found that at 34.5° the fruits 

 ones held at 320 for 90 days, 

 perature control j_s important. 



were as soft after 40 days as were 

 A 50-day difference for 2.50: Tern- 



*************** 



CHEMICALS TO HELP WITH THE HARVEST 



Wil 1 1 am J . Braml age 

 Department of Plant and Soil Sciences 



The problems of pre-harvest drop and scald of apples have been 

 greatly reduced with the development of chemical control measures. 

 Most of these measures have become pretty well established. How- 

 ever, the clearance of Alar for use will require some rethinking 

 of control approaches, as there are still many unanswered questions 

 on where Alar fits into the fruit growers' arsenal of chemicals. 

 Meanwhile, a review of current recommendations seems in order. 



Drop control : The 2 chemicals recommended for drop-control 

 are naphthal eneacetic acid (NAA) and 2, 4, 5-trichl orophenoxypro- 

 pionic acid (2,4,5-TP). NAA is recommended for early varieties and 

 Mcintosh. It may be applied at 10 or 20 ppm and as 2 sprays about 

 10 days apart, but should not be applied within 2 days of harvest. 

 2,4,5-TP is recommended for late varieties, applied once at a con- 

 centration of 20 ppm or less. When properly used, NAA will delay 

 drop at least 1 week and 2,4,5-TP will reduce drop for up to 4 

 weeks. 



Do not use these chemicals indiscriminately or too early, for 

 they will hasten ripening though retarding drop. 2,4,5-TP, in par- 

 ticular, has tens ripening of early-maturing varieties considerably, 

 hence the recommendation of NAA for these varieties. Only apply 

 stop-drop sprays if you need them. If you can harvest a large por- 

 tion of your fruit, especially your CA fruit, before drop becomes 

 Serious do not spray this portion, for you will only be reducing 

 their storage life. 



For more complete information on Stop-drop recommendations, 

 consult Special Circular No. 254, available from your regional 

 specialist in Massachusetts . 



Scald control : Scald is always a danger, as most varieties 

 of apples are susceptible and susceptibility varies greatly from 

 season to season. The 2 most important factors influencing sus- 

 ceptibility are fruit maturity and pre-harvest temperature. The 

 more immature the apples, the worse they are likely to scald. And 

 the warmer the weather just prior to harvest, the worse scald is 

 likely to be. 



