REPORT ON THE INTERNATIONAL PLANTING SYSTEM TRIAL IN POLAND

Apple trees grafted on M.9 and M.27 rootstocks, and on Antonovka seedlings with B.9 interstems, planted on various systems and at densities from 2051 to 8889 per ha, produced the highest yield per hectare at the highest densities. The yield per tree was positively correlated with tree vigour. Tree growth was slower and the crop was much smaller than at the other European sites. During six years of the trial there were four hard winters with temperatures approaching or below -30°. The winter frost of 1980–81 damaged trees and dwarf rootstocks, the winter frost of 1984–85 killed fruit buds, and the winter frost of 1986–87 killed Golden Delicious trees and damaged Gloster trees.