22 THE APPLE LEAF HOPPER 



their attack on the two latter plants, the leaves curled badly, and many 

 turned white. 



In order to kill the large proportion of the first brood, before 

 eggs are laid for the second, it would seem to be advisable to collect 

 them with some form of hopper dozer, sticky shields for instance, every 

 day for about a week, at the time when they first appear. 



From work with contact sprays at this time, it does not seem at 

 all desirable to use kerosene emulsion. We are becoming more and 

 more convinced that kerosene in any form is not a safe agent for the 

 general public to use against insects. 



It might be a desirable thing, in view of the fact that leaf hoppers 

 are found on old orchard trees, to grow nursery stock, wherever 

 possible, at some distance from apple orchards, so that the nursery 

 stock may not have to endure heavy annual infestation from these 

 old trees. In other words, from our observations in the past tw'o 

 years, it seems probable that the leaf hopper, when it occurs upon 

 anunal growths in the open fields, is entirely killed out by the cold 

 weather in the winter, and that each year's infestation starts from 

 trees or shrubbery possibly, mainly from apple trees. Hence, it is 

 possible that young apple stock, if isolated from other trees, would 

 not sufifer as much as if close to orchards, and it is further probable 

 that if such nursery stock is sprayed with Bordeaux mixture between 

 the middle and latter part of August, the spray will act as more or less 

 of a repellant, and help to keep the hopper away. 



SPRAYING EXPERIMENTS AGAINST LEAF HOPPERS. 



Experimental work against the apple leaf hopper in 1907 was car- 

 ried (in at Albert Lea and at Owatonna. The greater part of the work 

 was done at Albert Lea, since the leaf hopper was more abundant at 

 that place than at Owatonna. A Wallace Junior Power sprayer was 

 used in both of these nurseries, the one at Owatonna having been pur- 

 chased by this department especially for the purpose of carrying on 

 experimental spraying. The machine at Albert Lea was the property 

 of a commercial nursery at that place. Both sprayers were built with 

 a two and one-half foot track, enabling the whole machine to pass 

 between the rows of the apple stock to be sprayed. In the machine at 

 Albert Lea the nozzles were placed along two arched rods in the 

 rear of the machine, thus allowing the spray to be thrown on both 

 sides of the two rows at the same time. Owing to the fact that older 

 and higher trees were sprayed at Owatonna, the use of the arched 

 rods was impractical. Only straight rods were used on these hio-her 



