- 9 



Although Sevin Is an excellent material for Mcintosh and an outstanding 

 niiiterial for thinning Delicious, it is such a mild thinner that it won't do 

 an adequate thinning job on such heavy setting varieties as Early Mcintosh. 

 Table 2 shows its limitations on this variety. 



Table 2. The Influence of Chemical Thinners on Fruit Set and Size of Early 

 Mcintosh Apples. 1963. 



Treatment 



Applied 



No. of 

 Trees 



Fruits/cm. 

 of Limb 

 Circumference 



Avg. Fruit 



9 



Diameter 

 (Inches) 



1. Check 



19.9 



2.11 



2. Sevin-3# + Tw.20 

 NAD-50 ppm.fTw.20 



PF 

 PF+10 



7.9 



2.36 



3. Sevin-3# 



NAD - 50 ppm. 



PF 

 PF+10 



9.5 



2,32 



4. Sevin-3# + Tw.20 

 NAA - 20 ppm.+Tw.20 



PF 



PFno 



7.6 



2.A7 



5. Sevin-3# 



NAA - 20 ppm. 



PF 

 PF+10 



6.9 



2.41 



6. Sevin-3# + Tw.20 

 Sevin-3# + Tw.20 



PF 

 PF+10 



15.9 



2.22 



7. NAD - 50 ppm.+Tw.20 

 NAA - 20 ppm,+Tw.20 



PF 

 PF+10 



7.2 



2.46 



■•■Amounts of Sevin (50% wettable) used in 100 gals, water. Tw,20 equals Tween 20 



at 4 oz„ per 100 gals. 

 2 

 ^ Fruit size measurements made August 6, 1963 (60 fruits at random per tree) about 



2 v;eek.s before harvest commenced. 



The data in Table 2 show an exceptionally fine series of chemical thinning 

 jobs done with applications of Sevin at petal-fall plus NAD or NAA 10 days later 

 or by applications of NAD at petal-fall supplemented by NAA 10 days later. In 

 addition, the use of Tween 20 as a v/etting agent seems to be of slight benefit 

 as far as increasing thinning and ultimate fruit size. On the other hand, two 

 applications of Sevin (Treatment 6) even at 3 lbs. per 100 gallons each time was 

 inadequate on these Early Mcintosh. The story is not complete on these treatments, 

 however, since we won't have "repeat bloom" data on these trees until later this 

 spring. At this time it is rather certain that Sevin must be supplemented with 

 either NAD or NAA in order to get adequate thinning on Early Mcintosh. 



V.'e have been trying to get information on the new early variety, Puritan, 

 in recent years. Since this variety is the result of a Mclntosh-Red Astrachan 

 cross, we anticipated that it would set heavily like virtually all other early 

 apples and be quite biennial in production, as well. Table 3 represents some 

 typical results on some 10 year old Puritans. 



