FURTHER OBSERVATIONS OF TWO SPUR-TYPE APPLE CULTIVARS IN HIGH DENSITY PLANTING SYSTEMS

Two cultivars Goldspur and Starkrimson grafted on rootstock MM 106 were planted in 1974 in single-row, double-row and three-row systems. The distances with Goldspur were: 3.8 x 1.0, 3.8 + 1.3 x 1.5 and 3.8 + 1.3 + 1.3 x 1.5 whereas with Starkrimson they were 3.8 x 1.3, 3.8 + 1.5 x 1.5 and 3.8 + 1.3 + 1.3 x 1.5. Average yields in t. per hectare for 3 years of full bearing, from the 4th to the 6th year of age, were with Goldspur: 60.6 (single-row), 58.6 (double-row), 58.8 (three-row) and 41.8 (single-row), 44.1 (double-row), 40.3 (three-row) with Starkrimson. In the last two years the yields in the three-row system decreased markedly. The bearing efficiency assessed as yield per tree in kg/cm2 of trunk cross section area for full bearing (second to sixth year) averaged for all systems was 2 636 kg with Goldspur and 1 233 kg with Starkrimson. Starkrimson gave more vigorous trees (trunk diameter R = 73.4 mm) than Goldspur (R = 60.6 mm). The yield of single trees varied considerably from tree to tree in each year and when it was more than 20 kg per tree led to alternate bearing. Fruit quality was satisfactory for both cultivars except in the three-row system with Starkrimson as the fruits were not coloured enough in the middle row.

It is suggested that Starkrimson on this rootstock is suitable only for single-row systems, but this cannot yet be said to be the case for Goldspur.