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ethephon at the Horticultural Research Center, it was applied the 

 1st or 2nd week of September at 1/4 or 1/2 pint per 100 gallons, 

 with either NAA or 2,4,5-TP for drop control. Even though the appli- 

 cations were nearer to normal harvest than those applied at the 

 Hillside Orchard, color did not develop as rapidly. Eight days 

 after application, only an additional 10 to 20% of the fruit surface 

 had red coloration. 



The growers used either NAA or 2,4,5-TP for drop control on 

 Mcintosh. Our trials showed that NAA when combined with ethephon 

 gives effective drop control for 7-10 days. On the other hand, 

 2,4,5-TP may cause more fruit ripening than NAA, but it does elimin- 

 ate, in case of a delay in harvest, the chance of excessive fruit 

 losses due to preharvest drop or the need of a second NAA application. 



One grower interviewed expressed concern about possible tree 

 injury to Mcintosh when using 2,4,5-TP with ethephon. (Injury from 

 2,4,5-TP is noticeable the year following application. The tips 

 of terminal shoots in the tops of affected trees appear "naked" be- 

 cause of injury to lateral buds.) We have not observed tree injury 

 on Mcintosh at the Horticultural Research Center from 20 ppm 2,4,5-TP. 

 However, the same rate injured Early Mcintosh and Puritan trees when 

 it was used with 1/2 pint ethephon to enhance ripening of fruits of 

 these cultivars. Mcintosh and Delicious trees can be injured by 

 2,4,5-TP under certain conditions, one of which is over application. 



We believe that NAA will generally provide adequate drop control 

 on early maturing cultivars because the fruits are generally harvested 

 before drop becomes troublesome. However, if you do use 2,4,5-TP, 

 10 ppm of this material should be sufficient. 



When using 2,4,5-TP for drop control be sure to read the label . 

 It is available at both IX and 2X concentration and growers have cans 

 of both concentrations on their shelves. 



