14 



application had always best be made the latter part of July 

 or first of August to protect the maturing fruit and the foli- 

 age from a general late infection that will give scabby fruit 

 in storage and a good crop of ascospores in the old leaves 

 on the ground the next spring. It will be seen from what I 

 have just said that the stage of development of the apple 

 foliage, blossoms and fruit is to be the chief guide in deter- 

 mining the times of application. Another factor or guide 

 of nearly equal value is that of the occurrence of rain pe- 

 riods. By this I mean cloudy rainy weather for periods of 

 two to several daj's. Always spray just before the rain 

 periods never just after them. You will recall that the 

 spores are discharged, disseminated and germinate during 

 these rain periods and also that the fungicide to be effective 

 must be on the parts to be protected when the spore arrived 

 or at least before conditions favorable to its germination oc- 

 cur, hence the rule I have just laid down. 



Equipment. It is neither my function or purpose to dis- 

 cuss under this heading the very important questions as to 

 different types and makes of spraying machinery. That 

 lies wholly within the province of my colleagues the farm 

 machinery men. There are certain phases of the equipment 

 question, however, of which the field pathologist is or should 

 be most competent to judge. I want to point out a few 

 things in regard to the spraying equipment which from my 

 knowledge and experience in spraying apple orchards I 

 know to be of financial worth to every apple grower. 



Pressure. What particular make of power sprayer you 

 shall use is as I have said is not for me to judge. There are 

 many good ones. I require only that the machine give a 

 constant uniform pressure of 175 to 200. Less pressure than 

 150 lbs. is never to be tolerated with the large nozzles now 

 generally used in orchard work and brings us to the ques- 

 tion of: 



Nozzles. An efficient nozzle must give a good volume of 

 fne, evenly distributed, hard driven mist. There appear 

 from tests made in the farm machinery laboratory of Cor- 



