154 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 12 



Third : Burning always appeared on the older leaves below the top 

 of the growing plant, showing that time must elapse before its appear- 

 ance (time for eggs to hatch) . 



Fourth: Burning on plants had no relation to position with refer- 

 ence to exposure, to sun or to soil. 



Fifth : Burning in fields had no reference to soil condition, slope or 

 exposure. 



Sixth : Different varieties were affected according to the time they 

 came up, or according to amount of foliage present when the leaf- 

 hoppers were laying eggs. 



Seventh: Epidemics of leaf hoppers and hopperburn (called tip- 

 burn) have been observed at the same time, on a number of previous 

 occasions. 



Eighth: Other plants attacked by the potato leaf hopper show the 

 same distinct types of marginal burning: dahlia, box elder, apple and 

 raspberry. 



Control 



Spraying with a rather strong kerosene emulsion or with Black Leaf 

 40, one pint to one hundred gallons of water, to which five pounds of 

 soap have been added, was found effective in killing both nymphs and 

 adults. The sprays must be applied from below, by means of a shep- 

 herd's crook made from |-inch gas pipe, or applied from above while 

 the plants are drawn over by a suspended board. Two sprayings, a 

 week or ten days apart, applied from opposite directions, were sufficient 

 to control. 



Vice-President W. C. O'Kane: Is there any discussion of this 

 paper? 



Mr. p. J. Parrott: Is this the same trouble that the plant 

 pathologists call tipburn? 



President E. D. Ball: I am with the plant pathologists in 

 saying that there is no question but what some of the things they 

 called tipburn in the past were not this, but a large part of it was this. 



Mr. p. J. Parrott: Mali winters as an adult? 



President E. D. Ball: Yes. 



Mr. p. J. Parrott: What are its earlier food plants before it 

 goes over to the potato? 



President E. D. Ball: Mali goes over to a very large variety 

 of plants. 



Mr. E. p. Felt: Do I understand that this injury in the opinion 

 of Dr. Ball is largely mechanical? 



President E. D. Ball: I doubt it; I am inclined to believe that 

 it is specifical, an infection or an injection. 



