Tufts of grayish to pale-colored sporangiophores on the underside of leaves easily distinguish the infection from other foliar diseases.

[2] Peronospora manshurica commonly begins its disease cycle in the spring, with overwintering oospores mainly serving as the primary inoculum.

[4] This oospore will function as a survival structure for the pathogen over the winter, and serve as the primary inoculum the following spring.

Peronospora manshurica is biotrophic, meaning that a living host (most commonly the soybean) is required in order for the fungus to survive.

[7] In order to initiate infection of its host, the pathogenic conidial spores are dispersed by wind, rain-splash, and run-off.

This predominantly occurs when seeds and surrounding soil contain oospores, causing seedling hypocotyls to be infected upon germination.

[7] Historically, this pathogen has been rather low risk, because infected crops do not typically exhibit significant yield loss.

[7] Despite this, yields are still not impacted significantly enough by P. manshurica to warrant fungicide treatment in the United States.

[7] With the pathogens extensive prevalence, the emergence of a particularly destructive race could be detrimental to a susceptible host population under favorable conditions.