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grandmothers_rose

How do I permanently kill native milkweed?

I planted native milkweed three years ago for the Monarchs. The Monarchs all, as in every single one, had OE so, last fall after two years of growth I decided to dig up the milkweed. This spring I have dug up shoots no less than four times, removing as much of the root as I could follow in the soil. I can tell the next time it pops up will be too near my perennials to dig up. What can I spray on the milkweed to kill it? Regular Round-Up sprayed twice on consecutive days did not phase it the least.

I truly understand the phrase "noxious weed" which is also used to describe native milkweed. I hope this post serves as a warning to other uninformed people who are considering planting it. In my opinion, native milkweed should never be recommended without a dire warning in the same sentence.

I also grow butterflyweed, tropical milkweed and swamp milkweed that appear to be ok.

Comments (22)

  • grandmothers_rose z6b
    Original Author
    11 years ago

    It is Asclepias syriaca. Pictures in my Weeds of the Northeast book look just like it.

    Terrene, please forgive my rant, it's not directed at you and I appreciate that you confirmed the method to eradicate it.

    I posted here because I planted it on the advice of numerous posts saying it was a good host for the Monarchs (which it was.) Some people did say it could get out of control, but I didn't know it would grow from roots thinner than a pencil 6 feet away from the mother plant 6 months after the mother plant was dug up. Even mint is easier to eradicate in my garden!! I went out for the fifth time this morning to dig up more rhizomes. I am doubly frustrated because of its persistence and because all the Monarchs had OE. If the Monarchs had been healthy I could have dealt with the milkweed issue better. I dare say I'm a bit bent out of shape because the rhizomes are in my rose garden, now, instead of the annual part.

    The weed book says to keep mowing it, too. So I'll continue to dig where I can and just break off the shoots when they sprout.

    I will plant more of the tropical milkweed this year. I know it will die over the winter! Does it have any bad garden habits? Self seeding is fine, I just can't take the persistent roots.

  • runmede
    11 years ago

    Our winters are cold enough to kill the OE. I'm 7A and looks like you are 6A. The common milkweed dies to the ground and comes up every year. Just cut the dead tops off in late fall and the shoots that come up in the spring will be OE free.

    All milkweeds will eventually get OE because it is carried by the butterflies. It is more prevalent in the fall. I wash my milkweed in tap water (my water is chlorinated). Then I dry it off and feed it to the caterpillars.

    I wish that I had time to hot link all these links. Just copy the url and put into your search engine.

    http://www.evansonart.com/monarchdisease.html
    Have you looked through this?

    http://www.learnaboutmonarchs.com/learnaboutoespore.html

    http://www.uga.edu/monarchparasites/whatisOE/index.html
    How to tell if butterflies are infected with OE

    An infected pupa may develop dark spots or blotches two or three days before the butterfly emerges. These abnormal dark areas are parasite spores. Spores form on the eyes, antennae, wing veins, but mostly on the abdomen. You can see the spores through the outside layer of the pupa a day or two before pigments that color the butterfly normally darken the pupa. Before a butterfly emerges from the chrysalis, pigments are laid down coloring the scales that cover the butterfly. This normal change in the color of the pupa is symmetrical. The color change of an infected monarch happens earlier and does not create a balanced pattern on the pupa.

    Here is a link that might be useful: My Monarch Guide Dreaded OE Spore

  • grandmothers_rose z6b
    Original Author
    11 years ago

    Thanks for the websites!

    Yeah. I did some research on the web and posted a few things here, too. Really, every single cat had OE. Many just died as cats, even in the "J" position, all chrysalises I found never hatched, all the cats were dull colored from the OE and it was worse at the end of the summer. Looked just like the photos on the web. All the bitty cats I took inside pupated but couldn't fly, and were still on the butterfly weed the next day. OE must be really bad around here (Shenandoah Valley.) The worst part is I had lots of cats, 50 or so.

    I saw one website that suggested carefully cleaning the eggs to remove the spores. I might try that this year if I find any eggs. I bookmarked it. I'll have to bleach/clean the milkweed, too. The info on cleaning the eggs is at the end of the website.

    I'll keep the butterfly weed and a couple tropical milkweed plants one more year. But the native, common milkweed has to go.

    Here is a link that might be useful: how to clean Monarch eggs

  • terrene
    11 years ago

    Grandmothers, I apologize if I came on a little strong, it was actually a little startling to read your post at first. In my yard and gardens, Asclepias syriaca pretty much grows where it wants, even in the middle of one of my woodland gardens in mostly shade! 2 years ago I "thought" I transplanted all of it out of that garden and to another spot - well that didn't work too well, it still came up as strong as ever, and is slow to establish in the new spot. Now I just leave it be and garden around it, because every year a few Monarch females find these plants and lay eggs on them and they make good food for the cats.

    Some of the milkweeds including A. syriaca appear to have the ability to sprout from sections of root that are left behind in the soil. It also pops up a few inches or feet over from where it was the previous year. So don't be surprised if it pops up now and then even after you've removed most of it. It's a plant for wilder areas but IMO it should be safeguarded for the Monarchs.

    Butterfly weed, tropical, and swamp milkweeds are much better behaved and stay put where you plant them! :)

    A pic of a female laying eggs on the common milkweed in the woodland garden, where it's growing amongst the violets, Lunaria, and woodland phlox -
    {{gwi:459233}}

  • grandmothers_rose z6b
    Original Author
    11 years ago

    Terrene, I still have some seeds (stored in the fridge) that I used to grow my milkweed. Want some? They grow into super vigorous plants! ;)

    Or maybe it is the cow manure compost that the milkweed likes so well . . .

  • terrene
    11 years ago

    Thanks grandma, but I've got plenty of A. syriaca seeds. I collect it from wild patches around here and scatter seed and share seed on the Seed Exchange. I keep a mental log of significant patches around here, because I use wild sources of milkweed as supplemental food for the cats as well places I can collect eggs and larvae!! :)

  • drsonja99
    11 years ago

    Is there anyone willing to give me or sell me some different types of milkweed seeds? Thanx
    Sonja

  • grandmothers_rose z6b
    Original Author
    11 years ago

    I have some of the INVASIVE common milkweed and some tropical milkweed. You should be able to e-mail me through gardenweb and I'll mail some to you. I didn't have any trouble sprouting either one and the common milkweed has been in my fridge (already cold stratified) so long it should sprout the minute you put it in some dirt. Thre are some really good instructions on the web for sprouting milkweed.

    Here is a link that might be useful: how to sprout milkweed seeds

  • drsonja99
    11 years ago

    Is there anyone that I can get some milkweed seeds from? I would love different kinds and colors!!! If anyone willing to sell or give seeds please email drsonja99@yahoo.com
    Thanks!!

  • nel.nucifera
    11 years ago

    Drsonja99,

    Have you tried the GW Seed Exchange? There are MANY users there who would LOVE to trade seeds with you.

    Don't forget to read the Special Instructions for the Seed Exchange, first. If you have any questions just ask! Gardenwebbers are really helpful people.

    -Nel

    Here is a link that might be useful: GW Seed Exchange Forum

  • Cherz_132
    11 years ago

    I have common milkweed throughout our small suburban garden. It does spread and when I need to trim it, I do. I find the monarchs really like the tender shoots anyway. I love the smell when it blooms and I have had my only sighting of a banded hairstreak on the bloom!

  • runmede
    11 years ago

    Don't just blame the milkweed. It may be your containers. Those need to be bleached too. This year I ended up putting some bleach into my washing machine and turning off the wash cycle. Make sure you use cold water. Hot water will kill the bleach. I put my containers in there to bleach them. Then, I rinsed them in the large tub near the washing machine with hot water. Then, further washed with them with dish washing detergent. Then, rinsed them again with hot water. Then, some cold water. You need to make sure you get all the bleach and soap off. Those will kill the caterpillars, too. I'm in Herndon, VA. Probably about an hour from the mountains.

  • terrene
    11 years ago

    Drsonja, feel free to check out my exchange page below and send an email if you want milkweed seeds. I have seeds for several species of Asclepias that you can get by doing a SASBE/BEAP (self addressed stamped bubble or bubble envie and postage). Instructions are on page.

    Here is a link that might be useful: terrene's exchange page

  • jazzygardener
    11 years ago

    Milkweed is the only plant that the monarch butterfly will lay her eggs on. I have it planted in my garden and I encourage my neighbors to do the same. If you want to keep it from spreading dig a drench around the area that you have it planted and sink that heavy black plastic landscape edging at the root depth. This will keep the roots from spreading.

  • kathytnj
    11 years ago

    Round-Up will kill butterflies. Monarch Watch or the National Butterfly Association, can't remember which, recommends using vinegar to kill your weeds.

  • kmarissa
    10 years ago

    I hope it isn't rude of me to resurrect a thread from a few years ago, but I came across this thread while searching for information on controlling asclepias syriaca, more specifically, whether the rhizomes can be contained so as to prevent them from taking over (the seeds I'm not as concerned about).

    I have a couple of 1 year old syriacas in my garden (planted last year), as well as some new syriaca and purpurascens seedlings I have started indoors. I'm just now realizing/reading about how aggressive established syriaca can be. I have been fighting ongoing battles with Japanese knotweed and bindweed in my garden, which makes me very leery of inviting more rhizome-related trouble! I also have a fairly small garden, which means that if the syriaca begins spreading, it will quickly be popping up in my raised veggie beds on the one side, or in my rose/perennial beds on the other side.

    That said, is there a way to contain the syriaca rhizomes? Jazzygardener, above, mentions black plastic landscape edging--do others recommend this approach? Perhaps I'm overly cautious because of my J. knotweed experiences--those roots spread far too deeply underground for some black plastic to do much good, but J. knotweed is somewhat notorious for that so it may not apply to syriaca. If black plastic would work, what about large nursery pots sunk into the ground?

    Or alternatively, might it be a better idea for me to focus on better-behaved asclepias that would be more manageable? As mentioned, I do have some purpurascens seedlings and from my reading, it looks like there are many other asclepias varieties that are better behaved. I don't want to do the butterflies any disservice, but I don't know if I can take on another garden battle! What would you recommend?

    Thanks all for any thoughts and opinions. :)

  • runmede
    10 years ago

    Asclepias incarnata (swamp milkweed) clumps and does not run.

    You can plant tropicals so that you will have some food this year. In 7b, you would not have a problem with them being invasive.

    I saw someone put down some plastic landscaping edging around the stand of milkweed and the common milkweed clumped instead of running around everywhere.

  • ellsberg
    6 years ago

    I have commen milkweed in my garden. The roots go down up to 2 feet deep. My front yard looks like an archeologist dig. Covering with mulch does not stop this plant. Its a monster. I,m going to try soap and vineger. Wish me luck.

  • mblan13
    6 years ago

    Try this. Put on a pair of rubber gloves to keep the chemicals off your skin, take a pair of cotton gloves and soak them in grass and weeds killer and put them on OVER the rubber gloves and rub the plant between your hands. You can kill a weed in the midst of a beautiful patch of flowers without harming the ones you want to keep.


  • Jay 6a Chicago
    6 years ago

    Butterfly weed, Asclepius tuberosa, and swamp milkweed, Asclepius incarnata, are also native milkweeds. Can you see the O.E. spores on the plants? How do you tell that the other milkweed species aren't infected? Would spraying the plants with a mild bleach solution kill the spores? They recommend doing that for infected eggs.

  • KC Clark - Zone 2012-6a OH
    6 years ago

    Jay,

    The OE problem post is from 5+ years ago. Not going to get answers about the OE.

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