University of Illinois research reports that several herbicides used on corn also have good selectivity to Miscanthus xgiganteus (Giant Miscanthus), a potential bioenergy feedstock.

“No herbicides are currently labeled for use in Giant Miscanthus grown for biomass,” said Eric Anderson, an instructor of bioenergy for the Center of Advanced BioEnergy Research at the University of Illinois. “Our research shows that several herbicides used on corn are also safe on this rhizomatous grass.”

M. xgiganteus is sterile and predominantly grown by vegetative propagation, or planting rhizomes instead of seed. This can be a very costly investment and requires a 1- to 2-year establishment period. Anderson’s research showed that Giant Miscanthus does not compete well with weeds during establishment, especially early emerging weeds.

“There’s a great cost in establishing Giant Miscanthus,” Anderson said. “It’s important to protect this investment, especially if it goes commercial. When weeds out-compete Giant Miscanthus, the result is stunted growth and lack of tillering. Basically, you are risking the crop’s ability to over-winter.”

The study, funded by the Ingersoll Fellowship, the Illinois Council on Food and Agricultural Research and the Energy Biosciences Institute, screened 16 post-herbicides and 6 pre-herbicides in a greenhouse setting. Several herbicides, particularly those with significant activity on grass species, caused plant injury ranging from 6 to 71 percent and/or reduced M. xgiganteus dry mass by 33 to 78 percent.

Researchers then narrowed these herbicides down to the safest options and evaluated them in field trials replicated over two years. Field experiments confirmed the greenhouse experiments. Pre-emergence herbicides and herbicides with broadleaf-specific activity generally did not produce significant injury or reduce aboveground biomass, while herbicides with considerable grass activity tended to cause injury ranging from 22 to 25 percent and reduce biomass by 69 to 78 percent.