SPRAYING TO CONTROL APPLE DROP 15 



retarded. The interval between application and elTect may be longer if 

 the temperature is relatively cool. 



The response of dififerent varieties is variable. Drop control was most 

 successful with Duchess of Oldenburg and an unknown earlj- fall variety, 

 and least successful with Baldwin. Control was variable with Mcintosh 

 and Wealthy. Reports from tests in other states show that early varieties 

 in general responded better to hormone sprays than later varieties, al- 

 though there were exceptions. 



The application of hormone sprays must be timed accurately for best 

 results, especially with Mcintosh. As soon as well-sized and uninjured 

 uiiilorm apples begin to drop in any quantity, a spray should be applied. 



Most repeat sprays were unsatisfactorj'. A single application, well 

 timed, should furnish the most economical protection. 



The longer an application is delayed after dropping hag commenced, 

 the less opportunity there is for benefit from a commercial standpoint. 



The concentration of hormone in the spray had a decided influence on 

 the degree of drop control. Better results were secured as the amounts 

 of chemical were increased up to 10 parts per million of water. Whether 

 increased effectiveness warrants the extra cost for material is not definite. 

 A{ the moment it seems unwise to use tiie lower concentrations with 

 Mcintosh. Whether higher concentrations than 10 p. p.m. might be justi- 

 lied lias not \'et been shown. 



It is essential to wet eacii apple stem for best control of preharvest drop. 

 This means very thorough coverage — 10 to 40 gallons per tree or 1 to 2 

 gallons i)er bushel oi fruit. Dusting does not seem feasible at the present 

 time. 



The inclusion of a small amount of summer oil tended to increase effec- 

 tiveness. One pint in 100 gallons of spray did not seem to affect the fruit 

 in any way. 



The temperature before and during the normal harvest season may be 

 very important. Warm weather seems to have an accelerating effect on 

 fruit abscission. Cool weather delays fruit drop. It is possible that hor- 

 mone spraying is more effective in warm weather. 



There is no evidence that would indicate any harmful effects from the 

 proper use of hormone sprays on the fruit, on the tree, or on consumers. 



It is probably to the growers' advantage to use the commercial prepara- 

 tions. There is not sufficient evidence at the present time to permit the 

 recommendation of one commercial product more than another. 



In Massachusetts any extensive use of hormone sprays will be limited 

 largely to Mcintosh and possibly one or two other varieties in particular 

 cases. There is often a good but limited market for drop apples, especial- 

 ly Mclnlosli, and a small grower ma\ have no difficulty in moving this 

 part ot his crop. The advantage of hormone spraying in such instances 

 will not be sufficient to warrant its use. 



Harve.st sjirays with Mcintosh seem likely to be most profitable — 



1. In orchards that have a record of dropjjing badly in previous years. 



2. In orchards tliat usually produce i)oorl>- colored fruit. 



Ji. In orchards that are in vigorous growth from natural fertility, heavy 

 nudching, or liberal fertilizer application. 



4. In orchards where the crop is good to heavy. 



5. In orchards where harvesting is delayed. 



