FOUR NATURAL SPUR-TYPE MUTANTS OF McINTOSH APPLE

Abstract

The size of trees and the degree of spurriness of four spontaneous mutants of McIntosh apple (Malus pumila Mill.) were evaluated in 3- and 4-yr-old orchard trees in 1971 and 1972. The trunk-cross-sectional area was 13% smaller in MacSpur than in standard McIntosh. The number of fruiting spurs, either per 2-yr-old branch or in relation to the number of vegetative shoots, was used as a measure of spurriness. The degree of spurriness was very high in Morspur and MacSpur, high in Dewar, and moderate in Starkspur and standard McIntosh.