This year, for the first time in the 10 years I've been in the Cincinnati area, I noticed a leaf blight on Amur honeysuckle (Lonicera maackii), which is the #1 invasive plant in the region. I collected a sample and had it analyzed by the University of Kentucky Extension Service, which identified it as honeysuckle leaf blight caused by the fungus Isolibasidium deformans. I posted a query and pictures to the Midwest Invasive Plant Network (MIPN), and reports of the blight came in from all over the Midwest. I was also contacted by Jerry Riffle, a retired plant pathologist from the USDA Forest Service Rocky Mountain Laboratory. He had published a chapter in RM-GTR-129, Diseases of trees in the Great Plains, entitled "Honeysuckle Leaf Blight," available at http://nac.unl.edu/diseasetrees/chap11.pdf, and he had identified the symptoms in the pictures I had posted as honeysuckle leaf blight even before I received the diagnosis from the Extension Service. This blight affects all honeysuckles; Amur is supposed to be more resistant.
Last week, I was on vacation in New England. I saw the symptoms there on Tatarian honeysuckle (L. tatarica) in western Massachusetts in Richmond, which is on the border with NY, and also in eastern MA in Ipswich, which is on the coast. On the way back home, I also saw it in far western NY, in Perrysburg, which is near Fredonia. Have other ecologists seen this in other regions and on other species? My 2009 review on invasive shrubs in the US (J. Sust. For. 28:152-217) found 7 invasive Lonicera shrub species in the US (L. fragrantissima, L. maackii, L. morrowii, L. standishii, L. tatarica, L. xylosteum, and L. x bella). If you've seen it your area on an invasive or native Lonicera species, please report it to me. I'll compile and post the results to the list. Why is it appearing this year? Much of the US had a very mild winter in 2011-2012, so perhaps more spores survived. Perhaps the fungus has adapted to species that are now quite plentiful in many areas. It remains to be seen what effects this will have on growth, mortality and reproduction in honeysuckles. So far, I have seen it primarily on this year's growth of L. maackii, not on older growth. It's still too early to tell if the leaf death caused by this blight will affect the shoots. Cheers, Rick ================================ Richard L. Boyce, Ph.D. Director, Environmental Science Program Associate Professor Department of Biological Sciences, SC 150 Northern Kentucky University Nunn Drive Highland Heights, KY 41099 USA 859-572-1407 (tel.) 859-572-5639 (fax) boy...@nku.edu<mailto:boy...@nku.edu> http://www.nku.edu/~boycer/ ================================= "One of the advantages of being disorderly is that one is constantly making exciting discoveries." - A.A. Milne
