While guayule has been the subject of significant research and commercialization in the past, TKS is just now in the process of crop development, said Matt Kleinhenz, who leads the TKS breeding and agronomy program at OARDC.

This process started in 2006 with a small number of TKS seed collected in the wild. Roots of those plants contained 1.2 percent rubber on average. Growing in greenhouses, in high tunnels and in open fields, those seeds been crossed over the past few years, generating groups of plants that are continuously evaluated for characteristics such as growth rate, root structure and, of course, rubber yield. This year, Kleinhenz's research team produced close to 13 million TKS seeds from plants containing nearly 9 percent rubber on average.

These seeds are a unique collection that researchers hope will become the foundation for TKS as a crop.

So far, plants with roots containing up to 20 percent rubber have been developed, Kleinhenz said. By comparison, the common dandelion, Taraxacum officinale, produces little to no usable rubber. TKS has been planted and harvested in both spring and fall. Either way, the cold of winter appears to help to increase rubber content, he explained. Also, the plant requires few agricultural inputs, increasing its potential as a cash crop.

"It’s rare to have the opportunity to develop a new crop from scratch," Kleinhenz said. "It’s complex and requires a lot of work.

"But when we succeed, TKS will provide farmers in Ohio and beyond with another option to add to their crop rotations and make money. It will also generate jobs and additional economic activity from transportation, equipment manufacturing, processing and other activities in the supply chain."

TKS roots also contain inulin, a carbohydrate used as an additive in foods such as yogurt and which can also be converted to fuels such as ethanol and butanol.

More research still lies ahead to breed a plant with the right combination of agronomic characteristics that would make a suitable crop for farmers to grow. Other considerations, such as seeding rate per acre, are being worked out as well. Researchers are also looking for the most effective way to control weeds in TKS stands, since cultivation is out of the question because the plants lay too close to the ground.

"TKS is not going to survive as a crop without effective weed control," said John Cardina, an OARDC weed expert. "This plant is not very aggressive. As a weed, it’s actually a bit of a wimp.

"It doesn't grow fast and doesn't cover much ground, which means weeds can take up a lot of room quickly, taking away light availability, nutrients and water from TKS. Chemical control is our best option, but there's the challenge that TKS is closely related to things we now treat as weeds and that available herbicides kill."

Cardina has tested a variety of herbicides and found three post-emergent products that look like good candidates. These are herbicides currently used in crops closely related to TKS, such as lettuce and sunflowers. He said he hopes to have a package of weed management options ready next year, after running additional experiments.