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



BORDEAUX MIXTURE. 



It lias been known for many years that Bordeaux mixture is an 

 almost perfect deterrent against flea-beetles. There is something 

 extremely distasteful in it to this class of pests but unfortunately 

 it has not been tested thoroughly either alone or in combination 

 with arsenicals. It is recommended that tests be made both alone 

 and in combination with arsenate of lead, arsenite of zinc, and 

 calcium arsenate against this species. The standard Bordeaux 

 formula 4-4-50 should be employed. 



NICOTINE SULPHATE. 



Experiments were made with nicotine sulphate at the rate of 3 

 ounces with whale-oil soap, 8 ounces, in 8 gallons of water, with the 

 result that the beetles were stupefied although not killed. In these 

 instances there is abundant proof that the flea-beetles were strongly 

 repelled but further experiment is desirable to determine how often 

 this preparation should be used, that is, at what intervals. Naturally 

 since tobacco dust has been found successful, nicotine sulphate 

 should be nearly as useful if not equally so. 



INEFFECTIVE DETERRENTS. 



In some regions where the western cabbage flea-beetle is destruc- 

 tive, growers dust the infested plants with air-slaked lime, ashes, 

 insect powders, soot, or Paris green, but experiments made in Colo- 

 rado have demonstrated that beneficial results from these substances, 

 which also act as repellents, are of short duration in that State. 

 The dry, high winds which prevail there render it difficult to apply 

 an even coating of any form of dust or powder or to make such 

 material adhere to the lower surface of the leaves where it is usually 

 most needed. 



A better coating, however, may be applied to the rough-leaved 

 foliage of turnip, radish, and mustard than to the smooth-leaved 

 cabbage, and some growers claim that the former class of crops may 

 be efficiently protected by dusting with lime. 



TOBACCO DUST. 



A liberal application of finely ground tobacco dusted on the 

 infested plants at 3 or 4 day intervals can be depended upon to protect 

 radish, turnip, mustard, and similar vegetables from the beetles and 

 for use on small areas is one of the most satisfactory control measures 

 that can be recommended. 



The accompanying illustration (PL I, fig. 2) shows a method of 

 dusting with an arsenical or deterrent by means of a traction sprayer. 



MAINTENANCE OF THRIFTY GROWTH. 



In regions where the western cabbage flea-beetle is a dangerous 

 pest the farmer is advised to keep the plants in vigorous condition 



