Nematodes are showing up in switchgrass (pictured) and miscanthus, two of the top crops considered for biofuel production, according to the first-reported nematode survey on biofuel crops conducted by Energy Biosciences Institute (EBI) at the University of Illinois.
"Nematodes are a part of our soil systems," says lead researcher Tesfamariam Mekete, a U of I post-doctoral research associate. "However, when it comes to potential crops for biofuel production, we simply don't know which nematodes are present in these crops and at what levels."
The 2008-09 nematode survey included samples from 37 miscanthus and 48 switchgrass plots in Illinois, Georgia, Iowa, Kentucky, South Dakota and Tennessee. All sample sites had at least two nematode species reported to reduce biomass in most monocotyledon hosts. The damaging population thresholds for these nematodes to miscanthus and switchgrass are still unknown.
"The high levels of nematodes found in our survey and the damage symptoms observed in infected roots suggest parasitism may contribute to the decline of biomass production," he adds. Researchers discovered lesion (Pratylenchus), dagger (Xiphinema), needle (Longidorus), lance (Hoplolaimus), stunt (Tylenchorhynchus), spiral (Helicotylenchus) and ring (Criconema) in miscanthus and switchgrass. These nematodes have previously been reported to cause damage to switchgrass and other plant species such as corn, bent grass and turf grasses.
Needle nematodes, discovered at high levels in the sandy soils of Havana, IL, and Georgia, caused visible stunting of lateral roots and destruction of the fibrous root system. Mekete's team hopes to do further research in Havana to study the interaction between this nematode and biomass yield.
Researchers are now studying damage thresholds of lesion, root-knot and needle nematodes to miscanthus and switchgrass under greenhouse conditions. Future studies will include host suitability and population dynamics of the most prevalent nematodes associated with these perennial grasses.
In addition to discovering information on the distribution, presence, abundance and identification of these nematodes, researchers also developed species-specific DNA tests to help identify nematodes so future research can focus on developing control tactics.
"Diseases and pests have the potential to cause significant constraints on biomass production, putting the crops at risk for reductions in biomass yield and quality," Mekete says. "Of the many pests and diseases, plant-parasitic nematodes are of great economic importance because they can directly influence plant biomass and predispose plants to attack by other soil-borne pathogens."
Portions of this research have been published in GCB Bioenergy. The research was funded by EBI. The research team included Mekete, Kimberly Reynolds, Horacio Lopez-Nicora, Michael Gray and Terry Niblack of the U of I. For more information, go to www.energybiosciencesinstitute.org.