Abstract
Kentucky bluegrass (P. pratensis) may become severely damaged by Fusarium blight. When the disease occurred on a well-established plot, its dependence on the environment was studied. Factor analysis was performed to identify associations between Fusarium blight and the other variables. The disease was positively correlated with the thatch decomposition rate, negatively correlated with the plant growth variables and not correlated with any microbial group including all species, sections and composite numbers of Fusarium. Sod pH and Fusarium numbers were associated with thatch decomposition rates. Fusarium blight was least severe when the percentage of Fusarium-infected plant crowns was highest. These results are considered in relation to the possible role of phytotoxic substances that are produced during thatch decomposition and act as incitants of Fusarium blight of Kentucky bluegrass.