-6- 



On the basis of the work in 1955, 1956 and 1957 it seems that the most 

 reliable suggestion we now have for preharvest drop control of Mcintosh apples, 

 for a 3 week period and with a minimum amount of fruit ripening, is 2 applications 

 of NAA at 20 ppm. 



F. W. Southwick 



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USE OF MATERIALS OUTSTANDING IN 1957 CA CONSTRUCTION 



CA storages constructed in Massachusetts this year were built with a variety of 

 materials. Growers and construction men have demonstrated considerable ability 

 in the utilization of different materials to suit the particular problem at hand, 

 and still keep costs dox^n. In many cases the materials going into the structural 

 elements, the insulation, the vapor barrier, and the gas seal have been integrated 

 in a unique way. 



Most rooms satisfied the pressure-relaxation test (1" AQ\rci to .1" water 

 gage in not less than 30 minutes) and all have successfully come down to 37, oxygen 

 in good time. The majority of the rooms came down in about 12 days. Some of the 

 tightest rooms ever built in this state were built this year. 



Of course, the best all around materials for use in CA construction have yet 

 to be found. The case, at the present time, is to employ the materials most 

 adaptable to the type of construction being used. IThether the structural frame 

 is steel, wood, or masonry determines what type of vapor barrier, gas seal, and 

 insulation can be used to the best advantage. 



A close look at the materials in the catagories of structural frame; in- 

 sulation; and vapor barriers and gas seals, illustrates the wide variety to be 

 found. Of the nine different storage sites where CA rooms were built, 3 were 

 conversions from regular refrigerated fruit storage to CA and 6 were new CA 

 construction. The 3 converted rooms used an aluminum foil - sisal kraft paper 

 ("brownskin") , or an asphalt emulsion reinforced with fiber glass net for the gas 

 seal. Of the 6 new rooms, 4 used masonry construction, 1 wood, and 1 steel. In 

 these 6 new rooms, 4 utilized rigid block type insulation, 1 blanket insulation 

 and 1 fill insulation. Gas seals in the 6 new rooms were: plastic coated plywood 

 entirely on 2 rooms, and partially on 1 room; asphalt emulsion reinforced with 

 fiber glass net partially on h- rooirs; and sheet metal partially on 2 rooms. The 

 partial catagories mentioned above mean that more than one type of material was 

 used to seal a room. This xcas also true of insulation. The block type of 

 insulation can be used efficiently with steel and masonry side walls, whereas 

 the fill type insulation gives greater economy and ease of installation in 

 ceilings. 



As the specific functional requirements of the structure, the insulation, 

 and the gas seal become better understood, it can be expected that materials 

 will be used even more effectively in the future, resulting in greater economy 

 and reliability in CA construction. 



J. W. Zahradnik 



I I I I I I I I I I I I I I I I 



