Bank Robber

Digital decision-aid tool helps farmers make withdrawals from their weed seed banks

Sonja Birthisel
Sonja Birthisel sets up a field experiment during the spring of 2016. Photo courtesy of University of Maine.

Farming is a growing sector of the Maine economy, with substantial increases over the past 10 years in the number of farms, value of agricultural products, and number of farmers under the age of 34. Respectively, increases of 17, 65, and 46 percent.

And many of those farmers choose to grow organically, motivated by deeply held commitments to environmental sustainability (organic farming practices are typically more environmentally benign than conventional practices).

Economic sustainability, however, relies heavily on a farmer’s ability to manage their weeds using organic methods, which can be tricky without the use of conventional pesticides and herbicides. Many organic farmers in the Northeast cite weed management as their foremost production challenge.

What makes it so challenging is the weed seed bank: the number of seeds stored in the soil. On the high end of the scale, there can be over 50,000 germinable weed seeds per square meter of soil 10 centimeters deep on an organic farm in the Northeast. That’s a lot of potential recruits to choke the life out of your crops and wither away your profits.

The best way to decrease the seeds in your bank, says UMaine Ecology and Environmental Sciences Ph.D. student Sonja Birthisel, is by “letting them germinate and then killing them.”

“There are lots of ways to kill them once they’ve germinated,” says Birthisel, “but seeds that are lying dormant in the seed bank are much harder to kill, and that’s why it’s a continuing problem for farmers.”

Thus, there is clear need by organic farmers for tools to help manage weeds effectively, especially tools that help a farmer target specific weed issues, like the pernicious Hairy Galinsoga—perhaps the biggest weed issue facing Maine’s organic vegetable farmers today.

To that end, Birthisel is on the team of a Mitchell Center-funded project that has created an educational tool known as “WEEDucator,” which is mathematically based and underpinned by real-world data collected by Birthisel, her adviser Eric Gallandt, and others.

Part decision-aid, part computer game, the tool allows beginning farmers to explore different weeding methods, learn more about the life cycles of common weeds, and includes an interactive model that farmers can use to manage their weed seed banks virtually—helping them learn through simulated ‘trial and error’ without the real-world costs.

The content of WEEDucator was developed with input from two focus groups of farmers. In developing the tool, Birthisel and her team made sure to include information that established farmers said they wished they had known when they started farming.

hairy galinsoga
Hairy Galinsoga. Photo courtesy of Joseph M. DiTomaso, University of California-Davis,

With a working prototype in hand after nine months of development, Birthisel recruited undergraduate students from UMaine sustainable agriculture classes to try WEEDucator. Using pre- and post-assessments, she says, “I found that their understanding of weed ecology and management increased significantly with use.” She notes that a majority, over 90 percent, indicated that they found WEEDucator helpful and fun to use.

She also asked students to rank ways they might like to learn this content. They indicated that lab and classroom activities tied with WEEDucator as the most preferred way to learn.

Birthisel also presented these results in the Teaching and Extension section at the Weed Science Society of America’s annual meeting, where it generated good conversations about the potential for new media tools to improve outreach communication.

“Though I consider WEEDucator to still be in a prototype form rather than a ‘finished project,’ it is freely available for download and use,” says Birthisel. To download the tool, visit the WEEDucator site.