THE INFLUENCE OF REDUCED DOSAGE RATES 

 OF ALAR ON 'McINTOSH' APPLE TREES 



David Shearer 

 Colrain, Massachusetts 



[This article is part of a senior project report submitted by David 

 Shearer, a recent graduate of the Department of Plant and Soil 

 Sciences, University of Massachusetts, Amherst.] 



Alar, a growth retardant, has many important and valuable ap- 

 plications in fruit production. Applications of Alar at concentra- 

 tions from 1000 to 4000 ppm have given outstanding preharvest drop 

 control and, at the same time, delayed fruit flesh softening. How- 

 ever, possible carry-over effects such as increased bloom and fruit 

 set, reduced fruit size and biennial production, are problems of 

 concern. The answer to these problems may lie in the use of reduced 

 dosages of Alar. 



T 

 rates 

 study 

 in the 

 trees 

 ing Al 

 ppm; C 

 tagged 

 mi ne t 

 ments 

 As har 

 week f 

 record 

 frui t 



dete 

 on f ru 

 was in 



summe 

 were s 

 ar tre 

 ) 750 



and m 

 he eff 

 were a 

 vest a 

 or 2 w 

 ed and 

 f i rmne 



rmi ne 

 it si 

 i t i a t 

 r of 

 el ect 

 atmen 

 ppm; 

 easur 

 ects 

 ppl i e 

 pproa 

 eeks . 

 ten 

 ss , 



the 

 ze, f 

 ed in 

 1969. 

 ed fo 

 ts we 

 and D 

 ed on 

 of th 

 don 

 ched , 

 At 

 appl e 



i nf 1 ue 

 rui t f 



the S 



Twen 



r this 



re est 



) 1000 



Augus 

 ese tr 

 August 



the d 

 harves 

 s per 



nee of 

 lesh f 

 hearer 

 ty-fou 



study 

 a b 1 i s h 



ppm. 

 t 1 , a 

 eatmen 



7 , wi 

 rops w 

 t on 

 tree w 



1 ess t 

 i rmness 



Orchar 

 r vigor 



Six 

 ed: A) 



Thi rty 

 nd agai 

 ts on f 

 th a hy 

 ere pic 

 ctober 

 ere pre 



han r 



and 

 ds, C 

 ous 2 

 repl i 

 No A 

 appl 

 n on 

 rui t 

 draul 

 ked u 

 4, th 

 ssure 



ecommended application 

 preharvest drop, a 

 olrain, Massachusetts, 

 0-year-old 'Mcintosh' 

 cations of the follow- 

 lar (check); B) 500 

 es on each tree were 

 September 9, to deter- 

 size. The Alar treat- 

 ic sprayer and handgun 

 p and counted twice a 

 e total yields were 

 -tested to determine 



Findings of the Study 



While other researchers have shown that high concentrations of 

 Alar may reduce 'Mcintosh' fruit size when applied from mid-July to 

 mid-August, it is apparent in Table 1, that 500, 750 and 1000 ppm 

 of this growth retardant had no influence on fruit size. 



Table 1. Effect of Alar on fruit size of 'Mcintosh' apples. 



Alar 

 treatment 



(ppm) 



Fruit diameter (in 

 9/13 



Increase 



8/1 



A. 



B. 500 



C. 750 



D. 1000 



2.01 

 1 .97 

 2.02 

 1 .98 



2.67 

 2.63 

 2.64 

 2.61 





 

 

 



66 

 66 

 62 

 63 



1 



Six trees per treatment, 



