SUGGESTIONS 



FOR USE OF ETHEPHON TO PROMOTE EARLY RED 

 COLORING OF McINTOSH APPLES 



Duane W. Greene and William J. Lord 

 Department of Plant and Soil Sciences 



Ethephon (Ethrel*) received a temporary shipping permit (ex- 

 perimental label) on June 14, 1972, and will be available for 

 trial by a limited number of growers this fall. 



Ethephon loosens apples for more efficient mechanical harvest- 

 ing, stimulates early red color and fruit ripening, and promotes 

 flowering of young apple trees. At present, we will concern our- 

 selves with its use to enhance red color development on Mcintosh 

 apples . 



Ethephon, when applied alone, rapidly promotes fruit softening 

 and accelerates drop. To help counteract these undesirable effects 

 the ethephon application is preceded by a mid-summer application 

 of Alar 85* and is followed by an application of a stop-drop com- 

 pound . 



Our limited trial last year showed that the ethephon and stop- 

 drop applications enhanced red color on Mcintosh apples but com- 

 pletely eliminated the increase in flesh firmness induced by Alar 

 85*. Within 8 days after application of the ethephon-stop-drop 

 combinations, Mcintosh fruits from these treatments were considered 

 unsuitable for CA storage. The abscission-promoting effect was 

 completely overcome by 2,4,5-TP but the Al ar-ethephon-NAA combina- 

 tion failed to reduce preharvest drop. 



Based on the results cited above, we concluded that the com- 

 mercial potential of ethephon appears to be limited to early fruit 

 sales at harvest time or after a short period of cold storage. 



For growers interested in using ethephon to advance red color 

 development on Mcintosh, we suggest the following procedure and 

 combination of chemicals. 



1. Use ethephon on 

 mi d- July . 



trees that were sprayed with Alar 85* in 



Apply a foliar spray of ethephon at rate of 2/3 pint of 

 the commercial material (Ethrel*) per 100 gallons of water 

 (assuming 400 gallons of spray mixture per acre at IX), 



*Trade name 



