Talven tuhot hedelmäpuissa ja marjapensaissa vuonna 1947

Authors

• H. J. E. Hårdh Maatalouskoelaitoksen kasvitautiosasto, Tikkurila

DOI: https://doi.org/10.23986/afsci.71250

Abstract

Lately there have been injurious winters for the cultivation of fruit in Finland in 1915—1917, 1927—1929 and 1939—1942. The winter 1946—1947 again damaged fruit trees and the berry-bushes gooseberry, currant and raspberry; this damage was most severe in the best areas for cultivation of fruit in Varsinais-Suomi (Ab) and Satakunta (St). In these areas about 10—75 % of the fruit trees and 75—80 % of the berry-bushes were injured or died. Slight injuries generally have been noted in Uusimaa (N), Häme (Ta), in the Valley of Kokemakiriver (St) and in the neighbourhood of Tampere (Ta). In southern Pohjanmaa (Oa) fruit trees and berry-bushes have been injured, too. The limit of the general injury-area is drawn through Vaasa (Oa), Alavus (Oa) and Virolahti (Ka). This limit closely follows the contour-line, to the west and southwest of which the depht of snow on March 15th was 30 cm or less (fig. 2). In the injury-area mentioned damage was such that the leaves expanded slowly in the spring, the flower buds, that appeared abundantly, opened slowly and the leaves and fruit were smaller than normally. In severely damaged trees the flower buds did not open, but dried up (fig. 1). In damaged trees, the cambium was generally brownish, the wood drier than normally, the roots, however, were generally white within and vigorous. The leaves of the berry-bushes expanded slowly in the spring; later in summer a many of the branches of damaged bushes died. These bushes generally grew new branches from their root. The damage to fruit trees and berry-bushes was due to the drying of the parts above ground in the spring, when the warm and sunny weathers induced activity of the vital functions in the plants. The soil was, however, deeply frozen because of the thin winter snowcover and when the thaw waters and rainwaters in May, with a little amount of rain, did not melt the ice, the roots were still in June in the frozen soil and did not absorb enough water from the soil, which even apart from this was too dry, to make up the evaporated moisture. Then the soft surface parts of the trees, rind and buds, were damaged. In summer the roots may perhaps have absorbed a normal amount of water, but because of the damage to the vascular system in the rind the flowing of solutions in the summer was not normal, and the shoots, leaves and fruits grew weakly. The damage to fruit trees was neither due to properties the variety and stock nor the age of trees (6). In the central parts of the country twigs of trees and sapling fruit trees were frozen because of the severe frost in winter. It can be estimated that 20—25 % of the fruit yield in Finland in 1947 was lost for the winter injuries.