Mineral oil and dinitro-orthocresol in breaking the dormancy of apple trees

Abstract

The experiment was undertaken in Fraiburgo in 1973 using five - year - old plants and repeated for four consecutive years on apple cv. Golden Delicious/MI-793. Different combinations of mineral oil and DNOC concentrations were applied in an only annual spray at bud-swell stage. The studied parameters were flowering and bloom periods, percentage of lateral and terminal bud-break, number of flower cluster, "fruit set", total number of fruits before and after thinning, fruit production and average weight. The treatments with mineral oil + dinitro-orthocresol (DNOC) advanced leaf and flower bud-break. The same treatments increased the percentage of lateral and terminal bud-break, number of flower cluster and production as a result of an increase of concentration of mineral oil and DNOC until 0,2%. Increased bud-break caused higher number of spurs and enhanced production for the subsequent years. Mineral oil and DNOC negatively influenced the fruit set and average fruit weight was not affected.