Knowledgebase
Asclepias Tuberosa Leaf Curl #841223
Asked July 18, 2023, 6:39 AM EDT
A family member added several Asclepias tuberosa plants to the south side of her house this year.
They were planted as 2” plugs. The soil is clay, the plants get full sun, everything in that garden is watered with a soaker hose that lies beneath the mulch. The plants have not been fertilized and no herbicide or pesticide has been applied. All of these new milkweed plants have developed leaf curl to one degree or another in the month or so since they were planted. The plants nearby - some small bushes and a few small flowering plants - look fine And are growing well.
I uncurled the leaves and checked for aphids and found a very few black ones on a couple of the plants but not on the others. I removed the aphids with sprayed water. I did find some black smudge on the bottom of one leaf but nothing else. Aside from the leaf curl on the newer growth most of the other, older leaves seem ok.
My questions are these - could this be just aphid damage (there don’t seem to be enough of them to cause this) or is there another potential issue? Perhaps the heavy clay content? Would it be beneficial to snip the affected leaves and dispose of them or will that stress the plants even more? other suggestions?
Kent County Michigan
Expert Response
Hi Katie,
Unfortunately, I don't have a straightforward answer for you. After consulting with several horticulturists, the general recommendation is "wait and see." I know that's probably not what you want to hear, but since we can't determine the exact cause, it's best to keep an eye on the plants. Keep scouting them, watching for insects or other symptoms. With more information, we might be able to figure out the cause, or the plants might grow out of it.
Asclepias tuberosa do not like transplanting. They often suffer for the first season after planting, but come back strong the second year. The symptoms could simply be a result of transplant shock.
There is a chance that the damage to the new growth was done by insects before the plants were purchased. Perhaps there was an insect infestation at the nursery, it was treated, but the damage to the developing tissue was done. It's virtually impossible for us to know. If this is the case, it should grow out of it.
Here is a link to more information about Asclepias tuberosa.
I don't think this is playing into the symptoms you are concerned about, but please let your family member know that Asclepias tuberosa does not like a lot of water. Soaker hoses, plus mulch, plus clay soil, could mean the plants stay too wet. You can send them the plant profile that I linked above.
Please keep an eye on the plants. If you see decline or other symptoms develop, please feel free to write me back. I can send the question to another expert.
Lindsey K. Kerr, MS, MHP (she, her, hers)
Consumer Horticulture Educator
Michigan State University Extension
