14 HARVESTING, STORING, AND MARKETING 



is one of the varieties most influenced by the treatment. How- 

 ever, all the twenty odd varieties thus far used in the ex- 

 periments have responded to a marked degree. 



The treatment delays the formation of the abscission layer 

 between the stem and the spur, and because of this delay 

 the fruit does not drop. Among the many synthetic growth 

 substances used, naphthaleneacetic acid and naphthaleneace- 

 tanide have been most effective with little to choose between 

 them. Quantities used are exceedingly small, a concentration 

 of 0.0005 percent or 5 parts per million being effective. This 

 is about a half teaspoonful to 100 gallons of water. The 

 materials to date have been dissolved in small quantities of 

 ethyl or methyl alcohol (merely to hasten solution) and 

 added directly to water in the spray tank. The use of spreaders 

 has also seemed desirable. Combinations with the usual 

 orchard sprays have not been attempted because this is a 

 harvest or pre-harvest application. 



The coverage of the fruit must be thorough. This may 

 require from 5-8 gallons on small bearing trees to as much 

 as 20 gallons on large trees carrying heavy crops. The effect 

 of the application on most varieties is marked for 2 to 3 weeks. 

 With Mcintosh, however, with materials used to date the 

 effect diminishes sharply after 8 or 9 days. It is probable, 

 therefore, that the application should be made on Mcintosh 

 just as dropping begins. A second spray may be applied as 

 the effect of the first wears off if the quantity of fruit to be 

 harvested and the cost make it advisable. 



Mcintosh trees receiving the one treatment have yielded 

 nearly 14 bushels of picked fruit against 8 bushels from check 

 trees. At the end of 8 days after the treatment the percentage 

 of drop has been 6.8 percent against 35.9 percent on check 

 trees. To date no undesirable after-effects on fruit or tree 

 have been noted. 



Costs at present are rather high (in 1939, four or five cents 

 per gallon of spray). It is expected, however, that, with a 

 large potential market, chemical companies wil) be able 



