sentences:  Black root rot is a disease complex on strawberry, which means that one or more organisms can infect the host.For strawberries, the common fungi are "Pythium spp"., "Fusarium spp"., and "Rhizoctonia spp"., along with several species of nematodes that function together to cause disease.Strawberries have been shown to have greater levels of rot when simultaneously exposed to both "R. fragariae" and "P. penetrans" (nematode).