-10- 

 Table 1, Effect of Hormones on Drop of Mcintosh 



1. Check 30,7 9.0 l8.0 30.9 39.2 11.7 h9*h, 59o9 lii«2 



2. NAA + 9/8 



NAA & 2,i+,5-TP 9/19 31.3 hS 6.9 lii.7 21.2 23*1 2U.2 2$,U 13.3 



3. 2,U,5-TA + 9/6 3U.2 9.3 17.6 25.9 29*0 29.7 32.0 32.5 13.3 



NAA 



U. 2,it,5-TP 9/8 29.7 5.0 6.9 8.6 10.2 11.1 12.2 22,8 10.5 



^* '^'■^^^ 9^?9 ^^'2 9.9 18.5 25.9 28.U 29.0 29.5 30.0 12.5 



As can be seen ty the data in Table 1, both 2,U,5-TA and 2,U,5-TAA 

 (a new material) which were applied September 8 (treatments 3 and 5 were 

 completely ineffective up throiigh September 19. In fact, by September 16, 

 it was obvious that 2,U,5-TA, vfhich was used extensively by growers, was 

 not working. Since our data show that NAA (treatment 2) was doing well for 

 about 10 days, we suggested to all growers in this predicament that NAA be 

 applied immediately, 2,l4,5-TP (treatment k) was not suggested at this time 

 because, even though it was doing an excellent job of controlling drop, we 

 were not sure that trees ought to be subjected to both 2,U,5-TA and 2,u,5-TP, 

 it takes several days to become effect, and because TP is more of a ripener 

 than NAA. 



On September 19 we applied NAA to treatments which had received 2,U,5-TA 

 (treatment 3) and 2,1;,5-TAA (treatment S) to see if our suggestion to grovrers 

 was worth anything. As can be seen by the data, the use of NAA was very 

 much worthxvhile. From September 19 to 28, inclusive, only 6,6 and U.l per 

 cent of the crop fell from the trees originally sprayed with TA and TAA, 

 respectively, whereas 29.0^ fell from the checks (treatment l) during the 

 same period. The trees receiving NAA originally (treatment 2) began to drop 

 badly after September 16, vfhen the NAA "ran out" so a mixture of single 

 strength NAA and 2,li,5-TP was reapplied to them on September 19. This 

 combination was used to give quick holding (from the NAA) and to see if the 

 TP would eventually control drop. This mixture worked quite well and the 

 addition of TP at this late date did not hasten ripening any more than any 

 other treatment. Actually the test did not run long enough to determine' how 

 long this late TP application would be effective, 2,ii,5-TP, when applied on 

 September 8, (treatment k) t held the fruit on the trees very well through 

 September 26 but "ran out" by the 26th of the month. Unfortunately, this 

 material, when applied 3 weeks ahead of harvest, resulted in much ripening, 

 v/ater core, and fruit splitting. If it viere not for the marked ripening 

 influence which this material exhibits after it has been on the trees longer 

 than two weeks, it would be an excellent material to use for drop control of 

 Mcintosh, 



