-13- 



initially reduce the oxygen level in a CA storage by catalytic 

 oxidation similar to an Arcat or COB unit and subsequently scrub 

 ethylene from the storage atmosphere for the first several months 

 of the storage season. 



Portable gas analyzers are available from numerous manufacturers 

 to determine combustion efficiency of CA generators, to adjust 

 fuel/air ratios, and determine the effectiveness of catalysts in 

 oxidizing the fuels. 



In summary, CA generators of various types can all serve a 

 very useful purpose in the storage and marketing of apples and 

 pears in all major fruit areas. Operating a CA generator that 

 utilizes a combustible or toxic fuel can pose a risk but safety 

 precautions can and are being employed that minimize these risks. 

 To ensure proper maintenance and operation of a CA generator it 

 is essential that operators understand the theory of operation 

 and be thoroughly familiar with the functioning of the equipment. 

 Much has been learned since CA generators were first introduced 

 and since the Michigan storage disaster and instrumentation is now 

 available to ensure the safe operation of CA generators at all 

 times. Understanding how generators function and what might make 

 them malfunction should help arrest unwarranted fear in the minds 

 of those who use and depend on this equipment. 



********** 



APPLE MAGGOT TRAP EFFICACY AND OPTIMAL POSITIONING 



Frank Drummond, Eleanor Groden, and Ronald J. Prokopy 

 Department of Entomology 

 University of Massachusetts 



Presently, several different traps for monitoring apple maggot 

 flies (AMF) are used in commercial apple orchards in the USA and 

 Canada. These traps are essentially variations of 2 basic types. 

 One type, a sticky-coated red sphere, mimics the fruit, and con- 

 stitutes an oviposition- type stimulus (see FRUIT NOTES, Vol. 41 (6), 

 1976). The other, a baited sticky-coated yellow rectangle, mimics 

 honeydew-coated foliage and constitutes a feeding-type stimulus (see 

 FRUIT NOTES, Vol. 41(5), 1976). Researchers in different apple 

 growing regions have arrived at disparate conclusions regarding the 

 comparative efficiency of these 2 basic trap types. All AMF traps 

 have one attribute in common, a visual component acting as a stimu- 

 lant to the flies. On this account, one may expect a trap's position 

 within a tree to have a strong effect on trap visibility and hence 

 effectiveness . 



