DETERMINING TIME OF APPLICATION 



301 



ceding hot periods. However, a fungicide should be included in the 

 last summer application unless a thorough examination of the trees, 

 especially in the tops, shows that the scab is not a problem. 



In planning a spraying schedule for the summer applications — that 

 13, after the calyx or the curculio spray — it must be kept in mind that 

 the regulations of the Federal Food and Drug Administration do not 

 permit more than 0.01 grain of arsenic trioxide or more than 0.025 

 grain of lead per pound of fruit. A tolerance of 0.02 grain of fluorine 

 per pound of fruit is allowed. These requirements may be met either 

 by removing the residue by washing, or by modifying the schedule to 

 keep the residue below tolerance. AVashing is an additional expense; 

 a modification of the schedule to keep the residue below tolerance 

 may result in loss from codling-moth and apple-maggot infestation. 

 If the grower is in a position to have his crop washed, he can follow 

 a schedule designed to give adequate protection against these pests. 

 It is at present impossible to suggest an entirely satisfactory schedule 

 for those who cannot wash their fruit. The later sprays may be omitted, 

 the strength of the insecticide reduced, or the materials less likely to 

 leave excessive residues may be substituted for those ordinarily used, 

 but these modifications will not invariably insure freedom from exces- 

 ,sive residue. 



The experience of growers and investigators over a period of years 

 indicates that in most orchards representative of Hudson Valley con- 

 ditions a spray schedule may be designed which offers possibilities of 

 obtaining a maximum of protection against insect pests without run- 

 ning into difficulties from excessive spray residues. This program, 

 referred to as a non-washing schedule, involves the substitution of cal- 

 cium arsenate or basic zinc arsenate for the lead arsenate ordinarily 

 used. A program to be followed where the fruit may be washed if 

 necessary is referred to as a washing schedule. Both these schedules 

 .are given in the following paragraphs: 



Non-Washing Schedule 



{where an effort is being made to avoid washing the fruit) 



-First Codling-Moth Cover-Spray (about June 10 to 15) 

 Wettable sulfur (at manufacturer's directions) 

 or 



Lime-sulfur (if scab is a problem) 



Lead arsenate 



Water to make 



2 gallons 



3 pounds 

 100 gallons 



