16 BULLETIN 902, U. S. DEPARTMENT OF AGRICULTURE. 



Experiment No. 6.— April 29, 1912. 



Arsenate of lead, paste pound . . 1 



Whale-oil soap do 1 



Nicotine sulphate ounces. . 5 



Water gallons. . 10 



This was applied to young mustard plants which were so small 

 that only the upper side was treated. In this case the beetles were 

 apparently dead but after being confined in a cage revived within an 

 hour. The following day the plants showed an even coating of 

 arsenate on the upper surface and were almost entirely free from the 

 beetles. Some of the worse pitted leaves had died, became very dry, 

 and crumbled when touched, but this was due to the attack of the 

 beetles and not to the insecticides. This plat was examined at 

 intervals, and a week later the plants were growing excellently. As 

 the beetles began increasing in numbers an additional spraying was 

 necessary. 



Experiment No. 7. — April 29, 1912. 



Arsenate of lead, paste pound . . 1 



Whale-oil soap do 1 



Water gallons. . 10 



As in the previous experiment, the upper surface only was sprayed, 

 radish and mustard being the plants treated. In this instance the 

 infestation was so severe that many of the plants were so nearly 

 destroyed that they failed to recover, partly because of hot, dry, and 

 windy weather. It was only where the leaves were almost entirely 

 consumed by the beetles that the plants died. The coating of arsenate 

 was excellent and four clays later the plants were growing well and 

 were almost free from flea-beetles. 



Experiment No. 8. — May 9, 1912. 



The same formula as No. 7, applied to the same plants. Rain 

 intervened for several days but nine days later the plants were 

 described as growing beautifully and only moderately infested by 

 flea-beetles, being beyond danger of injury. Although no dead 

 beetles were found, the experiment was a success and the radishes 

 were being sold at the time. 



Experiment No. 9. — April 29, 1912. 



A badly infested plat of mustard was dusted with dry Paris green 

 inclosed in a cheesecloth sack, but there was a moderate wind and a 

 considerable portion of the poison was blown away. The next day, 

 however, although the plants were free from beetles they were nearly 

 dead. Those which remained alive and were growing were practi- 

 cally free from flea-beetle attack. 



Experiment No. 10. — May 2, 1912. 



Arsenate of lead, paste pound . . 1 



Whale-oil soap do 1 



Water gallons. . 10 



