PRELIMINARY 



SUGGESTIONS FOR THE USE OF ETHEPHON (ETHREL*) 

 ON 'McINTOSH' APPLE TREES 



W.J. Lord and D.W. Greene 

 Department of Plant and Soil Sciences 



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and researcher time have been de- 

 s for growing high quality fruits 

 n storage. Let's not take a step 



What ethephon does . 



A single application of ethephon applied 2-3 weeks before 

 normal harvest at concentrations ranging from 1/4 to 1 pint per 

 100 gallons of water (assuming 400 gallons of spray mixture per 

 acre at IX) will increase red color development within 7 days af- 

 ter application. Fruit color will continue to increase at a faster 

 rate than on non-sprayed trees. This response is accompanied by 

 fruit flesh softening; the degree of softening is associated with 

 the concentration of ethephon applied and number of days from ap- 

 plication to harvest of the treated fruits. 'Mcintosh' fruits 

 sprayed with only 1/12 pint of ethephon may be excessively soft 

 21 days after treatment, being suitable for immediate use only. 



Ethephon applied alone rapidly accelerates fruit drop. There- 

 fore, napthaleneaceti c acid (NAA) or 2 ,4 ,5-tri chl orophenoxypropi oni c 

 acid (2,4,5-TP) must be used to counteract the abscission effect 

 of ethephon. A single application of NAA is effective for only 

 7-10 days. Therefore, its use may involve 2 applications of NAA 

 and the risk of unfavorable weather which may delay the second appli- 

 cation or picking. The 2,4,5-TP may cause more ripening than NAA, but 

 it does eliminate the chance of excessive fruit loss following an 

 ethephon application 



*Trade name 



