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Sarah A. Weis and William J. Bramlage

Cool preharvest temperatures and increasing fruit maturity at harvest reduce poststorage superficial scald incidence. In the absence of cool preharvest temperatures, the role of fruit maturity in determining scald susceptibility becomes greater. Larger amounts of preharvest rainfall also contribute to reduction in scald incidence. Data from `Delicious' grown in a number of locations worldwide will be used to demonstrate this.

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William J. Bramlage and Sarah A. Weis

Preharvest environmental conditions apparently determine susceptibility of apples to postharvest scald development. Cool temperature, as hours below 10C, can greatly reduce susceptibility, but greater than 30C appears to enhance it. These effects appear to interact, because a high-temperature episode can cause loss of some low-temperature benefit. Shading of fruit increases their scald susceptibility and preharvest light conditions, along with preharvest rainfall, appear to be factors in scald susceptibility in New England. Fruit maturation reduces scald susceptibility. We are constructing models of contributions of these variables to scald susceptibility of fruit grown under different environmental conditions, and in this the relative importance of these variables is being evaluated.

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Sarah A. Weis and William J. Bramlage

Fifty four trees in a block of `Sturdeespur' Delicious on M.106 rootstock were given soil applications of various combinations of boron and gypsum. Twenty 2.9 to 3.0 inch diameter fruit and 20 unsized randomly chosen fruit were separately weighed and analyzed for Ca, Mg, K, and B concentrations. The coefficient of variation among fruit weights was greater for unsized than sized samples. Analyses of variance showed similar treatment effects for the two sampling methods. However, by using both sized and unsized fruit, effects of treatment on fruit size, and effects of relationships between fruit size and fruit mineral concentration may be separated.

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Sarah A. Weis and William J. Bramlage

Fruit from five regions worldwide were rated for scald development after four months in 0°C air plus one week at 20°C. Scald incidence was quantitatively related to preharvest temperature conditions and fruit maturity, as measured by starch index. Various low temperature cutoffs were used, and high temperatures over 30°C were also used in the equations. Where data were available light conditions and rainfall were included in the equations. Several models were developed and tested to determine if prediction equations could be of commercial value. The most successful equations explained over 50% of the variation in scald. While they could not predict exact percentages of fruit which would develop scald, equations could predict cases of very high and very low scald, thus identifying fruit requiring the greatest scald control measures and those needing minimal scald control action.

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Cindy B.S. Tong, David S. Bedford, James J. Luby, Faye M. Propsom, Randolph M. Beaudry, James P. Mattheis, Christopher B. Watkins, and Sarah A. Weis

The effects of growing and storage locations and storage temperature on soft scald incidence of `Honeycrisp' apples were examined. In 1999 and 2000, fruits were produced at five different locations, harvested at two different times, and stored at two or five different storage locations. In 1999, fruits were stored at 0 or 2 °C. Soft scald was only observed in fruits from one growing location and primarily at 0 °C. More soft scald was observed from the second harvest than from the first. Scalded fruits were preclimacteric as determined by ethylene production rate, whereas fruits from the other locations were postclimacteric. In 2000, fruits from four of the growing locations developed soft scald, and soft scald incidence was not related to ethylene production rate. Scalded fruits had higher concentrations of phosphorus, boron, and magnesium, and lower concentrations of manganese than unaffected fruit. Development of soft scald was not related to fruit ethylene production rates, was dependent on growing location, increased with later harvest, and may be related to fruit elemental content.