Conditions conducive to an epidemic of Gremmeniella abietina, European race, in red pine plantations

Abstract

In North America, Gremmeniella abietina, European race (GaEU), was reported in 1975. Our objective was to follow the spread of GaEU on red pines growing on flat land and on slope. Annual height infection varied significantly on flat land, ranging from 60 to 110 cm in 1991 to 0 to 50 cm in 1992. On the slope, pines in the bottom were killed by the disease, but survived on the top. Favorable conditions follow a horizontal line about 10 m over the lower elevation and are probably related to fog or mist. The horizontal disease spread over a 3-year period was only 20 m and this is mainly explained by the absence of ascospores in North America.