A. incarnata - disease process?

Greensboro, NC(Zone 7b)

Hello - I have 5 swamp milkweed near each other. A single stalk on one plant developed a dark, bluish black tinge and the leaves developed mottled, dark, irregular spots. I cut it off at the base, but I see another stalk is beginning to develop the same dark color.

This is starting at the base of the stalk, not the top. The foliage at the top of the second affected stalk has not started to show any sign of the progression.

Does anyone have any idea what this could be? None of the other plants are affected as yet.

As I garden for wildlife and the milkweeds are for the monarchs, I cannot do anything chemical to prevent this. Any ideas/help will be appreciated!!!


Fort Worth, TX(Zone 8a)

Can you post a picture so we have a better idea?
I remember the first year I had swamp mw it drooped and looked sickly, I was not pleased at all. This year it looked fine until a swarm of Swamp MW Beetles eat it to a numb!

Cincinnati (Anderson, OH(Zone 6a)

I had one stalk of an A. encarnata do that and I thought maybe it was some root borer animal like a vole. In any case it was just the one on the edge of the garden and the others seem fine.

I have heard of gardeners having nemotode issues and also bacteria in the soil that causes wilt on Milkweeds, but if your other plants are OK you could probably rule that out.

Greensboro, NC(Zone 7b)

Thanks. We do have an awful lot of rodents this year. A couple of A. tuberosa nearby have suffered wilt and collapse. I suspected because of them.

I didn't have any problems last year until late in the season and that was from aphids on the A. incarnata. Thanks for your thoughts.


Southeastern, NH(Zone 5b)

I wish I could tell you what the problem is. I lost every single one of my Asclepias incarnata to some kind of disease and have no idea what. I kept trying to plant new plants in that garden every year and they just don't come back. I haven't had any probles with my A. tuberosa though. I think my soil is too dry for them and combined with a disease they just can't grow for me.

Greensboro, NC(Zone 7b)

All of the stems are beginning to turn a bluish black at the base. There are 3 large healthy (as far as I can tell) plants around this one. Can't exactly pull it up or spray or anything since they are intended to be eaten!!!

I don't see any signs of insects or fungus. Stumped.

Meredith - maybe you should determine what types of milkweeds are native in the northeast.

Bobby, proprietor of Butterfly Encounters will tell you which might work for you. He may also have an opinion about why they didn't come back. That reminds me - I don't think I asked him his opinion on what might be wrong with my plants! ;)

Thanks for the reminder.


p.s. here's the link


they are on FB also - he is very prompt with replying to communications. Good luck!

Southeastern, NH(Zone 5b)

Asclepias incarnata is native to almost the entire continental United States including here (minus 7 states with 5 being on the west coast). It's not a hardiness issue, the original plant I planted, made it here no problem for a couple years. It is definitely some kind of disease and I had tried researching diseases of Milkweed but there isn't much info out there about it. Probably because most people think it's a weed! lol

Cincinnati (Anderson, OH(Zone 6a)

Bobby has a cute butterfly website.

It's become much more elaborate (and his facebook page too) than a year or so ago! Looked at his videos on growing asclepias seeds and he makes it seem pretty simple. Not always my experience, though! (Like he doesn't mention those heat mats can get hot hot hot!)

I wonder if he was the guy who was asking for all the different milkweed seeds here on DG and GW?? I'm thinking he is. Must check into that.

I have lost a few A. incarnata because they were in too dry of a site too. And I think those nasty nematodes can be debilitating. Had to relocate my milkweeds to different areas of the yard. Well, I didn't transplant, I started from scratch with new plants and seedlings. So far OK. What I think were the nematodes went after my daisies like crazy too.

(BTW, I have seen only one Monarch cat in my garden so far this year and that one got snapped up by the birds. Have you guys had better luck?)

Greensboro, NC(Zone 7b)

I have only had 1 monarch sighting in my yard and that was late April - which was very early for me. I don't know why but we don't seem to get much traffic until August. My butterfly weed was only 3"-4" out of the ground at that point, so I was pretty impressed that it was able to find them. I didn't note any eggs. Have only seen 1 cat and that was of a swallowtail on my dill.

I don't know what's going on with my milkweed. They don't seem to have the same kind of root system as A. tuberosa so may be easier to move. What happens when nematodes come - tell me about the symptoms? Can't do any kind of anything in terms of chemical treatment when you garden for wildlife. It is not particularly wet/swampy where they are planted either. Doubt that drought would be the cause of it.

I also grow several other milkweeeds. Currently have A. curassavica, A. purpurescens, and A. exalta seedlings soon to go in the ground. I ran out of physocarpus seed. I think I let them get too dry out there in the sun. I am behind this year due to a hand injury. The crabgrass is getting on my nerves. I can't call them weeds anymore because most of what I plant are considered weeds (natives)!

I have never tried heat mats - when I get my stuff started early it's usually in a milk-jug greenhouse outdoors in about February. Have you tried that? For the cold/moist stratification this year I ordered seeds and put them into the fridge in November. I brought them out in February (?) or March (?) intending to plant them. They began to sprout inside their plastic baggies right there on my kitchen counter.

I doubt that Bobby is on here for seeds. Have you ever purchased from Onalee? She has some great stuff available for butterfly/wildlife gardens and shipping is free. Check her out. She's in the Garden Watchdog and her site is easy to find online - do a search for Onalee seed.

Well best get to whatever it is I'm going to be doing today while hiding inside out of the sun/heat. I'm such a wuss in the summer. :/

Have a good one!


Cincinnati (Anderson, OH(Zone 6a)

Found this listing of issues that Asclepias can be bothered with. Quite extensive and includes nematodes and viruses:

Agriculture Handbook 165 (1960) lists the following as affecting this species: Alternaria sp. (leaf spot), Ascochyta asclepiadis (leaf spot), Cercospora clavata (leaf spot), C. elaeochroma, C. hanseni, C. illinoensis, C. venturioides, Diaporthe arctii (on stems), Didymella cornuta (on stems), Diplodia asclepiadea (on stems), Erysiphe cichoracearum (powdery mildew), Clomerella fusarioides (anthracnose, leaf and stem blight), Phoma asclepiadea (stem blight), Phyllactinia corylea (leaf spot), Phyllosticta cornuti (leaf spot), Phymatotrichum omnivorum (root rot), Puccinis bartholomaei (rust), P. seymouriana, Rhizoctonia solani (root rot), Scolecotrichum asclepiadis (on leaves), Septoria asclepiadicola (leaf spot), ?S. cryptotaeniae, S. incarnata, Sphaeropsis sphaerospora (on stems), Stagonospora zonata (leaf spot), and Uromyces asclepiadis (rust).

Nematodes: Meloidogyne incognita, Pratylenchus penetrans (Golden, p.c. 1984). Mosaic virus and Yellows virus are also listed. According to Campbell (1983), there is no evidence of major losses due to insects or disease; however, aphid infestations and viral infections appear common,

For me the Nematode thing can first be identified by the wilting of random plants. Then if you dig them up you can often see them on the roots (ick). You really have to follow a certain routine to rid the area of them~~these directions are available on the internet here and there. I think there is a way to do it with out harsh chemicals. Transplanting the asclepias to a new area is not really an option since the nematodes will move with it.

Yes, I love Wintersowing and have been able to start many rare-ish perennials that way after being a klutz with traditional seed starting. I have tried different iterations of it in the past five years and have settled on a successful routine modified from the GW wintersowing lady whose name I can't recall at the moment. I don't generally do HOS unless I'm really rushed.

Sometimes I get interested in planting seeds in mid-summer, etc. though too (when I lust after everyone's interesting gardens here on DG and GW). Then I have had good success with the Deno method which doesn't take up much counter or refrigerator space which is a concern for me. I don't do much direct sowing because the birds and rodents get to the seeds before they can germinate.

Yes, I like Onalee's seeds too. She has often shared astute advice on seed sowing and gathering here on DG forums and I have learned a lot from her. Everwilde and Prairie Moon have lots of natives for my region too and so I've gotten hooked on them as we are turning our backyard from lawn into a natural/native space slowly but surely. For the past five years we have been loading it up with lepidoptera friendly plants wherever we have a sunny patch.

Fairly hot here today and I see that the gardens need sprinkler water for the first time this year so maybe I'll do that. Then have one of my new berry concoction cocktails: smashed raspberries from the garden, pelagrino, vodka, and St. Germain on crushed ice, topped with some mint from the garden. A little decadent, but we're not going on vacation so I can splurge!

Good luck with your plantings and the Monarchs.

Greensboro, NC(Zone 7b)

Holy Lepidoptera!

I would like to be at your house for one of those tall cool refreshing drinks. :D

We have decided that the soil at this house we are renting just sucks (can I say sucks on DG?). Rust on my hollyhocks, powdermildew everywhere for the last 2 years. I tried to space things better that are susceptible in the hopes I can avoid some.

Wish me luck. ;)


Southeastern, NH(Zone 5b)

All this talk about Swamp Milkweed made me want to get another one. So I went to a nursery I had a feeling would have some and picked up a large one in a gallon pot. All of theirs had black spots on the leaves and I asked a youngish girl (probably college age) about it. She said they always get it and I do remember having it on my plants even before they started completely dieing. I think some leaf spot on them is inevitable similarly to Rudbeckia. Which is what her explanation was. However whatever I have in my butterfly garden, was actually killing the plants where leaf spot is usually not a cause of. So I'm going to try a copletely different spot like you Tab.. I just am having a hard time finding one. I've planted most visible areas of my yard already!

Greensboro, NC(Zone 7b)

Towards the end of the season my swamp milkweed do get spots. This turning black at the base is new though.
I am going to speculate nematode for lack of any other match to symptoms. If anyone turns up info on how to deal with them organically/sustainably could you please forward? I am also looking and will post if I find...


Southeastern, NH(Zone 5b)

Please do!

Cincinnati (Anderson, OH(Zone 6a)

Yes, I wish all my DG friends could come over to sample one of my summer cocktails~~and then walk around the garden and diagnose all of my issues and tell me how to make it look better! I'm a little down on my garden this year~~too many random out of place plants (I call it plant acne), not many in bloom, not many butterflies, and the deer got all my fancy daylilies. I'm ready to take up Bridge!

Back to Asclepias, I have to say I started a bunch of tropical milkweed seeds earlier this summer and now I have a big crop of them coming in to bloom just in time for the monarchs major 'flight' here in southwestern Ohio. I also have my Liatris ligulystylus coming into bloom and lots of zinnias (benary giants) from seed, so I'm hoping if there are any Monarchs in my township, they all find their way to my garden!

If anyone finds out the secrets of keeping the A. incarnata happy in the garden, pls. let me know. Mine are looking funky right now too!

If anyone is coming thru Cincinnati, please let me know, too! I'll break out the cocktail shaker! t.

Greensboro, NC(Zone 7b)

Yer funny. :)

Like you, I have random out of place plants, but that's what folks here on DG call a cottage garden, methinks. ;)

If it makes you feel better, I haven't seen but 1 monarch and not many others at all until fairly recently. I have been thinking that it may have been all the rain we have had on the east coast this spring (and now summer too!).

The last 3 seasons (the ones I've been doing Monarch Watch) my first Monarch was not till mid august! So my first sight in April this year was pretty exciting. If they laid any eggs, I don't know - my A. tuberosa was barely 3" out of the ground.

The swamp milkweed likes moist soil and full sun. It gets full sun here, but not so much moist soil. Towards the end of each season I've planted it it has collapsed somehow from somethin. Usually it's aphids. Not familiar with this turn and since I garden FOR the bugs I can't very well go in and kill any bugs that are killing plants. Unless I somehow find an unobtrusive way of dealing with potential nematodes.

I haven't done any research yet. Will start that just as soon as I get past this kidney (bleck) infection.

Have a groovy day.


Crofton, MD(Zone 7a)

My Asclepias incarnata has some weird looking leaves, too. This is the second year they have had this.... whatever it is.

Thumbnail by 2gardenkate
Greensboro, NC(Zone 7b)

Yep - that happens here too.

The 'disease process' I'm inquiring about is different from the leaf spots. Will post if I find any news!

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