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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.

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M. Meheriuk

`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.

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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.

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W. J. Bramlage, M. Drake, and J. H. Baker

Abstract

Postclimacteric respiration of apples (Malus pumila Mill. cv. Baldwin) decreased as peel Ca level increased from 400 to 1300 ppm. The respiratory climacteric occurred simultaneously in fruit of all Ca levels, indicating that maturation was unaffected by these Ca levels. Occurrence of bitter pit was inversely related to Ca levels. Scald, internal breakdown, and decay were more prevalent when peel Ca was below 700 ppm. Fruits were firmer after 5 months storage in 0°C air if Ca was below 700 ppm, although they were larger, yellower, and more susceptible to decay and other disorders than higher Ca fruit.

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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.

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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.

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C. R. Unrath

Abstract

Irrigation and evaporative cooling of ‘Red Delicious’ apple trees over 2 growing seasons resulted in a reduction in environmental stress as evidenced by plant and air temp reductions (8). The trees were spot-picked weekly, based on acceptable color to meet grade standards. Harvesting was completed one week earlier on trees receiving overtree sprinkler irrigation as compared to those with undertree or no irrigation. Fruit from trees which received overtree irrigation had greater surface coloration and nearly twice as much surface area with good solid red color as fruit which received undertree or no irrigation. Overtree irrigation improved fruit size and shape during 1969 but not 1970; increased soluble solids, and reduced cork spot and bitter pit in 1970. Lower firmness of overtree irrigated apples in 1969 was attributed to their greater size. Irrigation (over and undertree) had no influence upon internal breakdown measured after 4 months of storage at 32°F.

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Stephen S. Miller

Abstract

Growth of ‘Topred Delicious’ (Malus domestica Borkh)/Malling Merton (MM) 111 apple trees during the first 5 years in the orchard was significantly affected by the orchard floor management system. Trees grown in a mowed sod were smaller and had a significantly lower yield efficiency (kg/cm2) than those grown under cultivation or a herbicide strip system. N source or rate did not influence growth or average yield/tree; fruit size and bitter pit development were significantly greater where a complete fertilizer (10N-4P-8K) was applied. N increased tree growth under sod but not under a cultivated or herbicide strip managment system. Growth response in the first year was increased when larger-sized trees were planted under a weed-free management system and trees were headed to 76 cm.

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William J. Lord, John H. Baker, and Richard A. Damon Jr.

Abstract

Incorporating high Ca lime with the soil in the planting hole for trees of ‘Sturdeespur Delicious’ apple (Malus domestica Borkh.) on Malling-Merton 106 rootstock increased leaf Ca for the first 2 years. Annual soil applications of NH4NO3 for 8 years, in comparison to applications of KNO3or Ca (NO3)2, increased acidity of soil to depths of 50 to 61 cm. Soil Ca levels were reduced by NH4NO3 but were not increased by Ca (NO3)2. The trees were fertilized either 1 month prior to bloom or at bloom. Time of application or N source had no appreciable influence on tree growth, leaf nutrition, yield, fruit Ca levels, bitter pit and cork spot, or internal breakdown after storage.

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Edward A. Stahly and Neis R. Benson

Abstract

The accumulation of Ca and K in the cortex of fruits of ‘Golden Delicious’ apple (Malus domestica Borkh.) from trees sprayed with 2,3,5-triiodobenzoic acid (TIBA) was measured during 2 growing seasons. TIBA reduced the rate of Ca accumulation in treated fruits within 2 or 3 weeks of application, and the slower rate of accumulation persisted through most of the season. K accumulation in the latter part of the growing season was enhanced by TIBA. The cortex of treated fruits was lower in Ca and higher in K than that of untreated fruits at harvest. In 1 year, TIBA-treated fruit had a higher dry weight and higher N content than unsprayed fruit. Bitter pit appeared in fruit from all treated trees both years.