2007 Annual Report 1a.Objectives (from AD-416) Broaden soybean germplasm base for genetic resistance to new and emerging nematode populations and integrate cultural practices to augment sustainability to host plant resistance for soybean cyst nematode. 1b.Approach (from AD-416) In the U.S. publicly available soybean cultivars trace their nematode resistance to Peking, PI 88788 and/or PI 437654. Nematodes have adapted to both Peking and PI 88788. New poplations with virulence on PI 437654 (cv. Hartwig) have been found. PI lines 567516C and 437655, are resistant to most virulent nematodes. Other unique sources of resistance have been identified in soybean. Characterize new sources of resistence to identify and broaden the number of resistance genes for nematodes. Use marker assisted selection for gene pyramiding and increased breeding efficiency. Develop germplasm with new genes. Determine influence of resistant germplasm and non-host crops on nematode variability. Determine dynamics of nematode egg population density in field plots. Manage nematode populations through reduced tillage practices, early maturity soybeans, manipulation of pH and cover/trap crop. 3.Progress Report This report serves to document research under a Reimbursable Agreement between ARS and the Iowa State University. Additional details of research can be found in the report for the in-house project 6402-21220-008-00D, "Genetic and Cultural Methods to Manage Cyst Nematode in Soybean." SCN resistance is one of the most important needs in soybean production to avoid yield losses by the feeding of the nematode on susceptible cultivars. Breeding SCN-resistance into soybean cultivars is the primary method for controlling SCN and reducing yield losses. Recent work identified 118 exotic soybean plant introductions resistant to nematode populations. One of these sources is PI438489B, which is genetically different from most commonly used sources and has resistance to multiple nematode populations. Crosses were made with high yielding susceptible cultivars to PI438489B and segregating populations are being advanced for further evaluations for nematode resistance.