black spots on milkweed

[MNkristin]

Happy spring all,
I'm excited to start my 2nd season of monarch rearing. the milkweed is quite prolific this year. I have some that have black spots. I've been in this house for ~7 years and have never noticed black spots on the milkweed before. thoughts anyone?
thanks,
Kristin

[Mona Miller]

Which part of the country are you in? What species of milkweed?

Here on the east coast we've had way too much rain that can cause fungus.

[MNkristin]

I'm in Minnesota. I believe it's common milkweed. We had a VERY wet spring last year too, but I didn't have any problems- 'cept for the earwigs!

[Mona Miller]

http://www.hort.purdue.edu/newcrop/ncnu ... n82-88.pdf
Production Variables Affecting Follicle and Biomass
Development in Common Milkweed
Page 82, fourth paragraph, last sentence:
"Showy milkweed has been found to be highly susceptible to a bacterial blight and black spot fungus, while common milkweed demonstrates resistance to both."

http://www.dnr.state.wi.us/org/caer/ce/ ... windex.htm
Info also on ozone damage.

http://www.heyne.com.au/gardencentre/fa ... seases.htm
This website has some good pictures of the various problems with plants.

This year my hollyhock that is supposed to be disease resistant has rust. Go figure.