Foliar Nematodes have become a problem in my garden in the past couple of years. 2 years ago they were suspected but not confirmed. Last year I bought myself a jeweler's loupe and confirmed their presence in several plants which I removed and poured boiling water into the area around where they plant had been. I've already seen their symptoms in several plants this season including the first one that I would consider valuable.
In the province of Ontario we have a pesticide ban and cannot use or buy the most potent chemicals. From what I've read, they are extremely common in the garden and in other perennials as well. We can treat or destroy a plant and we can pour boiling water into the soil around where it was, but seems to me once they are in the soil there is little we can do.
Are they, perhaps, something we will simply have to learn to live with and accept as part of the late season cycle of hostas?
Here's 'Ghost Spirit' about 10 days ago when it looked good. Today several leaves showed clear evidence of the beasts.
I see no nemes this year in the 4 or 5 hosta I heat treated last year. The one I left untreated in a corner has nematodes again, so I would say that water bath does work, even though I doubt I'll bother with it again- I do believe they are inevitable. I have them on brunnera (as I think almost everyone does), heuchera, and I would suspect ferns as well.
Ann I am paranoid that they could be in my one Pandora's Box last year so I dug it up and potted it up and are waiting to see what happens this year. It is far away from my other plants and I'm taking great care with how I touch it. It seemed to be fine in the spring and as the season goes it changes and from others talk about it I "think" it may have a problem but I'm not sure.
It came from a good greenhouse here in Edmonton a few years ago.
I asked the same question over on the Hallson list and this was Chris's reply -
Quoting:The heat treatment can work to eliminate nematodes from an individual plant, but then when you put it back in the garden it will be smaller (if it survives) and will catch them again anyway if they are all over in the soil. You can also heat treat the soil by drenching it with boiling water though that is not 100% effective but only about 80 to 90%, depending on which study you look at.
Unfortunately I think nematodes are going to be inevitable. I see it at so many nurseries and in so many gardens already that they aren't going away any time soon, especially with all the trading that happens, and all the backyard hosta sales that I see all over the place. The only way to get rid of them would be to start over in virgin soil that has never seen a single ornamental hit the dirt and then start with absolutely clean, new stock that has been quarantined long enough to make sure that they are nematode free, and likely you would need to test them to make sure they didn't have nematodes before planting. In other words, it may be darn near impossible :(
Too bad. But I vote to keep my plants nems or not. They will still look good for half the season.
As noreaster said, they affect heuchera and brunnera as well. I've seen the effects in my brunnera and might ditch it. But I've seen them in more than one area of my garden as well. I only hope I didn't spread it to a lot of other people when I did my hosta sale last spring. I guess no more hosta sales from my garden.
Most of mine looks less than perfect this time of year, anyway. Since they don't seem to affect the plant's vitality, I'm just going to live with them too. It makes for too much work to try to keep everything absolutely sterile. Slug management for the first three months of the season is all I can manage.. Bugs happen, I guess.
I noticed a product called ZeroTol and it is 27% peroxide and that is not a pesticide. So, what might happen if you just mix some peroxide and water together, one part peroxide and 2 parts water. This kind of fungicide is considered safe so why no give it a shot.
He doesn't really deal with practical solutions. If you cook the plant, the likelihood is that the plant, if it survives, will be stunted. And if you have many plants infected, it's way too many too cook. And they will likely get reinfected when you replant them as getting rid of the nems in the soil may be impossible.
I've cut off all plants showing any signs of them as soon as I saw them in the plant and they did NOT go into my compost, bur rather city yard waste. I'm also starting to cut down ALL of my hostas (sterilizing my cutters well between plants). I will concentrate on a very good clean-up this fall. I will also soak each plant with a Hydrogen Peroxide solution (I think it's about 1 cup per gallon of water, but will have to check that). And in the spring, I will dowse the soil with hot water as much as possible.
My research in the past on nems seemed to indicate that the infestation is caused by a decrease in the soil bacteria/microbs which keep this parasite in check. I understand that the parasite is opportunistic in that conditions have to be right for the parasite to move in. I believe I have one infected hosta (Peppermint Ice) which I bought from MIG. I am going to spread corn meal around the plant soon to encourage the increase of the beneficial microbs. Once the leaves dry out, I plan to remove the leaves. I have been careful not to transmit the nems to other plants by means of tools, watering etc. I think that to halt a spread of this parasite it helps to increase the beneficial microbes in one's soil and to leave some space between hostas.
I think I mentioned this somewhere already, but the ones I "cooked" last year are all neme free this year and not significantly smaller. Now, I have an older hosta, Manhattan, which is showing signs for unknown reasons and I have no intention of doing anything about it...maybe 'll try cornmeal next year if I remember. No way am I digging it and cooking it at the size it is now. I bought that one from a hosta grower that I think sells tissue culture ones, and none of the others from that vendor show signs of nemes. I did make two new purchases this year from mail order and a local place, and both new ones look suspect. I'll probably just leave them be and revaluate next year.
ViolaAnn, all the hostas I got from you show no signs of nems. They're all doing great. At the moment I'm top dressing the hostas with mushroom compost as I was advised to do by visiting hortuculturist at Loblaws last summer. She said that the frost and earthworms would incorporate it into the soil. The GardenWeb in their grass section recommends cornmeal to augment the beneficial microbes in the soil and topdressing the grass. If this keeps grass healthy, I don't think one can go wrong by increasing the beneficial microbes around one's hostas. I wonder what the ammonia wash does to other critters besides slugs in the spring.