The influence of pine twist rust (Melampsora pinitorqua) on growth and development of Scots pine (Pinus sylvestris)

Scots pine which had been attacked by pine twist rust during two consecutive years had an average of 38 % lower height seven years after planting than pines which were not affected by the disease. In comparison with the mildly attacked trees, the severely attacked were an average of 43 % shorter. Within the group of trees originating from a Scots pine seed orchard, the frequency of a severe pine twist rust attack was higher than within the 3 Scots pine provenances from natural stands. Of these 3 provenances, the one of northernmost origin suffered the greatest damage. Pine twist rust caused the greatest loss of height increment in Scots pine from the seed orchard, even if both attacked and unattacked trees were taller than comparable trees of Scots pine from natural stands. [ABSTRACT FROM AUTHOR]