Submitted to: Journal of Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/9/2011
Publication Date: 9/30/2011
Publication URL: http://handle.nal.usda.gov/10113/60940
Citation: Hooks, C.R., Wang, K., Meyer, S.L., Lekveishvili, M., Hinds, J., Zobel, E., Rosario-Lebron, A., Lee-Bullock, M. 2011. Impact of no-till cover cropping of Italian ryegrass on above and below ground faunal communities inhabiting a soybean field with special emphasis on soybean cyst nematodes. Journal of Nematology. 43(3-4):172-181. Interpretive Summary: Plant-parasitic nematodes are microscopic worms that attack crop plants and result in an annual U.S crop loss of ten billion dollars. Growers need safe and effective methods for managing soybean cyst nematodes, the major economic pest of soybean plants. Italian ryegrass was therefore investigated as a cover crop for reducing the numbers of plant-parasitic nematodes in soybean fields. Two trials were conducted in Maryland to evaluate the effects of this cover crop on soybean yields and on population numbers of nematodes that attack soybean plants, beneficial nematodes and mites below the soil surface, and selected organisms, such as spiders, in the leaves. In general, soybean cyst nematode population densities were very low, and no significant differences in numbers of soybean cyst nematodes were observed between plots with or without Italian ryegrass. Planting of Italian ryegrass increased the abundance of beneficial nematodes that eat bacteria in 2009, but a reverse trend was observed in 2010, although spiders on soybean foliage were more abundant in Italian ryegrass-treated plots in both years. The results are significant because they indicate that there is no apparent benefit with respect to nematode control of growing Italian ryegrass in the untilled soybean system. This research will be used by scientists and growers who are developing sustainable methods for improving soil health and increasing crop yields.
Technical Abstract: Two field trials were conducted in Maryland to evaluate the ability of an Italian ryegrass (IR) (Lolium multiflorum) cover crop in a no-till soybean (Glycine max) planting to 1) reduce populations of plant-parasitic nematodes (i.e., the soybean cyst nematode, Heterodera glycines and lesion nematodes, Pratylenchus spp.), 2) enhance beneficial free-living nematodes and mites below the soil surface, and 3) increase beneficial arthropods in the foliage. Treatments were soybean planted into 1) an herbicide-killed IR cover crop mulch + previous year soybean stubble (referred to as IR), and 2) previous year soybean stubble (SBS) only. Italian ryegrass was planted in the fall of 2008 and 2009 and terminated at the end of spring 2009 and 2010, respectively, just prior to planting the soybean crops. Effects of herbicide killed IR on pest and beneficial organisms associated with soybean were therefore compared to no-till planting of soybean into SBS only from the previous cropping season. In general, H. glycines population densities were very low and no significant differences in population densities of H. glycines or Pratylenchus spp. were observed between IR and SBS (P > 0.05). Planting of IR increased abundance of bacterivorous nematodes (P < 0.01) in 2009. A reverse trend was observed in 2010 where SBS had higher abundance of bacterivorous nematodes and nematode richness (P < 0.05) at the end of the cover cropping period. In general, no apparent benefit of growing IR in the no-till soybean system in Maryland was observed during these two trials. Italian ryegrass did not have an impact on insect pests found in the soybean foliage and the only beneficial arthropods significantly impacted by the IR were spiders. Significantly greater populations of spiders were found on soybean foliage in IR treatments during both field trials. Potential causes of these findings are discussed.