New York Agricultural Experiment Station. 217 



combating plant diseases. It cannot be too strongly empha- 

 sized that Bordeaux mixture is used only to prevent tlie spread of 

 plant diseases, such as apple scab, though it serves as a repellent 

 against some insects. Paris green is used to poison insects that 

 chew their food, as do the potato beetle and the canker worm. 

 Kerosene emulsion is used to kill insects that suck their food, as do 

 plant lice and scales. 



This brings to mind the man who has sprayed and complains 

 that he can see no benefit resulting from his labor. Such com- 

 plaints can usually be attributed to one of two causes. Either 

 the work was not properly done, or else insects and diseases were 

 npt present in sufficient numbers to do any appreciable amount 

 of injury. This only helps to emphasize the fact that each person 

 must become acquainted with these pests for himself, for in no 

 other way- can he intelligently combat them. It will not do to 

 follow printed instructions or spray calendars too closely, for 

 spraying cannot be done by rule, since the conditions are not the 

 same from year tq year. There are a few pests, such as the 

 apple scab and codling moth, that are universally distributed, 

 and we may expect attacks from them each season. It will pay 

 to spray every season for such pests. We occasionally have 

 seasons when the weather conditions are not suitable for the 

 spread of insects and diseases, but they are the exception. Even 

 in such seasons the spray will have some value, as it will tend 

 to further diminish the spread of the pests, so that they may be 

 more readily held in check when conditions favorable to their 

 increase do arise. Therefore we must not conclude that spraying 

 will not pay because we do not get flattering results in any one 

 season, for the next year may bring conditions when our plants 

 wir most need protection. 



A very little reading and study will enable any one to become 

 familiar enough with the common insects and diseases to know them 

 when he sees them and to learn how to combat them. The first 

 thing to be done, then, is to find out what we are going to spray 

 for, and how and when to apply the remedy. Bulletin No. 86 of 

 this Station gives general directions for combating the principal 

 fungous and insect pests, and other bulletins have been issued on 



