Know Your Nems - Answer thread

Steve Massachusetts Zone 5bOctober 7, 2013

Go to the Quiz thread first if you want to take it. The answers are below.

Here you go.

Number 1 - Yes
This should be an obvious one. Notice how the damage starts in the petiole and continues into the leaf. The giveaway, however, is that one vein that continues up into the leaf. Notice that the dead tissue is delimited by the veins.

Number 2 - No
This is typical tissue damage of a Hosta getting ready for dormancy. The necrotic or chlorotic tissue is not vein delimited.

Number 3 - Yes
This one is really subtle and would be easy to miss, but the key is that the damage is limited by the veins.

Number 4 - Yes
A little more subtle than #1 but from the same plant. The tissue damage on the margins of the leaf are probably not nem damage. However, the brown streak up the petiole continuing into the leaf veins at the "throat" of the leaf is a characteristic sign.

Number 5 - No
Sun damage or just getting ready for dormancy. The tissue damage on that vein on the bottom is not limited by the veins. Nems will eat through the entire section between the veins.

Number 6 - No
The necrotic tissue is not vein delimited.

Number 7 - No
Once again the damage is not vein delimited.

Number 8 - No
That light green streak in the plant is just part of its streaking. The necrotic tissue is not vein delimited.

Number 9 - No
I'm not sure what this is but I'm pretty sure it's not nem damage. The brown area goes up the throat of the leaf, but it's rough on the surface and doesn't seem to spread.

Number 10 - Yes
OK, I cheated this is a Brunnera. Nems do not only appear in Hostas. They are in many many different plants including weeds. However, they appear differently in plants like Brunnera which has palmate veins and not parallel veins. The tissue damage is still vein delimited in Brunnera, but looks different because of the different vein pattern.

So how'd you do.

100% - You're a Nematode Ninja, stalking your garden with a shovel and a bottle of Zero-tol, while the water boils on the stove.

80% or above - You know what you are looking at, but you may not care if your plants have nems, or you've resigned yourself to living with them.

Below 80% - You need to go shopping for Hosta at a local nursery in August or September in the North (earlier in the South).

Don't worry I was in the garden of a fellow Master Gardener a few weeks ago and she had no idea what nematode damage looks like.

It's a nematode world, we're just living in it.


This post was edited by steve_mass on Mon, Oct 7, 13 at 13:41

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josephines123 z5 ON Canada

Steve, this is an excellent teachable!

What a great exercise for yet another rainy day...I'm only sorry I didn't participate online...playing Gramma today and I had to make play dough pizza...priorities you lol lol.

I see that I would have had 2wrong...but I recognized the brunnera, yay....what a great thread,Teacher Steve.:) Many thanks for such valuable information and for taking the time to put it together...I learned something new today - 3 cheers to you!


    Bookmark   October 7, 2013 at 2:43PM
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ken_adrian Adrian MI cold Z5

jo ....

nems over winter in the crown ... since the plant goes completely dormant above.. so they travel up the center of the plant.. and are rarely on an edge ... yes.. i am sure there is the exception ... but that was the first reason i ruled it out when i looked at that pic ...

what do i win ....????

i have taken the MG class twice .... i wouldn't be quick to value highly.... the training ... if that was the ONLY qualification on a resume ... and too often it is ... i give them all the credit in the world for seeking knowledge .... but i am surprised peeps make money off it ....

9 looks like a rubbing injury.. but being so upright.. i cant figure out how.. unless you were holding the leaf up to take the pic ... blame some spring problem .... chafing ... dry skin ...


Here is a link that might be useful: maybe i will win a major reward?????

    Bookmark   October 7, 2013 at 3:14PM
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jan_on zone 5b

I made it into the 80% group, and I did recognize the brunnera since I have one that looks exactly like that. Question - are those the SAME KIND of nems that infect hostas? I hadn't thought about the possibility of that plant being dangerous to its neighbours. It's lower on the priority scale than the hostas so if it is indeed infectious it will have to go.

    Bookmark   October 7, 2013 at 3:52PM
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Steve Massachusetts Zone 5b


Yes these are the same foliar nematodes that are in Hosta, Aphelenchoides fragariae. Don't ask how to pronounce it. It's Latin. Brunnera 'Jack Frost' is notorious for nematodes. You can also find them in Ferns, Ligularia, Cimicifuga and some weeds.


    Bookmark   October 7, 2013 at 4:00PM
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josephines123 z5 ON Canada

Ahh, Ken...LOL re link...have you been saving that one (to use) for long? LOL. Hilarious...quick little gaffer at the end aspiring to become a ladies-man? Tee hee hee...however......for your latest educational tip, you win my gratitude....until I find the matching lamp! Lol

The second MG class was for refresher or...?? Kudos for going the extra mile to gain knowledge...of which you have plenty...Fortunate of us to be able to avail ourselves of it.

Thank you for the additional input re central path as it's easy to remember. I just wish I could get outside but will have to wait out the darn rain. I'm anxious to try out my newfound knowledge! :-). Now I'm wondering what precautionary measures should I take for all the potted hosta that will experience a move.......besides looking for tell-tale nematode signs.


    Bookmark   October 7, 2013 at 7:23PM
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jan_on zone 5b

Drat. I'm rather fond of 'Jack Frost' but it is just infested with nems, so I guess it has to go. I'll treat the spot with boiling water because I would really like to plant a hosta there. Thanks for the heads-up Steve.

    Bookmark   October 7, 2013 at 8:01PM
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newhostalady Z6 ON, Canada

Looking at #1-3, I had no idea of whether the plant had nematodes or not. But after seeing the photos and your explanation, I was able to answer #4-10 correctly. Now I have a much better idea of what I am looking for! Tomorrow I am going out to my garden to inspect it for nematode damage. I'm keeping my fingers crossed! If in doubt, I hope you won't mind if I post a photo. Thanks Steve for some great information.

    Bookmark   October 7, 2013 at 10:30PM
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ken_adrian Adrian MI cold Z5

to get your MAJOR MG AWARD ... lol ...

you need to put in volunteer hours...

so i take the class... start dating.. get married ..... babies come along.. i move 1650 hosta to a new garden .. life gets in the way.. etc ...

so 5 years later.. too late.. so i took it again ... this time at hidden lakes.. different county..

and .. lo and behold.... the same result.. lol ...

no major award ...


ps: i love the way he is running his hand up and down it and mom slaps it away ... lol..

    Bookmark   October 8, 2013 at 7:07AM
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