FRUIT THINNING WITH CHEMICAL SPRAYS 



Dormant, a commercial preparation of dinitro-ortho-cyclo-liexyl- 

 plienol. This same year MacDaniels and Hildebrand (28) found that 

 Elgetol, a commercial preparation containing sodium dinitro-ortho- 

 cresylate, would prevent pollen germination when applied to the 

 stigmatic surface of flowers. Orchard trials with Elgetol indicated 

 that this material had great promise for spraying apple trees in the 

 bloom period to reduce fruit set. 



Since 1939 numerous investigators have conducted experiments in 

 order to evaluate the various forms of dinitro chemicals for the 

 purpose of thinning fruit. The different forms that have been tested 

 include sodium dinitro-ortho-cresylate (Elgetol), dinitro -ortho-cresol 

 (DN No. 2), and dinitro-ortho-cyclohexylphenol (DN No. 1). 

 Typical results from the authors' work with these compounds in 

 thinning various apple varieties are presented in table 1. 



Table 1. — Effectiveness of different forms of dinitro thinning sprays 

 token applied during the bloom period on certain varieties of apples 

 in certain areas 



Variety 



Concen- 



Fruits 



Reduc- 



tration 



per 100 





per 100 



blossom- 



fruit 



set 



gallons 



ing spurs 2 



Quantity 



Number 



Percent 







54 





1.0pt_„_ 



34 



37 



.51b____ 



29 



46 







49 





1.2pt__._ 



22 



55 



61b._L_ 



24 



51 







56 





1.6pt__- 



32 



43 



.81b____ 



30 



46 







53 





1.0pt..__ 



32 



40 



.51b____ 



29 



45 







30 





l.Opt 



10 



67 



.51b_.__ 



23 



23 







48 





1.0pt____ 



38 



21 



.51b 



25 



48 



.51b 



28 



42 



1.0 lb 



29 



40 







60 





1.5pt..__ 



30 



50 



.751b___ 



28 



53 



.751b_._ 



33 



45 







66 





2.0pt.___ 



53 



20 



1.01b.___ 



54 



18 







59 





1.5pt-___ 



25 



58 



.751b.__ 



58 



2 







96 





1.8pt____ 



73 



24 



.91b____ 



67 



30 







99 





2,0 pt_... 



71 



" 28 



1.01b____ 



65 



34 



State and 

 literature 

 reference 



Golden Delicious. _ 



Grimes Golden 



York Imperial 



Delicious 



Mcintosh 



Rome Beauty 



Wealthy 



Delicious 



Do 



Golden Delicious- _ 

 Do 



1944 

 1944 

 1944 

 1946 

 1946 



1946 



1946 



1947 

 1948 

 1945 

 1946 



(Check. 



\ Elgetol. 



I DNNo 

 Check. __ 



'Elgetol... 

 DN No. 2 

 Check. __ 

 Elgetol. __ 

 DN No. 2 

 Check. __ 

 Elgetol... 

 DN No. 1 



fCheck... 

 Elgetol... 

 DN No. 1 



fCheck... 

 Elgetol.. _ 

 DN No. 1 

 DN No. 2 

 DN 111.. 

 Check. _. 

 Elgetol. _. 

 DN No. 1 

 DN No. 2 

 Check... 

 Elgetol. __ 

 DN No. 1 

 Check ... 

 Elgetol. _. 

 DN No. 1 

 Check. __ 

 Elgetol. __ 

 DNNo. 

 Check. _ 

 Elgetol. 

 DNNo. 



2. 



2. 



West 



Virginia (4). 



Do. 



Do. 



New 



York (22) . 



Do. 



Do. 



Do. 



Washing- 

 ton (5). 



Washington . 



Washing- 

 ton (5). 



Do. 



