challenging for storage operators. At low temperatures around 33 °F, the cultivar can develop symptoms of chilling injury (CI) such as soft scald and soggy breakdown, whereas at a higher temperature of 38 °F the fruit can be susceptible to bitter pit
Yosef Al Shoffe and Christopher B. Watkins
Denise Neilsen, Gerry Neilsen, Sunghee Guak, and Tom Forge
end point with data expressed as g/100 mL malic acid equivalents. An additional random subsample of 10 fruit at harvest was used to calculate incidence of disorders including water core, sunburn, internal breakdown, and bitter pit. Analysis of variance
J. Thomas Raese and S. R. Drake
Sprays of calcium materials were applied at high volume rates (620 g Ca/400 liters) with a handgun during early June, late June, and mid-July versus mid-July, early August, and late August for five years, 1985 to 1989. Leaf injury was most severe for the late sprays but no spray injury was observed on the fruit surfaces. Bitter pit was markedly reduced with all sprays except CaSO4. In some years, bitter pit was controlled better with the early sprays. Either early or late sprays improved fruit quality including overall appearance, reduced scald development, improved red color of the skin, increased fruit firmness and reduced incidence of bitter pit in cold air (0°C) storage. Soluble solids and acidity in the fruit was not affected by calcium sprays. Leaf Ca was higher from the late spray applications than from the earlier applications. All calcium chloride spray materials resulted in increased fruit peel and cortex Ca. Calcium nitrate sprays tended to increase fruit nitrogen concentrations leading to undesirable higher N:Ca ratios in the fruit.
T. Auxt Baugher, H.W. Hogmire, A.R. Biggs, S.I. Walter, D.W. Leach, T. Winfield, and G.W. Lightner
Apple packout audits were conducted during 1991 to 1993 to assess effects of five orchard systems (three cultivars, two age groups) on fruit packout and determine if relationships exist between light quality and productivity. Cultivar/rootstock combinations on 1979 T-trellis and central-leader systems had the lowest light levels and relative yields. Trees on either 1979 3-wire trellis, 1986 MIA, or 1985 West Virginia spindle had the highest light transmission, and trees on 1979 or 1985 West Virginia spindle systems had the highest yields. Extra fancy/fancy packouts across systems ranged from 40% to 85%. `Empire', regardless of system, had the highest packouts, and `Golden Delicious' on 1979 or 1986 central leader had the lowest packouts. A regression analysis comparing percentage packout in grades below fancy to percentage full sun indicated that reduced packouts were related to low light conditions. Orchard system influenced the number of fruit downgraded due to color, russet, bruises, bitter pit, cork spot, apple scab, rots, sooty blotch/fly speck, and tufted apple budmoth. Regression analyses comparing defects to field data indicated that bitter pit decreased as yield efficiency increased, and rot and sooty blotch/fly speck incidence were related to low canopy light penetration. Revenue losses were disproportionate to percentage of downgraded fruit because some defects had a greater impact on grade than others. The greatest revenue losses were for russet in `Golden Delicious' on 1986 central leader ($1656.60/acre) and for bitter pit in `Golden Delicious' on 1979 T-trellis ($1067.30/acre). Total losses in returns for individual systems ranged from $453.71/acre for `Empire' on 3-wire trellis to $3145.49/acre for `Golden Delicious' on 1986 central leader. The comparisons of young versus mature system yields and packouts indicate that medium- to high-density vertical or inclined canopy systems are superior to horizontal or low-density vertical freestanding systems. The cost-benefit analyses prescribe areas where management can be changed in existing systems to increase profitability.
Jayson K. Harper and George M. Greene II
This study quantifies the discounts and premiums associated with various quality factors for processing apples (Malus domestica Borkh.). Discounts and premiums were estimated using a hedonic price model and quality data from a total of 137 samples representing three processing apple cultivars (45 `York Imperial', 43 `Rome Beauty', and 49 `Golden Delicious'). Price discounts in the sample were statistically significant for fruit size, bruising, bitter pit, decay, misshapen apples, and internal breakdown. Commonly cited defects, such as insect damage and apple scab, did not cause significant price discounts.
`Newtown' apples (Malus domestics Borkh.) treated weekly with urea at 10 g·liter-l or Ca(NO3)2 at 7.5 g·liter-1 for 5 consecutive weeks from late August were greener at harvest and during storage than comparable control fruit. A postharvest dip in Nutri-Save, a polymeric coating, was better for retention of skin greenness than a dip in diphenylamine and both gave greener apples than control (nondipped) fruit. Fruit treated with Ca(NO3)2 displayed lesions that were larger and more numerous than typical bitter pit in the control fruit.
William D. Wolk, O.L. Lau, G.H. Neilsen, and Brian G. Drought
A study was undertaken to identify key factors associated with storage disorders in three commercially important apple cultivars in British Columbia and to determine how early in the season associations could be measured. Fruit mass, density, and concentrations of N, P, K, Ca, Mg, and dry matter were determined for `McIntosh', `Spartan', and `Golden Delicious' apples (Malus ×domestica Borkh) from ≈30 commercial orchards 9, 6, 3, and 0 weeks before harvest. Storage samples were collected at commercial harvest and evaluated for the development of internal breakdown (`McIntosh' and `Spartan') or bitter pit (`Golden Delicious') after 4 and 6 months of 0 °C air storage. Mass and [Ca] and the mass/[Ca] and [K]/[Ca] ratios were the factors most often significantly correlated with storage disorders within each year for all three cultivars. Correlations were as frequently significant 6 and 3 weeks before harvest as they were at harvest. Mass of `McIntosh' and `Spartan' was the only variable consistently related with breakdown in all 3 years of the study. There were no variables with a consistent relationship to bitter pit in `Golden Delicious'. Fruit [Ca] was associated with the relative levels of disorders within years but could not be associated with specific levels of disorders across all years.
Renae E. Moran
In 2004, prestorage delays and CA storage were compared for occurrence of disorders. Fruit were harvested at a starch index of 5.9. Fruit were exposed to either a 2- or 5-day prestorage delay at 17 °C; or placed immediately into cold storage (control) at 0.5 °C. An additional treatment was CA storage at 2.5 °C. In February, occurrence of soft scald, soggy breakdown, and bitter pit were measured on 40 fruit per replication. Fruit were from `Honeycrisp'/M.26 trees planted in 1994. Treatments were replicated five times with four trees in each replication. Soft scald was very severe in this year, with 84% of control fruit being affected. Two-day prestorage delay reduced it to 48% and 5-day delay to 21%. Soggy breakdown was also severe with 14% of the fruit being affected. Two- and 5-day delays had no effect on occurrence of soggy breakdown, but CA storage increased it to 65%. Bitter pit was very rare and not affected by any of the treatments. These results demonstrate that in severe cases, shorter prestorage delay is not effective in preventing soft scald or soggy breakdown.
Laura J. Lehman and George M. Greene II
A two year study of `Golden Delicious' and `York Imperial' apple responses to delayed cooling and CA storage imposition after harvest was completed in 1991. Apples from six to eight commercial orchards were harvested at an acceptable maturity level for long-term storage, subjected to a delay in refrigeration (0,3, or 6 days) followed by a delay in CA storage imposition (0,14, or 28 days), and then stored at 0°c, 2.4% oxygen, and 1.6% carbon dioxide for up to eight months. Fruit acidity, soluble solids content, bitter pit incidence, scald, internal breakdown, and the development of low oxygen injury were not influenced by the delays. Delays often resulted in more rot and excessive weight loss during storage. Delays in both cooling and CA storage imposition had an additive effect on fruit softening, such that the longest delays resulted in the softest fruit.
Frank J. Peryea, Denise Neilsen, and Gerry Neilsen
The recommendations for boron (B) sprays in deciduous tree fruit orchards have changed little over the past 50 years. We conducted two 3-year field studies evaluating the effect of two modifications to the existing recommendation for B maintenance sprays on apple (Malus ×domestica) tree nutritional status. A widely recommended Na polyborate-based commercial B spray product was used as the B source. Postbloom sprays of B applied at the recommended annual B maintenance rate of 0.56 kg·ha-1 to `Scarlet Gala' apple trees consistently increased fruit B concentration but had a weaker effect on leaf B concentration in early August, the recommended timing for sampling leaves for mineral element analysis. Applying half or all of the annual B maintenance rate in a spray at the pink flowering stage increased flower cluster and early-season leaf B concentrations as well as having positive effects on fruit and leaf B concentrations. The pink sprays increased flower cluster Na concentration but had no effect on leaf and fruit Na concentrations. In the second study, one-quarter of the annual B fertilizer requirement was tank-mixed with each of four biweekly CaCl2 sprays applied starting in early June for bitter pit control. This treatment consistently increased `Scarlet Gala' fruit B concentration but had a lesser effect on August leaf B concentration. It did not interfere with fruit Ca status, and increased both fruit and leaf Na concentrations. Leaf Na concentration in all treatments was substantially lower than levels associated with specific Na toxicity of deciduous fruit trees. The results of these experiments indicate that applying B sprays at the pink flowering stage timing and tank-mixing B with CaCl2 sprays applied for bitter pit control are useful practices to enhance B spray efficacy and convenience of application.