The Spring 2016 issue of Olbrich Botanical Gardens' newsletter arrived at the end of last week. It contained a short but very disturbing article. Olbrich is suspending their annual leaf mulch sale. The Wisconsin Department of Natural Resources is recommending that leaves not be spread throughout Dane County due to the possibility of spreading the invasive and highly destructive jumping worms (Amynthas app.), according to the newsletter.
Typically Olbrich gets massive amounts of local leaves helping the city keep them out of landfills. Olbrich turns them into wonderful mulch that I've been buying just about as long as they've been selling it. It is a great product and an important source of revenue for the gardens. Jumping worm cocoons have been found to survive the winter in Wisconsin and can be spread through soil, compost, and mulch (hardwood and leaf), according to the Olbrich web site.
Dane Country is at the western edge of the section of southeaster Wisconsin where the worm has been reported. They were discovered in the UW-Madison Arboretum in 2013. To find out more about the worm, what it looks like and what to do if you find it in your garden, visit the DNR website here. You can print out a jumping worm identification card and a brochure from the site.
A newly planted and mulched bed in 2010.
The worms are long (a gardening friend measured one at 11 inches!), and slither and jump like snakes. "They change the soil by disrupting the natural decomposition of leaf litter on the forest floor. They turn good soil into grainy, dry worm castings (poop) that cannot support the understory plants of our forests. In residential and urban areas they can also harm ornamental plantings and turf," according to the DNR site. This is very serious stuff and besides, the worms are creepy. I have learned to live with many critters during the years I've gardened but snakes have never been one of them.
On the heels of that news came word that the West Side Garden Club will not be selling plants from member's gardens this year for the same reason: to avoid potentially spreading this invasive worm. They will sell the plants that they get from a commercial grower since those folks use sterile potting soil. This is a blow to gardeners as the West Side sale is one of the best in the area. All of my wonderful Primroses have come from there. Not only that, but the organization — like most local garden groups — donates the profits from their sale to public gardens like Obrich and Allen Centennial Garden to name just two. I've also talked to some members who say they will not buy any plants at local plant sales that come from area gardens because of this issue.
The worm is a recent enough problem that there is not enough research to suggest any solutions at this point. Bad news any way you look at it and not the way any of us want to begin the gardening season. Makes all those big yellow x's marking the Ash trees to be removed in the onslaught of the emerald ash borer seem not so bad.
Mark dumping a load of Olbrich mulch in our driveway a number of years ago.