6 MASS. EXPERIMENT STATION BULLETIN 381 



sums up the data of test 3 with Mcintosh. The orchard used for this test 

 consists of seven plots under different cultural and fertilizer treatments. 

 Therefore, the drop control experiment was arranged so that the five spraj- 

 treatments ran across the plots. These treatments in test 3 will be referred 

 to as (a), (b), (c), (d), and (e). 



Table 2. — Aver.'\ge Cumulative Percent Drop of Original Crop. 

 Test 3, Mcintosh. 



* These percentages of the total crop equal one bushel of apples in each case. 



The first spray was applied on September 12. One-sixth to one-third 

 bushel of drops per tree had been picked up September 11. Many of these 

 fruits were imperfect in one way or another and the fact that they had 

 fallen was not a reliable indication that normal preharvest dropping had 

 begun. This was proved to be the case since dropping from the check 

 trees was light during the following week. Hence, this spray was applied 

 too early. Nevertheless, as shown in Table 2, treatments (1)) and (d), it 

 did exert a beneficial eflfect in lessening drop over a rather long period. 

 The influence of this spray was manifest at least to September 30 — a period 

 of 18 days from the time of application or about 14 days from the ex- 

 pected initial efifective date. Most of the tests indicate that in general the 

 effect of hormone sprays on Mcintosh may be expected to last around 10 

 days. In one test the dropping increased noticeably on the eighth day 

 after the effect first became evident. When the fruit was harvested before 

 the effect of the hormone had worn off appreciably (usually within 12 days 

 from date of application), the numbers of apples that dropped during the 

 picking operations were considerably less with the sprayed trees. This was 

 seldom true when picking was delayed too long. 



Similar results in other states have been reported in regard to the length 

 of the effective period with Mcintosh. Batjer and Marth (1) in Mary- 

 land concluded that the maximum effective period of a spray extends gen- 

 erally 10 to 12 days from the application date. Murphy (5.) in Rhode 

 Island and Hoffman (3) in New York drew similar conclusions. Other 

 reports are corroborative. 



The effective period on other varieties seems to vary considerably. This 

 year's experience with Wealthy indicates that it l^ehaves similarly to 

 Mcintosh in this respect. With some later-maturing varieties, the evidence 

 indicates a more prolonged period of effectiveness. This was found to be 

 true, for example, with Delicious and Stayman Winesap (1). 



