A news release from the University of Illinois last week (March 18, 2010) announced that scientists with the Energy Biosciences Institute discovered plant-parasitic nematodes feeding on Miscanthus and switchgrass, plants being developed for use as biofuel crops. The researchers analyzed soils collected from experimental plots located in six states, including Iowa. At least two different species of plant-parasitic nematodes were reported to be found in each plot.

It is interesting and important to document the occurrence of these microscopic, plant-parasitic worms associated with new biofuel crops. But the report is no cause for alarm.

Plant-parasitic nematodes are naturally occurring organisms that inhabit almost every natural ecosystem where plants are present on Earth. It would have been surprising if plant-parasitic nematodes were not present in the soil collected from the biofuel crop research plots mentioned in the press release.

The nematodes found associated with the biofuel crops were dagger (Xiphinema), needle (Longidorus), ring (Criconema), root-lesion (Pratylenchus), stunt (Tylenchorhynchus), and spiral (Helicotylenchus) nematodes. All of these nematodes, except for the needle nematode, can feed on many different plants (including weeds) and are commonly found in fields throughout the Midwest.

Iowa State University Nematologist Don Norton studied plant-parasitic nematodes in Iowa from 1959 until 1989. Norton and his students published numerous papers in scientific journals describing plant-parasitic nematodes associated with many different natural plants, such as big bluestem, bluejoint, green bristlegrass, sedges, swamp or water smartweed and yellow foxtail to name a few, in the Kalsow Prairie in Pocahontas County, IA. Norton also published research papers on plant-parasitic nematodes feeding on corn and soybean, as well as nematodes associated with trees such as basswood, hickory, maple, oak and white pine.

The importance of plant-parasitic nematodes as pests of biofuel crops remains to be determined. Early indications from the group at Illinois suggest that nematodes are not significantly reducing yields in Midwestern fields. Further studies conducted over multiple years in various environments to compare the growth of biofuel crops to population densities of various species of plant-parasitic nematodes that naturally inhabit agricultural fields will reveal the extent to which these soil-borne pests are a concern.