Barb Liukkonen, Water Resources Extension Coordinator

Of course, you wouldn’t do that on purpose - you’re probably careful to select and plant native species. However, hitchhiking exotics might come along with those native plants that you are planting to improve the shoreline.

Recent research, funded by Minnesota Sea Grant and MN DNR found that 92.5% of wetland and aquatic plant orders included unintended plants or animals! Kristi Maki, advised by Sue Galatowitsch, in the University of Minnesota Horticulture Department, studied how often and what types of invasive species came along with plant orders, how easy it was to obtain regulated invasive plants, and how certain species are adapting to our colder Minnesota climate.

In the first phase of her research, Kristi surveyed which exotic aquatic plants are sold commercially. Her database, including 119 vendors and 39 invasive aquatic plants, showed that more vendors sell aquatic plants via the internet than from mail order catalogs and that 6 regulated aquatic plants and 4 regulated terrestrial plants (sold as aquatics) are commercially available.

Then Kristi placed orders with a variety of vendors across the US. She ordered individual plants or assemblages from water gardening or aquarium specialists and general garden businesses, with 30 vendors outside Minnesota and 4 from within the state. Regulated species were ordered 14 times and were received, without question, in all but one case!

When plants arrived, Kristi carefully examined them and identified unordered hitchhikers that were hiding in the packaging, tangled in roots, or included in the soil. Here’s a very brief summary of what she found.

• 90% of the purchases contained plants that hadn’t been ordered
• 80% included animals (usually invertebrates, but twice she received live fish!)
• 62.5% included algae, moss, or fungi
• 41% included seeds

Many of the hitchhikers were viable plants or seeds, as Kristi found when she planted them. In some cases, hitchhikers were federally regulated plants, including purple loosestrife, hydrilla, curly pondweed, and giant salvinia. It turns out that the unintended transfer of illegal species only occurred about 10% of the time, but when you think of how many plants we’re planting to restore shorelines, there’s a huge potential to introduce invasive exotic species.

So, what can you do to help stop the spread of invasive aquatic species as you are restoring a shoreline or cultivating a water garden?

• Learn what exotic species look like
• Be careful when sharing or transplanting plants (remember you need a permit to move plants from one part of your lake to another!)
• Order from reputable growers and ask how they prevent hitchhikers when they package or deliver plants
• Expect your plant sources to follow the laws and use sound practices
• Don’t order via internet web sites without evidence that they’re concerned about exotics
• When you receive plants, carefully examine them to remove hitchhikers before planting Never introduce anything from your water garden into a stream, lake, wetland, or drainage ditch.

Posted in Care of Shoreland Property |