Abstract
A hypocotyl rot disease of sugar pine is described that caused severe losses in < 3-mo.-old seedlings of P. lambertiana, Abies concolor and A. magnifica in California forest nurseries. Fusarium oxysporum was the causal organism. Greenhouse-grown seedlings developed resistance to infection by the 3rd wk after emergence, and roots were resistant at all ages. Hypocotyl rot strains were not pathogenic when tested against 14 agricultural hosts. Nine strains of F. oxysporum from agricultural hosts were not pathogenic when tested against P. lambertiana. Strains from Oregon ponderosa pine hypocotyl cankers were pathogenic on P. lambertiana hypocotyls.

This publication has 1 reference indexed in Scilit: