“Regardless of where you are, regardless of financial resources, you should be able to construct a solar tent,” Stapleton said. “Most of the materials needed – rocks and sticks – are easy to find on site.”

Air temperature inside the sample bags rose to 158 degrees Fahrenheit. Over the three days of the experiment, the rhizomes were exposed to temperatures 140 degrees and higher for 10 hours. None of the rhizome segments treated for three days in the solar tents sprouted. In contrast, rhizomes maintained in clear vegetable storage boxes and kept indoors for comparison all sprouted.

UC Cooperative Extension advisor Carl Bell, a San Diego area weed expert, tested the process in Lakeside, east of the San Diego metropolitan area, where a group of volunteers were working on restoration of the San Diego River.

“There are a lot of sites in California where volunteer groups are going into canyons and other remote spots to clean up weeds,” Bell said. “They’re going to places with no roads or trails, scrambling over rocks to clean up these areas. They could construct one of these tents and return in a week to find everything in the bags overheated to a point where seeds won’t germinate and rhizomes are dead. They only have to carry out the plastic bags and tarps.”
For the demonstration, volunteers pulled weeds and built solar tents on a parking lot. They invited the public to a workshop at the site a week later.

“When we pulled out the bags of treated material after a week of cooking, it was a gooey mass of vegetative material incapable of regenerating the weeds,” Bell said.

A diagram for building a solar tent can be found at http://ucanr.org/solartent.