© 1969 by Institute of Chartered Foresters
Incidence and Importance of Peridermium pini (Pers.) Lev. in North-east Scotland
Department of Forestry, University of Aberdeen
A method of survey used to determine the distribution and intensity of disease caused by Peridermium pini (Pers.) Lev. on Pinus sylvestris L. and Pinus nigra var. maritima (Aiton) Melville is described in detail.
The results show that the disease is present in about half the stands over 30 years old. Disease intensity is low in stands under 30 years old but nearly two per cent of the trees in the age class 41–50 years old have stem lesions. The intensity declines to less than 1 per cent in age class 91–100. In stands over 100 years old, which include the remnants of the old Caledonian pinewoods the mean disease intensity is 3.66 per cent.
The disease appears to be influenced more by crop factors such as age, density, vigour and the number of years since the crop was last thinned than by site factors such as elevation, aspect, slope and proximity to the edge of the stand but the results from this survey can only indicate useful lines for further investigation.
In all, 134,200 acres (54,350 ha) of pine containing over 160 million hoppus feet (6,000,000 m3) were examined. The infected standing timber amounted to nearly two million hoppus feet (1.25 per cent of the total). The estimated annual loss of timber due to P. pini is 125,000 hoppus feet (4,500 m3) and it is shown that, due solely to age structure changes in the population, these losses will increase by a factor of at least three over the next 80 years.