Gremmeniella abietina in Finnish Pinus sylvestris Stands in 1986-1992: a Study Based on the National Forest Inventory
Data from 24544 pine-dominated plots of the Eighth National Forest Inventory (NFI) in southern Finland were used in this study. The most commonly identified cause of damage was Gremmeniella abietina (10.6% of the stands). Disease assessments by NFI groups were reliable at the stand level. The disease was spatially clustered, being almost twice as common on peatland as on mineral soil plots. However, there was no difference between undrained peatlands and mineral soils. The more the original peatland site type had changed after drainage, the more common was the disease. On mineral soil, disease frequencies were highest on alluviated plots or on the most fertile plots. Naturally regenerated stands were affected more than artificially regenerated stands, but the difference was significant only on the richer sites. The proportion of diseased plots increased with stand density up to 25–28 m2 ha−1. Elevation of the plot had only a weak effect on damage frequency.