Fall soil sampling for SCN may reveal that the nematode was responsible for disappointingly low soybean yields in 2012, although it may be difficult to separate this from low yields due to drought conditions and other diseases and insect pests.
Fall soil sampling for SCN in fields in which soybeans will be produced in 2013 will reveal if SCN-resistant soybean varieties should be grown. If SCN has not been discovered in a field before, areas where the nematode can be first found in soil samples include near field entryways, in low spots and in high pH areas (see Figure1).
Prolonged use of SCN-resistant soybean varieties with the common PI 88788 source of resistance can lead to unintentional build-up of SCN population densities in the soil, increasing the amount of damage caused by the nematode in future years. It is a good idea to determine the SCN population density in fields where SCN-resistant soybean varieties with the common, PI 88788 source of resistance have been grown for numerous years. In this case, soil sampling for SCN every six to eight years is adequate, depending on how frequently soybeans are grown (sample after every three or four soybean crops).
Collect a good sample
More information on SCN
For more information about the biology and management of SCN, visit www.soybeancyst.infoand www.planthealth.info/scn_basics.htm. Also, copies of the new, 2nd edition of the Soybean Cyst Nematode Field guide are now available for no charge by calling the Iowa Soybean Association at 800-383-1423 or by contacting an ISU Extension field agronomist.