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Tech Tuesday

From Weed to Biofuel Source

Pennycress offers potential as source biodiesel, strategy combines biotech with pest management, and invasive weed challenge tough to battle.

The roadside weed pennycress could become a biofuel source according to USDA - Agricultural Research Service studies. ARS scientists have found that field pennycress yields impressive quantities of seeds whose oil could be used in biodiesel production.

Pennycress is in the same plant family - the Brassicaceae family - as canola, camelina and mustard. Each of those are prolific oil-rich seed producers too. At the ARS National Center for Agricultural Utilization Research in Peoria, Ill., a research team has worked to explore the potential for pennycress.

The researchers gathered oil from wild field pennycress, pretreated it with acid and used methanol (a type of alcohol) to react with the field pennycress oil to create both biodiesel and glycerol. After some added refining, the finished biodiesel was tested to determine if it met the fuel standard established by the American Society for Testing and Materials. The results suggest that with more work, problematic pennycress could become a commercial commodity.

All diesel-based oils start to gel when temperatures drop far enough. The cloud point - which is the temperature at which crystals become visible in the fuel - is a crucial factor for both biodiesel and petroleum-based diesel. Another property - pour point - is the temperature at which the fuel fails to pour due to excess solidification.

Both the cloud and pour points for field pennycress biodiesel were below the same points for soybean based biodiesel. This suggests that field pennycress biodiesel is better suited for use in cold climates than may other biodiesel fuels. And pennycress can be grown during the winter and harvested in late spring so farmers who cultivate the crop could maintain summer soybean production without a drop in crop yields.

While the biodiesel market has been hindered by the loss of the biodiesel tax credit, the need for biofuels to offset petroleum use will increase in the next few years. New sources like pennycress offer interesting options for farmers.

Two Strategies, Big Solution

Researchers at the University of Arizona are taking on a tough pest - the pink bollworm - to rid the state of a damaging cotton pest. They're making progress by planting pest-resistant cotton and then releasing large numbers of sterile moths for pink bollworm. The result is the virtual elimination of the pest from Arizona fields.

The novel control strategy is outlined in the journal Nature Biotechnology and has allowed Arizona growers to maintain high cotton yields without spraying insecticides to control pink bollworm.

The researchers say this approach results in environmental gains by using cutting-edge technology to create sustainable cotton farming practices. Pink bollworms are one of the most detrimental pests to cotton production worldwide. With the introduction of Bt cotton in 1996, farmers could cut back on spraying, but there were resistance concerns. In fact Arizona researcher Bruce Tabashnik, who headed up this new program, was the first to find a moth resistant to Bt - it was not a pink bollworm moth.

While a refuge strategy helps prevent resistance, Tabashnik says the approach is incompatible with eradication. Refuges manage pest populations, but that means accepting permanent presence of the pest. Rather than relying on refuges to thwart resistance, releasing large numbers of sterilized bollworm moths into cotton fields blocked reproduction of the wild insects instead.

This is the first time the sterile moth approach has been teamed with Bt cotton. Releasing the sterile moths into Bt cotton fields turned out to be a potent combination. Measurements taken since 2006 show pink bollworm survival is virtually zero.

In addition to promising sustained, long-term pest control without spraying insecticides for pink bollworm, the new strategy frees up acreage that otherwise would have been set aside for refuges, which can avoid yield losses. Sustainability gets a bump from biotech.

Beating Invasive Weeds is Tough

The weed-eating flea beetle has been a boon to control of infestations of non-native leafy spurge on Montana rangeland and the program has show itself effect over the course of a 9-year study. There's just one drawback: Instead of native plants flourishing in the absence of leafy spurge, other non-native species became dominant in its place.

The study, presented in the current issue of Rangeland Ecology & Management, aimed to evaluate responses of native vegetation once an invasive species was removed using classic biological control. Black and brown flea beetles have previously been used successfully as biological control agents to manage leafy spurge on a large scale.

In the current study, weed-eating flea beetles were release in 1998 on Montana land used for cattle grazing. About 6,000 beetles were introduced onto 32 plots of leafy spurge, while 20 more plots went untreated. Over time, the beetles dispersed to the untreated plots, suppressing leafy spurge there too.

By the study's end in 2006, leafy spurge foliar cover was reduced 80 to 90% compared to 1998 assessments. While other vegetation did increase once this invader was controlled, another non-native plant, Poa spp., became the dominant species. This shows that a non-native infestation makes the native plant community more susceptible to invasion by other non-native plants. New infestations need to be treated as soon as possible to reduce long-term impacts.

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