Sunday, September 27, 2015

Tropical milkweed or not?

The debate continues. Should we plant tropical milkweed (Asclepias curassavic) for monarchs or not? Yesterday, I observed an entire flower bed neatly planted with the species at Mueller Austin,  a high-density development designed with sustainability in mind. After attending last weekend's Texas Pollinator Powwow in Kerrville, I'm of the opinion that we should not this species. 

That's because I listened to Dara Satterfield discuss research findings related to the nonnative species. She's with the Monarch Health Project, a citizen science project being conducted by Satterfield and other biologists with the University of Georgia. 

According to the project's website, participants "track the prevalence of the protozoan parasite Ophryocystis elektroscirrha (OE) in monarch butterflies. This parasite does not infect humans but can make butterflies sick: Monarchs infected with OE may be too weak to emerge properly from their chrysalises and can die at this stage. Or, infected monarchs can look completely normal but cannot fly as well or live as long as healthy monarchs."

What the research is showing is that "tropical milkweed in warm areas can encourage OE," Satterfield said last weekend. To protect monarch health, she also said, cut the tropical milkweed to the ground in the fall and even cut it monthly until spring. 

What I took away is that we should plant only regional milkweeds. Better yet, plant native milkweeds from seeds that originate in your area. I confess that I haven't adhered to that strictly. In fact, at the Powwow I bought an Asclepias tuberosa, which is native to Texas but not Central Texas.

After James and I got home from Kerrville, I cut our two tropical milkweeds nearly to the ground. I may even pull them up. I just haven't  quite decided yet....... 


TexasDeb said...

Sheryl: How does the trop milkweed encourage OE? Does it harbor it between butterfly visits or is there something intrinsic to the plant itself ? Are the plants "carriers" of some sort? I don't think I had any monarchs this spring but I do have some trop milkweed that came back after being frozen to the ground this winter. It grew back and is finally blooming (complete with aphids of course) but if there is something in the plant itself as opposed to plants that are receiving repeat visits from monarchs, then I'll certainly cut it off. I bought it "for" the monarchs after all.

Sheryl Smith-Rodgers said...

Deb, here's a page with more info on OE:

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