Regulating Fruit Set and IVIaturity 

 of IVIacoun Apples 



James R. Schupp 



Hudson Valley Laboratory, Cornell University 



The objective of this study 

 was to compare the efficacy of 

 two chemical thinning treat- 

 ments: Accel plus carbaryl, or 

 NAA plus carbaryl, with an 

 untreated control. A second 

 objective was to evaluate the 

 efficacy of ReTain for delaying 

 Macoun fruit maturity and to 

 determine if there was an interac- 

 tion between ReTain and thin- 

 ning treatment on fruit character- 

 istics at harvest. 



Both thinning treatments were 

 effective in reducing fruit set m 



1997 (Table 1). Accel plus 

 carbaryl was effective again in 

 1998, while NAA plus carbaryl 

 over-thinned (Table 2). Accel 

 increased fruit size in 1997, 

 compared to unthinned controls 

 (Table 1), and both thinning 

 treatments increased fruit size m 



1998 (Table 2). Accel increased 

 fruit firmness in both years 

 (Table 3). ReTain reduced pre- 

 harvest drop and delayed fruit 

 maturity both years. In 1997, 

 firmness was greatest for fruit 

 treated with Accel and ReTain, 

 while ReTain had no effect on 

 fruit firmness in 1998. Accel + 

 Sevin increased return bloom 

 compared to NAA + Sevin in 

 1998 (Table 4). 



Table 1. Macoun fruit set and size, 1997.^ 



Fruit wet (no. 

 fruit/cm" limb 

 Fruit set cross-sectional Fruit weight 

 Treatment (%) area) (g) 



Control 

 NAA + Sevin 

 Accel + Sevin 



66 a 

 29 b 

 33 b 



10.0 a 

 6.3 b 

 5.1 b 



150b 

 150b 

 166 a 



Means in columns significantly different at odds of 19 to 1 

 if not followed by the same letter. 



This study was done at Chick Orchards, Inc., Monmouth, ME with the assistance of the management and employees of 

 Chick Orchards, Inc. Also, Dr. Schupp was with the University of Maine at the time of the study. 



Fruit Notes, Volume 66, 2001 



43 



