Phytophthora sansomeana , an Emerging Threat to Soybean Production.

In 1990, new Phytophthora strains, later recognized as a new species, Phytophthora sansomeana, were found to cause Phytophthora root rot (PRR) in soybean in addition to P. sojae. The emergence and spread of a second pathogen causing PRR poses a significant threat to soybean production. While genetic resistance to P. sojae has been developed and widely deployed as a management tool, these varieties appear largely ineffective at controlling P. sansomeana, which has a broad host-range and can infect and survive on non-leguminous hosts including fir trees, Rosaceous fruit trees, maize, and several herbaceous weeds. This contributes potential for broad distributions worldwide across both agricultural and natural ecosystems. Despite having been studied since the 1980s under a variety of informal designations, little is known about the epidemiology, host-interactions, and management of this emergent pathogen. Due to the lack of management options, increased frequency of first reports in new geographic areas, and the overall limited body of knowledge surrounding this novel pathogen, P. sansomeana warrants more research attention from both biological and disease management perspectives. The aim of this review is to summarize the hosts, distribution, pathogenicity, and current management strategies of P. sansomeana and to provide a concise record of where it has been studied under other informal designations. Its role in PRR of soybean is emphasized due to the economic magnitude of PRR-associated losses and its well-documented aggressiveness as a soybean pathogen. [ABSTRACT FROM AUTHOR]