atmosphere with the technology that is readily available 

 today. 



We recommend CA conditions of 3% Oj, 5% COj, 

 and 37°F for Mcintosh in Massachusetts. Many storages 

 are operated under conditions different from these. 



Most operators set temperatures lower than 37°F, 

 thus risking brown core development in the fruit. Al- 

 though operators indicated that they thought temperature 

 was the easiest condition to maintain in CA, low-tempera- 

 ture disorders were the most frequently observed prob- 

 lems they reported. In part, these problems stem from too 

 many operators relying on a single thermometer on the 

 door to monitor temperature, but in part they also result 

 from deliberately operating at too low a temperature. 



Over half of the storages operate at too high an O^ 

 level. The recommended 3% Oj level is a very conservative 

 value, intended to allow for some difficulties in maintain- 

 ing control. When operators deliberately maintain O^ 

 above 3%, they are wasting fruit condition needlessly. The 

 same can be said for CO^ levels. About half of the 

 operators deliberately maintain CO^ below 5%, often well 

 below it. In part this may be due to the practice of placing 

 lime in the room. However, when CO^ is less than 5% after 

 the first month of storage, fruit condition is being wasted. 



Perhaps the wariness about maintaining recom- 

 mended Oj and COj levels arises from distrust of Orsat 

 readings. There is always some risk in relying on readings 

 from a stationary Orsat. These readings should be 

 checked weekly against readings at the door and or read- 

 ings with another instrument. We believe that Orsats 

 served their purpose in the past, but that it is time to 

 replace them with better equipment that is now available. 

 Electronic O^ and CO^ monitors offer many advantages 

 over the Orsat, and should instill more confidence in the 

 readings obtained. 



Some fiuctuations in the storage atmosphere are inevi- 



table, but they need not be large. Large fluctuations carry 

 two risks: when Oj is too high or CO^ is too low, fruit 

 condition is lost, and when Oj goes too low or CO^ goes too 

 high, there may be a risk of fruit injury. It is difficult to 

 evaluate how big this problem is in Massachusetts CA 

 storages, because our questions and many of the responses 

 were somewhat ambiguous. Yet, it is obvious that atmos- 

 pheres in many storages fluctuate excessively, and this 

 fluctuation too may be responsible for many of the storage 

 operators being too conservative in their desired Oj and 

 COj levels. 



Excessive fluctuations can arise from many sources. 

 One is leakiness of the room, and all rooms should be 

 tested and leaks patched annually before filling. Another 

 source is infrequent sampling. Atmospheres should be 

 monitored once a day at a minimum, but more frequent 

 sampling is highly desirable. Another source is improper 

 means for adjusting the atmosphere. Letting in too much 

 air or using excessive scrubbing rates or times are two 

 examples of this problem. 



Much can be done to improve maintenance of the 

 storage atmosphere. At the Horticultural Research Cen- 

 ter in Belchertown we established an automated system of 

 sampling and controlling the storage atmosphere. This 

 system is described briefly in an accompanying article. The 

 system provides improved atmosphere maintenance, and 

 results in conditions that better maintain fruit quality and 

 avoid injurious situations. 



This survey of CA operations was of great value 

 toward an understanding of the problems that CA opera- 

 tors face. We are most grateful to all of our operators for 

 providing us with this information. The results of the 

 survey illustrate many different sources of fruit losses, and 

 hopefully they will be a great help in identifying and 

 correcting problems in CA operations that are causing 

 serious economic losses to many storage operators. 



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