Distribution of SCN in Iowa and occurrence of HG types

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Investigator: Gregory L. Tylka, David Soh
Funding: Iowa Soybean Association

SCN was first discovered in Iowa in Winnebago County, in extreme north central Iowa, in 1978. Currently, the nematode is known to exist in 97 of 99 Iowa counties (all except Allamakee and Ida Counties). A random survey of Iowa was conducted in 1995-1996 to better define the distribution of SCN in the state. SCN was found in 74% of Iowa fields sampled in that survey. SCN was found much less frequently in no-till fields than in tilled fields sampled in the survey.

From 2007 to 2009, the random survey of Iowa for SCN is being repeated. In addition to assessing the distribution of SCN in Iowa 12 years after the last survey and determining the effects of tillage on SCN populations currently, the SCN populations obtained in the 2007-2009 survey will be tested to determine the HG type of the nematodes. The HG type of an SCN population indicates how well it reproduces on the sources of SCN resistance used in SCN-resistant soybean varieties.

Preliminary key findings from the work are:

  • Of the 205 fields sampled in 2007, 71% were infested with the nematode.
  • SCN infestations were found in the same percentage of no-till and tilled fields sampled in 2007.

This research will continue through 2010.

SCN has been found in the 97 counties (those colored in red).SCN was discovered in 74% of 399 randomly selected fields sampled in 1995-1996.

SCN was discovered in 71% of 205 randomly selected fields sampled in 2007. 	  	Click on the image to view a one-page information sheet (mini poster) in pdf format 	Click on the image to view a one-page information sheet (mini poster) in pdf format