South African production are!3S receive insufficient winter chilling for apple production, necessitating the use of artificial means to break dormancy_ Hydrogen cyanamide (HC) alone or in combination with mineral oil (oil) is used as a rest-breaking agent in many deciduous species. The effect of different concentrations of HC and oil on budburst, yield, fruit quality and vegetative growth of mature 'Golden Delicious' apple trees were evaluated; the objective was to determine the presence of interaction between the rest-breaking effect of HC and oil when combined at varied concentrations, and to determine appropriate concentrations of HC and oil, to enhance budburst, yield and fruit quality. Three trials were conducted in the Elgin valley (34 oS, 300 m) of the Western Cape, South Africa, in 1999 and 2000. The first trial evaluated four concentrations (0, 0.5, 1 and 2%) of Dormex® (hydrogen cyanamide 520 g·L-1 ) in combination with four concentrations of mineral oil (0, 1, 2, and 4%). The second trial used three concentrations (1, 2 and 4%) of Dormex® in combination with three concentrations of mineral oil (1, 2, 4%), plus an unsprayed control, and a treatment of 6% of DNOC Winter Oil®. The third trial included five treatments: 0.5% Dormex® + 3% oil, 1 % Dormex® + 4% oil, 6% DNOC Winter Oi/®, 6% oil and a non-sprayed contro/. All of the treatments were applied at the first visible signs of bud burst. No synergistic effect was observed between oil and HC. Mineral oil at 4% plus 1 to 2% Dormex® were sufficient to break dormancy. Dormex® at 4% (2.08% HC) reduced fruit set and yield.

Cherry trees display vigorous upright growth, which tends to reduce precocity, flower bud formation and fruit quality. Three trials were performed in the 2010-2011 season on mature 'Lapins' and 'Sweetheart' sweet cherry trees in the Angol area (37°48'50"S, 72°37'36"W). The effects of prohexadione calcium (P-Ca) on shoot growth, leaf area, yield, fruit quality and flower differentiation were assessed. Two rates were evaluated (150 mg L-1 and 250 mg L-1), which were sprayed when shoots were 15 cm long and 15 days later or after harvest. The P-Ca treatment reduced the elongation of terminal shoot in both cultivars, which was due to reducing both length and number of internodes, resulting in a reduction in total leaf area. This led to better light penetration and distribution in tree canopies. Applications of P-Ca to shoots 13 to 15 cm in length controlled shoot growth adequately, while the effect was excessive when the spray was repeated after 15 days. No additional effect was detected when the second application was applied after harvest. P-Ca treatments increased the number and size of reproductive buds and the number of floral primordia per bud. The development of floral structures in the buds was more advanced compared to the control. Regarding fruit quality, soluble solids concentration and fruit size there were no significant effect from P-Ca application, while the fruit firmness increased. One single application of P-Ca at 250 mg L-1 in spring appears to be the most effective treatment to control vegetative growth, to increase the number of flower buds and to improve fruit firmness.

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A study was carried out to evaluate the effect of rain protective covers on the vegetative and reproductive development and fruit quality of sweet cherry trees. The trial was conducted in the 2010-2011 season in a commercial orchard in Collipulli, Chile, with gabled (Vöen ®) crop covers on 10 rows. In half of each row, trees were protected with rain covers from bud-burst, and the other half was protected from first red colour development of the fruit onwards; a treatment without protective rain cover served as control. The following variables were assessed: temperature, relative humidity, rainfall, phenology, intercepted photosynthetically active radiation (IPAR), fruit development, foliar area, flower bud differentiation, fruit set, vegetative growth and fruit quality at harvest and after conventional cold storage were measured. The protective covering filtered approximately 40% of incident PAR. Crop cover at budburst advanced tree phenology and increased shoot length. Fruits of cherry trees protected during the colour development phase showed less colour. Protective covering installed at bud-burst increased fruit size, weight and soluble solids concentration, but with more cracking at the style-end scar of the fruit and with reduced fruit firmness. Flower bud differentiation was advanced by both treatments.

No abstract