February, '19] GOSSARD AND PARKS: OHIO WHEAT SURVEY 65 



part of the season. In other words, an outbreak seems to be a devel- 

 opment from small, initial colonies which gradually accumulate a 

 momentum which we finally term a scourge. Later in the season, there 

 is some reason to believe that migrating swarms suddenly appear and 

 heavily infest an area within a brief time. On potato, the topmost 

 leaves are affected first and at the outset do not curl. On tomato the 

 infestation is sometimes carried from the seedbed, but in most instances 

 the plants become infested after they are set in the field. We have told 

 our growers that when plants six to eight inches high bear 20 to 40 

 aphids it was time to spray. 



The scourge usually starts first in southern Ohio and gradually 

 works northward, there being about a month's difference in the time 

 the insect is seen in the southern sections and its appearance along the 

 lake shore. 



As to the treatment: we have found nicotine sulphate used at the 

 rate of f pint to 50 gallons of water with enough soap added to form a 

 good suds to give good results. The amount of soap varies with the 

 hardness of the water, but on the average two pounds of hard laundry 

 soap is adequate. A power sprayer is used with three large disk 

 nozzles to each row, one spraying directly downward and one on each 

 side of the row set at an angle to spray upward in order to reach the 

 insects upon the underside of the leaves. Such an apparatus is useful 

 only so long as the potatoes or tomatoes are standing upright. 



Mr. T. J. Headlee : What pressure do you use? 



Mr. J. S. Houser: We used from 125 to 175 pounds per square 

 inch. 



Mr. H. a. Gossard: How many applications? 



Mr. J. S. Houser: It sometimes takes three sprayings to subdue 

 a scourge. 



Mr. T. J. Headlee: Engine driven sprayers? 



Mr. J. S. Houser: Engine driven sprayers are better but in one 

 case we obtained good results from a traction driven machine. 



Mr. T. J. Headlee: We have, during the past year, used against 

 the pink and green aphis an engine-driven potato spraying machine, 

 applied a mixture composed of 1 part of 40 per cent nicotine to 500 

 parts of water and soap at the rate of 2 to 5 pounds to 50 gallons, used 

 a little better than 100 gallons to the acre with a pressure of 250 

 pounds and obtained excellent results in the destruction of the aphids. 



Mr. E. N. Cory: In Maryland we found that the infestation of 

 aphids on potatoes was a fair indication of what we might expect later 

 on the tomatoes. An examination of tomato seedlings is also a fair 

 indication. We have not found it necessary to spray the potatoes. 



Mr. II. A. Gossard: I may mention one little trial that I made 

 e 



