By ANN HINCH
Assistant Editor

KANSAS CITY, Mo. — What if the next big hope for ethanol turns out to be a parasitic invader for the same area it’s supposed to financially boost?
With so much talk about cellulosic ethanol someday being able to fill the biofuel gap that corn alone cannot supply – as well as the federal government’s mandate that 16 billion gallons be produced from cellulose annually by 2022 – it seems the common sense thing to do may be to find whatever grasses and plants can be grown prolifically and seed them where there is space.
But Dr. Jacob Barney cautions against doing this without first conducting a weed risk assessment (WRA) on a region. Barney, a postdoctoral weed scientist at the University of California-Davis, spoke about the importance of WRAs at the National Corn Growers Assoc. Corn Utilization and Technology Conference on June 4.
Barney noted the ideal energy crop needs: to be able to grow on marginal land, not prime soil which can be used for food crops; to be perennial so it doesn’t have to be replanted every year; to grow in great mass, to get the most value out of the plant; and to require little water and fewer fertilizers and chemicals to grow. The ideal cellulosic energy crop needs to be almost impossible to kill.
This, Barney explained, makes the ideal energy crop much like a weed. As farmers know, uncontrolled weeds can choke out more desirable flora. Just ask southern growers about kudzu. Or, ask California and Texas farmers about giant reed, where he explained it covers thousands of acres – and not just on marginal land.
What these two invasive species have in common is that at one time, they were deliberately introduced onto American soil for a positive purpose. Japanese Kudzu was planted as erosion control because it blankets the ground so thoroughly. Giant reed, native to Eurasia, was planted in the southern U.S. and is a source of musical instrument reeds and building materials.
By “invasive,” Barney said the federal definition is any non-native species deliberately or accidentally introduced into an environment by human agency, which causes economic and environmental harm or harm to human health. He added 42 percent of the threatened and endangered species worldwide are at risk because of invasive species.
He said switchgrass, considered desirable for cellulosic ethanol, has the same basic characteristics as the giant reed, when evaluated on the Australian WRA. So far, it is the only country Barney knows is using a formal assessment, which he said has also been tested in other countries and the U.S. and is “quite robust” in predicting the likelihood of a non-native plant becoming invasive.
“(Other researchers and I) used this assessment due to its broad applicability and widespread adoption as the standard WRA,” he explained, saying its results seem about 90 percent effective. “It was designed for ornamental/agricultural plants primarily, so we modified a few assumptions for our assessment of biofuel crops.”
In a recent issue of the journal Invasive Plant Science and Management, an article about the Australian WRA’s potential usefulness to Florida noted that across the U.S., preventing and controlling invasive plants costs approximately $34 billion annually. It also stated that not every non-native plant becomes “invasive” to its new host region.
Barney made this point, too. “For example, giant reed is a terrible weed in California and Texas, but may never become a weed in South Carolina,” he explained. “However, we need a series of experiments to address this hypothesis, because just stating ‘it’s not weedy here now’ is not sufficient.”
According to Barney’s research, if the modified WRA were used to make cellulosic planting decisions, giant reed would be rejected for planting in Florida, but miscanthus would be fine for anywhere in the country. Switchgrass would be rejected for California (as it is much like the giant reed; see above) – in fact, it’s on the state’s noxious weed list.
“I certainly have no rules for assessing when anything is ‘safe,’” he stated. “I am more interested in ensuring that assessments are performed to ensure a reasonable level of thought and evaluation has gone into determining and subsequently mitigating any potential negative consequences of growing dedicated bioenergy crops.”
On top of this, there’s genetic modification to consider. Hardiness, high production, resistance to drought – “These are fantastic goals from a agronomic perspective,” Barney said, suggesting breeders and crop geneticists might consider WRA evaluations when designing a plant.
“We can’t just throw our hands up and say ‘We can’t plant any of these!’” he explained. “I’m not suggesting that … But if we do none of these other things, let’s create an eradication plan before we ever plant (a non-native species).”