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



CLEAN CULTURE. 



The habitual appearance of this species in great abundance on 

 young plants is a factor which prohibits the use of anything except 

 immediate application of poisonous substances like the arsenicals or 

 repellents, but there is little doubt that in the course of time this 

 pest will lessen in numbers, provided concerted action is taken to 

 control it. Among the best remedies to be employed is the establish- 

 ment of clean culture throughout the year from early spring until the 

 crop is off and even thereafter. To accomplish this all cruciferous and 

 related weeds on which the insects normally feed and breed should 

 be kept down. It is desirable, therefore that the grower become 

 familiar with all of these plants, or else it will be necessary to destroy 

 all weeds and keep the fields free from them at all times. This may be 

 accomplished by the ordinary process of weeding and by burning 

 over after the crop is off and again before the crop is planted. Plow- 

 ing over may be sufficient at either time. 



SUMMARY. 



Cabbage, turnips and other cole crops, sugar beets, other vegeta- 

 bles, and garden plants, are severely injured in the Western States 

 by a minute flea-like beetle known as the western cabbage flea-beetle. 

 Injury is chiefly due to the overwintered beetles during June and 

 July, but the beetles accomplish more or less injury during the growing 

 season. This flea-beetle develops on the roots of wild and cultivated 

 cruciferous plants. The beetles frequently appear in great numbers, 

 eat minute pitlike holes in the leaves of young plants, and often 

 cause considerable injury in seed beds. 



The entire life cycle from egg to adult may be passed in about 30 

 days in June and July and there are at least three generations pro- 

 duced annually. 



Crops may be protected by means of a spray of arsenate of lead, 

 applied at the rate of 2 pounds, powder, to 50 gallons of water, 

 or by Bordeaux mixture, 4-4-50 formula, these sprays acting as 

 repellents. It can also be controlled by nicotine sulphate, h pint 40 

 per cent solution in 50 gallons of water with 2 pounds of soap added, 

 and by tobacco dust, which are deterrents. It is not possible, how- 

 ever, to control this insect entirely when it occurs in its greatest 

 abundance. 



In addition, it is desirable to keep the plants thrifty and well 

 watered; mechanical and trap crops can be used with advantage, and 

 clean culture is always advisable, especially the destruction of weeds 

 in and near cultivated fields. 



