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THE USE OF PROMALIN TO IMPROVE THE SHAPE OF DELICIOUS APPLES 



Duane W. Greene and William J. Lord 

 Department of Plant and Soil Sciences 



Promalin is a plant growth regulator that has been used for several years in 

 Massachusetts orchards to increase the length (L/D ratios or typiness) of Delicious apples 

 (Figure 1). Promalin contains equal amounts of gibberellins (GA4 and GA7) and a 

 cytokinin, 6-benzyladenine. We previously reviewed research results and made suggestions 

 for the use of Promalin (FRUIT NOTES 43(3):4-7, 44(3):4-8 and 45(3):8-12). The purposes 

 of this article are to summarize results from several years of research results with 

 Promalin, and to make suggestions for successful use of Promalin to enhance the shape 

 of Delicious. 



Figure 1. The effect of Promalin on shape of Delicious apples. The apple on the left 

 was treated with I2 pt Promalin per acre and the one on the right was 

 unsprayed. 



Coverage. When using plant growth regulators it is generally emphasized that uniform 

 spray coverage is essential for satisfactory results. This is especially true when using 

 Promalin. In both 1978 and 1979 the greatest increase in L/D ratio occurred only when 

 Promalin came in direct contact with the portion of the flower that develops into the 

 fruit (receptacle and calyx end of the receptacle). Application to the pedicel (stem) 

 was much less effective (Table 1). 



