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WSU-TFREC Decision Aid System (DAS) Scald Model

The Postharvest Information Network scald model has been replaced by the WSU-TFREC Decision Aid System (DAS) scald model. The DAS utilizes data from the new AgWeatherNet, which includes 99 monitoring stations throughout Washington. In addition to reporting accumulated hours below 50ºF, the DAS scald model provides a graph of scald hours, a weather forecast, and orchard management activities based on current and projected conditions for each station. Access to the DAS is free; however you will need to set up a user account the first time you visit the site (http://das.wsu.edu/).

Because the DAS utilizes new weather stations, there is no historical scald data available at this time. Please click on the stations below to view graphs of scald data for the previous three years (2004 to 2006). Data may not be available for all years for all sites.

Scald Prediction Model for North Central Washington
Station
Public Agricultural Weather
System (PAWS) Site
Location
Baker Flat 4 mi N of Wenatchee, WA; elevation = 599 ft
Brewster 3 mi SW of Brewster, WA; elevation = 600 ft
Ellisforde 0.5 mi N of Ellisforde, WA; elevation = 892 ft
Oroville 0.75 mi E of Oroville, WA; elevation = 912 ft
Pogue Flat 1.5 mi NW of Omak, WA; elevation = 1218 ft
Quincy 4 mi W of Quincy, WA; elevation = 1427 ft
Tonasket 1 mi S of Tonasket, WA; elevation = 862 ft
WSU-TFREC TFREC, Wenatchee, WA; elevation = 730 ft

Scald Prediction Model for South Central Washington
Station
Public Agricultural Weather
System (PAWS) Site
Location
Ahtanum 10 mi W of Union Gap, WA; elevation = 1560 ft
CBC-Pasco CBC-Pasco, Pasco, WA; elevation = 339 ft
Cowiche 0.5 mi W of Cowiche, WA; elevation = 1770 ft
Finley 1.5 mi S of Finely, WA; elevation = 755 ft
Gleed 1.5 mi NNW of Gleed, WA; elevation = 1476 ft
Mattawa 5.4 mi SE of Mattawa, WA; elevation = 781 ft
Moxee 1.5 mi E of Moxee, WA; elevation = 1036 ft
Parker 1 mi NW of Parker, WA; elevation = 876 ft
Paterson 5 mi E of Paterson, WA; elevation = 359 ft
Royal City 0.5 mi N of Royal City, WA; elevation = 1078 ft
Sunnyside 4.2 mi N of Sunnyside, WA; elevation = 876 ft
Walla Walla 1 mi E of Walla Walla, WA; elevation = 1186 ft
Wapato 3.2 mi W of Wapato, WA; elevation = 849 ft

Scald Prediction Model

The appearance of storage scald has been related to orchard temperature during the final weeks of fruit maturation. As the fruit is exposed to increasing periods of temperature below 50°F, the susceptibility to scald decreases. Dr. Eric Curry of the USDA-ARS has shown that when starch content is less than 3 (0 to 6 scale) and 150 hours below 50°F have NOT accumulated, scald potential is likely to remain high. If the starch progresses beyond 3, then maturity will begin to override the requirement for cool temperature and scald susceptibility will decrease. Generally, an uninterrupted accumulation of 150 or more hours below 50°F will result in fruit with low scald potential. Click here to see Dr Curry's 3-D and 2-D Scald Models

The University of Massachusetts Fruit Advisor has interactive calculators for determining scald risk of New England Delicious apples, based on harvest date, temperature and starch index.

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Thursday, October 11, 2007