Charles G. Embree

The influence of crop-load, delayed cooling and storage atmosphere on post-storage quality of 'Honeycrisp'™ apples

Summary The influence of crop-load, delayed cooling and storage environment on fruit quality and disorder, and on the incidence of rot was investigated on 7 year-old ‘Honeycrisp’ apple (Malus domestica Borkh.) trees on ‘Malling 26’ rootstocks at three different sites during 2003 and 2004. Fruit from non-thinned (control) trees, or trees thinned to three, six or nine fruit cm–2 trunk cross-sectional area (TCSA) were harvested and: (1) immediately cooled over 24 h to 3°C [commercial (Comm)] then stored at 3°C in refrigerated air (RA) or in a controlled atmosphere (CA; 2.5 kPa O2, 1.0 – 1.5 kPa CO2); or (2) held at 20°C for 6 d, followed by 1 d at 3°C [= 7 d pre-storage warming treatment = delayed cooling (DC)] then stored at 3°C under RA or in CA storage. After 3 and 6 months of storage, fruit mass (g), firmness (N), colour (% red), soluble solids content (SSC; %), titratable acidity (TA; mg malic acid equivalents 100 ml–1 juice), “greasiness” (0–3 scale), the extent of disorders such as soft scald (%) and low temperature breakdown (LTB; %), as well as the incidence of rot (%) were assessed. In general, as crop-load increased fruit mass, firmness, colour, SSC and TA decreased regardless of the effects of DC and storage treatment. Crop-load did not influence fruit “greasiness” and had an inconsistent and less-pronounced effect on soft scald, LTB and rot. The 7 d pre-storage warming treatment reduced the incidence of soft scald and LTB, irrespective of crop-load, but had little influence on other fruit quality measurements. Although the storage environment did not consistently alter quality, CA-stored ‘Honeycrisp’ apples tended to be more acidic, less “greasy” and develop less soft scald. Overall, the data indicate that the highest fruit quality was attained by thinning ‘Honeycrisp’ trees as close to three fruit cm–2 TCSA as possible, by subjecting newly-harvested fruit to a 7 d pre-storage warming period of 20°C, followed by CA storage at 2.5 kPa O2, 1 – 1.5 kPa CO2 at 3°C.

Performance of prohexadione-calcium on shoot growth and fruit quality of apple -Effect of spray surfactants

Vegetative growth control of apples (Malus × domestica Borkh.) is necessary to maintain a balance between growth and cropping. Pruning is a labour-intensive management practice to achieve this and intrinsically stimulates new growth. Prohexadione-calcium (PC) is a plant bio-regulator that effectively regulat es the shoot extension growth of apples and other tree fruits. Previous research has demonstrated that its efficacy can vary based on the use of spray surfactants and adjuvants. This study investigated the efficacy of two rates of Apogee™, the commercial form of PC, used in combination with the spray surfactants Sylgard 309 and LI 700, on extension shoot growth and yield parameters. Experiments were conducted in Ontario on Empire and Nova Scotia on Royal Court™ Cortland apples. Treatments of 0, 75 or 125 mg L-1 PC, with and without either 0.5% (vol/vol.) LI 700 surfactant or 0.05% (vol/vol) Sylgard 309 surfactant were applied to Empire trees, and 75 or 125 mg L-1 PC, with or without 0.5% (vol/vol) LI ...

Fruit mass, colour and yield of ‘Honeycrisp’™ apples are influenced by manually-adjusted fruit population and tree form

Summary The influence of three manually-adjusted crop loads [3, 6 and 9 fruit cm–2 trunk cross-sectional area (TCSA)] on ‘Honeycrisp’™ apple (Malus domestica Borkh) quality and canopy volume were compared with unadjusted control trees. The crop-load treatments were applied at three sites over two consecutive seasons at 50 days after full bloom (DAFB). Sixteen trees at each site were selected annually, with the treatments being applied in a randomisedcomplete-block design. Fruit mass and fruit colour (%) were used to assess quality at harvest, while yield was determined by the mass (kg) of fruit cm–2 TCSA. The canopy volume (CV) for each tree was calculated following harvest and used as a covariate in determining its influence on fruit size and colour. As crop load decreased, harvested fruit mass and % red colour increased. For similar crop-load adjustments, larger tree CVs (in m3) resulted in greater fruit mass. Crop load and fruit-canopy density (fruit m–3 CV) were more highly correlated with fruit mass than with % fruit colour. The highest fruit quality occurred at the three and six fruit cm–2 TCSA. In addition, manually adjusting the crop-load at 50 DAFB did not eliminate the disposition of ‘Honeycrisp’™ towards biennial bearing in Nova Scotia’s climate.

Certain chemical thinning treatments advance maturity of Paulared apple

Mature Paulared (Malus ×domestica Borkh L.)/MM106 apple trees with a heavy bloom were sprayed with carbaryl [Sevin® XLR 1.25 mL L–1 (600 mg L–1 a.i.)], benzyladenine (BA)/gibberellic acids (GA4 + 7) [Accel® 1.22 mL L–1 (23.1 mg L–1/2.31 mg L–1 a.i.)], carbaryl [Sevin® XLR 1.25 mL L–1 (600 mg L–1 a.i.)] + BA/GA4 + 7 [Accel® 1.22 mL L–1 (15.6 mg L–1/1.56 mg L–1 a.i.)] and napthaleneacetic acid (NAA) [FruitoneN® 0.32 g·L–1 (1.13 mg L–1 a.i.)] when fruitlet diameter was 7 mm. Ethephon [Ethrel® 2.29 mL L–1 (549.6 mg L–1 a.i.)] was applied at the 13.5 mm fruitlet diameter stage. Carbaryl alone, NAA and ethephon all resulted in improved fruit size at harvest, whereas BA/GA4 + 7 was ineffective as a thinner and did not alter fruit size at harvest. Of these treatments, only ethephon significantly reduced crop load. Both NAA and ethephon, and especially ethephon, advanced fruit maturity at harvest as indicated by a lower Streif index. Only ethephon increased commercial levels of fruit colour and following-year blos...