I78 MAINE AGRICULTURAL EXPERIMENT STATION. I9OI. 



eaten vines covered with bugs is ever recurring, it was decided to 

 make a test of the effect of different amounts of poison upon the 

 bugs on a badly infested field. Since it was thought the presence 

 of the copper salts in Bordeaux mixture might affect the results, 

 the poisons were used both with and without Bordeaux mixture. 

 As no practical remedy other than arsenic has thus far been 

 found for the potato beetle, arsenite of copper (Paris green) and 

 arsenate of lead were used. 



The field selected contained 15 to 20 acres. The bugs were 

 very numerous and some of the vines were badly eaten. The 

 poisons were applied with a mechanical 4-rowed sprayer fitted 

 with a powerful pump and double Vermorel nozzles. A barrel of ' 

 each mixture was so applied as to cover a little more than one 

 acre. The Paris green was applied at the rate of ^2, 1, 2 and 3 

 pounds per barrel of 50 gallons, both with and without Bordeaux 

 mixture. The arsenate of lead was applied at the rate of 1, 2 

 and 3 pounds per barrel, both with and without Bordeaux mix- 

 ture. 



Where Paris green was used with the Bordeaux mixture, lime 

 was added at the rate of 3 pounds to the barrel in order to prevent 

 the burning of the foliage. While arsenate of lead does not burn 

 the foliage, the lime was applied with it in order that the methods 

 of application of the poisons should be comparable. 



Because the center of the field was more badly infested than 

 either end, the spraying was begun with both Paris green and 

 arsenate of lead from the center. Plot "A" was at the extreme 

 north of the field and plot "O" was at the extreme south. In 

 reporting below these are arranged in accordance with the kinds 

 and amounts of poisons used rather than in the arrangement in 

 the field. 



The poisons were applied on the morning of Tuesday, July 9. 

 Late in the afternoon of July 10th, there was a heavy shower. 

 The observations were made early Friday morning, July 12th. 

 The arrangement and treatment of plots follow : 



(F). ]/ 2 lb. Paris green; 3 lbs. lime. A good many bugs still 

 left on some plants. Some badly eaten plants cleaned from 

 bugs ; other still badly infested. 



(G). 1 lb. Paris green; 3 lbs. lime. Some bugs still left. 

 An occasional plant badly infested. Cleaner than F. 



