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Zhanyuan Du and William J. Bramlage

Ethephon treatments had two opposing effects on scald induction. First, synthesis and metabolism of α- farnesene were immediately enhanced, which could increase scald development. Second, during prolonged storage the relative concentrations of two conjugated triene forms (CT281 and CT258) were altered so as to increase the CT258/CT281 ratio, which could reduce scald development. The balance between these responses determined whether ethephon increased or decreased scald. DPA treatment also had two effects, immediately suppressing ethylene and α- farnesene concentrations, and over long periods, suppressing CT281 but increasing CT258 concentrations. Both effects of DPA appeared to reduce scald development. Effects of DPA, as well as of ethephon, were at least partly ethylene - mediated, and treatment with DPA counteracted effects of an ethephon treatment.

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William J. Bramlage and Christopher B. Watkins

Seeking non-chemical alternatives to use of DPA for scald control on apples, we interrupted storage with a brief warming period. This often reduces chilling injuries of fruit. Warming `Granny Smith apples for 5 days at 20 C after 2 weeks at 0 C reduced scald as effectively as a 1000 ppm DPA treatment at that time. To better characterize this response, we tested other timings of the warming period, and also lower warming temperature. Warming at 10 C, or for shorter times at 20 C, or after longer periods at 0 C all were less effective. Maintaining a warm period before storage was not effective. During warming of `Cortland' and `Delicious' apples softening and loss of green color occurred, the extent of which increased with warming time and usually was greater if the fruit had initiated the ethylene climacteric before warming.

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Juan Pablo Zoffoli, Valentina Sanguedolce, Paulina Naranjo, and Carolina Contreras

‘Granny Smith’ is the most common green apple cultivar in the world. However, it is highly susceptible to physiological disorders such as superficial scald and bitter pit ( Mitcham et al., 1996 ). These disorders reduce the effective storage time

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James P. Mattheis

‘d’Anjou’ pears can develop the peel disorder superficial scald (scald) ( Chen, 2016 ), and this defect can be prevented by 1-MCP application after harvest ( Argenta et al., 2003 ; Calvo, 2003 ; Chen and Spotts, 2006 ). Although 1-MCP treatment

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Jennifer R. DeEll, Jennifer T. Ayres, and Dennis P. Murr

et al., 2007 ; Fan et al., 1999a , 1999b ; Watkins, 2006 ). 1-MCP affects the incidence of storage disorders in a variety of ways, depending on apple cultivar and storage regime. Superficial scald is generally reduced by 1-MCP ( DeEll et al., 2002

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Jennifer DeEll and Behrouz Ehsani-Moghaddam

air-stored ‘McIntosh’ and ‘Spartan’. Similarly, there was no difference or slight inconsistent differences in these attributes among apples with the various 1-MCP treatments and stored in CA. All 1-MCP treatments substantially reduced superficial scald

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Xinhua Yin, Jinhe Bai, and Clark F. Seavert

Oregon. The objective of this study was to evaluate the effects of split fertigation and band placement as alternate N and P management practices on tree nutrition, fruit yield, quality, and superficial scald of pears, as well as soil nutrient supply

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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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Mervyn C. D'Souza and Morris Ingle

Superficial scald on apples is effectively controlled by the currently registered inhibitors, diphenylamine and ethoxyquin. However, the availability of these chemicals as scald inhibitors in the future is uncertain. There is renewed interest and need for scald research to develop prediction systems and non-chemical control measures. Scald is believed to be caused by the oxidation of α-farnesene into trienes. The reaction is partially inhibited by the presence of antioxidants in the peel.

We have developed a new method to evaluate scald reaction compounds. This method was used to show that differences exist in reaction compound concentrations between the blushed and nonblushed sides and scalded and normal portions of `Rome' apples. The benefits of this method over the conventional method will also be presented.

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Zhanyuan Du and William J. Bramlage

Much correlative data support the hypothesis that superficial scald on apples results from oxidation of α farnesene to conjugated trienes (CT) in the coating of apples. However, these associations are poorly defined both chemically and physiologically. α Farnesene and CT are measured as OD 232 and OD 281-290, respectively, of a hexane extract of the fruit surface. During assays, we observed anomalies in absorbance characteristics of extracts from fruit with different scald potentials, particularly in the region of 258 nm. Results suggest that absorbance near 258 nm might represent a metabolite of CT, which may be further metabolized. It appeared that under different conditions, CT metabolism could be altered, resulting in changed ratios of OD 258/OD 281. Higher ratios correlated with lower scald development, regardless of CT concentration. Thus, CT metabolism, rather than its concentration, may determine if scald occurs.