Effect of Host Resistance to Fusarium virguliforme and Heterodera glycines on Sudden Death Syndrome Disease Severity and Soybean Yield

Abstract

Fusarium virguliforme, the soilborne fungus that causes sudden death syndrome (SDS), and Heterodera glycines, the soybean cyst nematode (SCN), are economically important pathogens that often occur concomitantly in Kansas soybean fields. To examine F. virguliforme and H. glycines interactions across multiple environments, four soybean genotypes with different levels of resistance to SDS and SCN were planted at three to four locations in northeastern Kansas in 2008 and 2009. Pathogen population densities were quantified at planting (Pi), midseason (Pm), and harvest (Pf). At harvest, SDS AUDPC, F. virguliforme root population densities, H. glycines reproductive factors (RF), and yield were determined. The performance of resistant (R) genotypes varied with environment and disease pressure, but SDS-R genotypes were associated with 36% greater yields than SDS-susceptible (S) genotypes in high SDS environments. Even moderate levels of SCN resistance reduced SDS disease severity in SDS-S genotypes. Negative correlations (P ≤ 0.05) were observed between yield and AUDPC, and yield and F. virguliforme root population densities. A regression model that combined both of these covariates explained 57% of the yield variation. Disease severity was positively correlated with H. glycines Pi, but negatively correlated with RF. The data emphasize the importance of combining SDS and SCN host resistance in fields with a history of both diseases. Accepted for publication 6 November 2013. Published 27 January 2014.