Registration of 'Summit,' a High-Yielding Soybean with Race-Specific Resistance to Phytophthora sojae

Phytophthora sojae Kauffmann and Gerdemann, the causal agent of Phytophthora root and stem rot, may result in severe losses in soybean fields planted with susceptible cultivars. However, the disease can be successfully managed through the use of cultivars with genetic resistance. 'Summit' soybean [Glycine max (L.) Merr.] (Reg. No. CV-508, PI 665057) was developed by the Ohio Agricultural Research and Development Center of Ohio State University and was released in 2010. The cultivar was bred with the objective to develop a high-yielding maturity group (MG) II cultivar with resistance to P. sojae. Summit was developed through early-generation testing with yield-based selections of F-2-derived heterogenous lines and F-4 lines and originates from a single F-4 plant selection of a cross between 'IA3023' and breeding line HS99-4045. Summit was evaluated in 30 environments from 2006 to 2011. In the Ohio Preliminary and Advanced Line Tests, Summit had a significantly higher yield than check cultivars, with seed yield 106% of 'Wyandot' and 110% of 'OHS 202'. In the Northern Region Preliminary Test, Summit had a similar yield as the MG III check cultivar 'IA3024' and a significantly higher yield than the MG II check cultivar 'IA2068' (109%). Summit possesses Rps1k and Rps3a alleles for race-specific resistance to P. sojae. As a high-yielding, conventional, mid-MG II cultivar with resistance to P. sojae, Summit is a good choice for producers of non-genetically modified soybeans in Ohio and other regions with disease pressure from P. sojae..