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.