Rotation Crop Evaluation for Management of the Soybean Cyst Nematode in Minnesota

Crop rotation is an effective tactic for soybean cyst nematode (SCN) management. In the North Central region of the USA, corn is almost exclusively used as a nonhost rotation crop with soybean. This study was conducted to determine the effectiveness of crops common to or having potential use in the North Central region as rotation crops for managing SCN. Sixteen potential rotation crops and SCN-resistant and susceptible soybeans were grown along with six fallow controls in three commercial field sites near Waseca, Lamberton, and Morris, MN, in 2001, and SCN-susceptible soybean was grown on all plots in 2002. Nematode populations at planting, midseason, and harvest were measured both years; soybean yield was measured in 2002. There was large variability in SCN populations and soybean yields at the three sites. Nevertheless, significant treatment effects were detected at all sites. While all of the rotation crops lowered SCN populations compared with SCN-susceptible soybean, there were only subtle differences among the individual rotation crops and among different groups of the crops. Leguminous nonhosts or poor hosts were best in reducing SCN population density. Corn, the most common rotation crop in Minnesota, was among the least effective in reducing nematode populations. There was an undetectable yield benefit from SCN management, although differences in yield were observed among the rotation crop treatments—probably due to agronomic factors. The data suggest that a single year of rotation of soybean with any of these crops before planting a susceptible soybean may not be sufficient in