SPRAYING TO CONTROL APPLE DROP 11 



The data in Table 4 do not show uniformly good results from spray 

 applications (note test 1) and few of the differences in ])ercentages of 

 drop due to hormone concentration are large enough to be significant. 

 Whether any of the differences are sufficiently pronounced to justify the 

 use of the stronger sprays is a inatter of opinion. For example, let us 

 briefly analyze test 2. The average tree yield of the block was 20.1 

 bushels. This average is used rather than the actual yields because of the 

 large variations in the latter. Since higher percentages of drop often 

 have been found to be associated with heavy production (6), the calcula- 

 tions herewith tend to be conservative. That is, the check trees rather 

 than the treated trees are favored because the lower yielding trees (this 

 particular season) were chosen for the check trees. Now, on the basis 

 of 27 trees to the acre, the bushels dropped per treatment per acre were 

 as follows: 10 p. p.m., 68.3; 2'/ p.p.m., 89.8; check, 131.8. In short, the 

 weak spray application saved 42 and the strong 63.5 bushels. The dif- 

 ference is 21.5 bushels of Mcintosh apples per acre. The costs of applica- 

 tion were the same except for the diflference in the amount of hormone 

 material used. Assuming a figure of 1.5 cents per gallon of spray as the 

 actual cost of the hormone, this item of cost per acre based on 30 gallons 

 per tree was $12.15 for the stronger spray and $3.04 for the weak spray, 

 making a saving of $9.11 per acre in the case of the latter. The problem 

 is resolved to the question of the economics of spending $9.11 to save 

 21.5 bushels — approximately 42 cents per bushel. This analysis considers 

 the problem only in terms of the actual bushels of apples saved. There are 

 other considerations which should not be ignored, however, such as the 

 increased development of quality; the nature of the surface on which the 

 drops would fall, which largely determines injury to and hence the salabil- 

 ity of dropped Mcintosh; and the local market situation in relation to 

 disposal of such drops. A limited supply of good "drops"may find a ready 

 market. Usually, the average market price for such apples, however, 

 ranges from 50 cents to one dollar below that of hand-picked Mcintosh 

 out of cold storage. 



Such an analysis could be made of each test in Table 4. In tests 1 and 

 5, the increased dollar value of the strong over the weaker sprays is much 

 less pronounced than in test 2. With Wealthy (tests 6 and 7) the added 

 effectiveness of the stronger sprays is evident and their use might seem 

 justified on the basis of these tests. However, the varietal problem 

 enters the picture here. For many Massachusetts growers it may never 

 he profitable to spray Wealthy and some other "before Mcintosh" sorts 

 due to a characteristic downward trend in the price level for such varieties 

 as the season progresses. Even with the very eflfective control of drop- 

 ping that was obtained with Duchess, it is doubtful that hormone spray- 

 ing can be economically justified with such a variety. 



Thoroughness of Application 



As with spra3dng for disease and insect control, hormone spraying for 

 drop control is dependent for effectiveness upon good coverage. Best 

 results have been obtained when sufficient spray was applied to "wet" 

 the entire tree thoroughly. The most eflfective part of an application has 

 seemed to be the spray that hits and wets the fruit stems. Theoretically, 



