August here.

Somewhere I read we should not do overhead watering of hostas. I thought about that advice during a recent downpour, was outside under my umbrella observing my dry creek now carrying a little stream. And then I saw how the big rain drops were hitting large hosta leaves and then dispersing into all directions as small droplets. So how do you avoid that, planting with a lot of empty space around hostas? That single downpour possibly dispersed nematodes everywhere.

So I decided to live with them. I do not throw out hostas any longer for that. Only HVX ones get thrown out, carefully. I noticed spraying Bayer Advanced Complete Insect Killer every 2 weeks starting midJuly keeps them at bay. One H.'Cathedral Windows' had a lot bad leaves last year, none this year, yet.

One member of my hosta society mentioned last year that all hostas are no longer perfect in August, some leaf damage goes with the season. Much worse off than the hostas having a little nematode damage now in my garden are the ones having severe damage from too much sun. From that perhaps we should start to discuss not to plant into too much sun.

I rip out nem-damaged leaves, rip out spent scapes with my hands, do not cut them, except when bathing the tool in bleach after each plant.


    Bookmark   August 17, 2012 at 5:31PM
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"ignore them" - ken


For the gardener, it seems to me like a dog chasing it's tail...very engaging and enthusiastic in effort but unlikely to catch... and the tail will still be there after the chase.


    Bookmark   August 17, 2012 at 5:56PM
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pinch off the affected leaves and hope for less return next year.

    Bookmark   August 17, 2012 at 7:34PM
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Steve Massachusetts Zone 5b

I did get one plant from the Hosta Society raffle with nems. Luckily I had kept it in a pot and on a cement patio, so I could just chuck it when the brown stripe appeared.


    Bookmark   August 17, 2012 at 7:49PM
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It sure makes me glad I have mostly container hosta.

After I had the first three plants contract foliar nematodes and bleach soaked them, threw out the potting soil, cut them back to basics, and isolated them, they are now growing very nicely thank you. Two are my #2 and #3 plantaginea, and a Lakeside Kaleidoscope, the latter not as vigorous as the plantaginea. Those are growing like crazy with all the rain, and I even put them in more sun because I figured nothing to lose by doing so.

I'm a bit suspicious of other leaves now and then, but I figure I'm likely to have shriveled leaves and insect damage, but the hosta appear vigorous enough to live a normal life anyway. I'm not creating a display garden, as mentioned above. I think I'll do what Melissa suggests, pinch off or snatch and toss the bad leaves. What is left doesn't look half bad now, and I'll also hope for the best next year.

    Bookmark   August 17, 2012 at 11:36PM
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ilovetogrow z9 Jax Florida

Put them on Ken's driveway. Do you have a photo as I am not sure what it looks like. Not Ken's driveway but the affected plant. Thank you Paula

    Bookmark   August 18, 2012 at 12:08AM
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This seems to be a recurring topic, and rightly so, since it's, as Doug Beilstein (aw heck, I think I don't know the proper spelling of the AHS President, oops) once told me, it's not if but when you will face this.

The only known, by me, long term solution, is a 'systemic nemacide'.

Good luck finding a way to git this. I've, probably, hundreds of hours of internet searching, to no avail.

Now it seems that if I could and would be willing to approach some friend in another country to buy and ship me, surreptitiously, some of it I'd be a happy camper.

Someone, somewhere, fairly recently, decided that only 'registered' applicators can buy this type of product.

As a person who cares about rampant chemical problems in our world, I think I understand the concern with 'systemic' chems, since there are all sorts of concerns in this regard in our food chain.

However, since, in this country (U.S.A., in my case), Hosta are not considered a food plant, I plead the U.S.D.A. et. al. to let us have this systemic nemacide.

Pretty Please,


    Bookmark   August 18, 2012 at 12:30AM
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Steve Massachusetts Zone 5b


The first picture is a clear shot of nematodes. They usually don't show up here in the north until July and August. In FL a lot earlier.

I forget which Hosta that was. Maybe Spring Fling. The brown vein is there because the microscopic worms can't eat their way through the vein walls. Hosta's have parrallel veins so that's why you see this pattern. It looks different in plants that have palmate veins, like Heuchera.

Here's a pic of Satisfaction with nems.

The leaf on the left has just the beginning of a vein with necrotic tissue. The one of the right is more advanced. This plant was uphill of several others to which nematodes spread. They spread through rainwater or overhead watering. My plants are young and do not have leaves that are touching. Thus the spreading was determined by gravity directing rainwater.


    Bookmark   August 18, 2012 at 6:56AM
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bernd ny zone5

HH wrote "approach some friend in another country to buy and ship me,"

Ah, I forgot that, there was that foliar nematode killer in Europe. So I should find the name, then talk to my brother over there....? What's the name?

    Bookmark   August 18, 2012 at 6:59AM
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andy10917(NY 6a)

Like others, I've spent a lot of hours looking for an effective and legal treatment for nematodes. What I DON'T find is anybody's results saying "I tried this claimed treatment and it's bunk". The specific product I'd like to hear anybody's experience with is "Azaguard", which makes claims about being an effective treatment for foliar nematodes in Hosta. OMRI and all that. Has anyone tried it and said "junk"? All I can find is more of the manufacturer's claims - no forum discussions pro or con.

    Bookmark   August 18, 2012 at 10:09AM
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ilovetogrow z9 Jax Florida

Thanks Steve. I was not sure what to look for. I do grow in pots but I think I have this on my Night Before Christmas as the white did not appear but went brown. I am stuck in LA, California for another week going through hosta withdrawl big time so I will take a closer look when I get back. Paula

    Bookmark   August 18, 2012 at 10:27AM
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Steve Massachusetts Zone 5b


I've seen that advertised also, but have not used it. I'm skeptical since the website doesn't give any information about why it's effective or how to use it. If nems are on the outside of the plant during their Spring migration or during times of high humidity, then they are quite vulnerable and can be killed with insecticidal soap. But since they live inside the leaves and the crown and in the soil, I believe it's going to take a better understanding of the migration period in order to control them.

Here's an interesting recommendation from the University of Illinois.
" The use of a dry surface mulch or a ring of petroleum jelly around the base of stems helps prevent the nematodes from migrating up the plant stems."

That's worth trying.


Here is a link that might be useful: Foliar Nematode Disease of Ornamentals

    Bookmark   August 18, 2012 at 11:39AM
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Just did a quick tour of the garden and it looks like four out of the five hosta I heat treated two years ago look like they have nemes again. That sucks.

    Bookmark   August 18, 2012 at 12:02PM
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bkay2000(8a TX)

Since I grow in pots, I didn't think I would ever have a problem. I was wrong. I found them on my Wide Brim and tossed it, pot and all. I'm not sure how I got them. I had put those WB's in a planter box for a season. So either the hosta came with them or that planter box is infected. It has had all kinds of tropical ivies and annuals in it previously. I also bought the WB from two different sources, so there's no way to know how I got them.

According to the Georgia extension service, "Some of the more common hosts include strawberry, hosta, fern, begonia, chrysanthemum, dahlia, phlox, verbena, zinnia, carnation, ficus, gloxinia, impatiens, lily, and African violet." They also say, " If individual plants are of sufficient value (such as breeding stock or rare ornamentals), then a combination of nematicides and hot water dips can be used to try to rid the plant of infection. It must be noted that these methods are only partially successful and some plants will never be rid of the nematodes." Note that they say, "try to rid".

I think I'll stick to pots.


    Bookmark   August 18, 2012 at 1:46PM
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If the white section didn't appear on the entire plant, I'd say it's more likely meltout, rather than nems.

With a bad case of nems, they still would have eaten and left stripes on the green sections too.

Post a pic?!

    Bookmark   August 19, 2012 at 9:01AM
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ilovetogrow z9 Jax Florida

thisismelissa here is the best one I could find. As stated I am in California not home. Thank you Paula

    Bookmark   August 19, 2012 at 12:27PM
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Paula, I'm not sure you have nematodes based on what I see in this photo. My plants had a darker brown searing and not the bleached dead skin look.

Here is the picture of my plantaginea with foliar nems, and it was very early this spring when it happened. With you at the same latitude and about the same climate, you'd have experienced it earlier than other locales too....or so I assume. The darker rustier brown is the nematode sign. I also treated those with the bleach soak, threw away the soil, bleached and dried the pot and have not used it again so far. Sort of leery of taking chances on it again.

And, here is the photo of the two plantaginea that had the nems, taken this week. So far so good. But they will remain in containers you betcha.

    Bookmark   August 19, 2012 at 1:55PM
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ilovetogrow z9 Jax Florida

Moccasin I am going to have to take a close took when I get back. That plant has had the brown markings most of the summer but has continued to be ok otherwise. I had been looking forward to the white showing up someday. There are no Hostas in the Los Angeles area. I am sure of that. Have a great grow day, Paula

    Bookmark   August 19, 2012 at 5:14PM
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When most other shade tolerant plants carry foliar nematodes like heuchera, asilbe, ajuga, anemone, daylily, impatiens, peony, vinca, and other species. So getting them introduced to your garden is pretty much inevitable. Unfortunatly it will be something we will have to tolerate for now. The destroying plants and the boiling water drench will only make you feel better for a while....till you see them next year or the year after that. They used to say the northern gardens were safe but they have been shown to survive -80 temps.

Black Hawk Giboshi

    Bookmark   August 19, 2012 at 7:42PM
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I have taken the same radical tact as you have Steve. Dug up infected hosta. Bagged them and threw them out. Then treated the holes with boiling water. I destroyed quite a few nice specimens. The good new - I have not seen nems in three years.

I also heat treated a few plants - two are in their third year in pots - no nems yet - however very slow to grow. I would not advice this as it is too much work and little reward. I should have just bought new plants.

I also buy buckets of crab shells and mix them with the soil each time I move or add a new plant. Supposedly the crab shells create a bacteria in the soil that will attack nematode eggs. Are the nematodes they describe the same as the foliar nematodes in hosta? Who knows. However the crab shells add minerals to the soil too.

I don't do swaps with strangers (that is one of the ways I introduced Nems to my garden). I also don't buy from hosta vendors that don't care about these things. Trust me, there are quite a few. I have vendors I trust and only do business with them. And don't buy hosta in the local garden centers. I was shocked when I visited one of my favorite garden centers in August, only to see all the beautiful hosta with nems.

Here is a link that might be useful: Crab Shells

    Bookmark   August 20, 2012 at 9:36PM
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Pieter zone 7/8 B.C.

Then treated the holes with boiling water. I destroyed quite a few nice specimens. The good new - I have not seen nems in three years.

Wish my experience was the same.... I had a 'Maui Buttercups' last year that showed nems, so it was dug up and tossed since I still had another specimen and the hole was filled with boiling water. I thought that'd be the end of it. Now this year in a spot near to it I have my lone 'Hanky Panky' and it now shows nems. This one will be dug up, bleach treated, the hole will get dug deeper and larger and the soil will be disposed of, get the boiling water treatment and be refilled with fresh soil. I've been successful with the bleach bath before, so I keep my fingers crossed it'll work again.


    Bookmark   August 21, 2012 at 10:36AM
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