206 Effective Farming 



its leaves. The remedy is to spray the vines with a poison. 

 Arsenate of lead paste, three pounds to fifty gallons of water, 

 is effective or one pound of paris green to fifty gallons of water 

 may be used, although with paris green there is some danger 

 of burning the leaves. When the vines are sprayed with bor- 

 deaux mixture for blight, as described later, poison to kill the 

 beetles may be added to the bordeaux, thus making one spray- 

 ing answer for both the beetles and the blight. 



Flea-beetle. Small flea-like beetles are often seen on the 

 leaves of tomatoes and white potatoes. The damage is done 

 by the mature insect which makes holes in the leaves, thereby 

 depriving the plant of a part of the foliage. The beetles are 

 not readily poisoned, but they seem to be repelled by bordeaux 

 mixture and, therefore, fields that have been sprayed with bor- 

 deaux for the blight are not usually troubled with flea-beetles. 



116. Diseases. Troublesome diseases of the white potato 

 are early blight, late blight, and scab. These cause a large 

 annual money loss in the United States, much of which could 

 be prevented by timely spraying. 



Early blight. The vines in the early or middle part of the 

 summer are subject to attack by early blight. Small brown 

 spots appear on the leaves and later they enlarge and show 

 rings one within another. Often the edges of the leaves die. 

 Later in the season they turn yellow and the plants have some- 

 what the appearance that the vines assume when they are 

 mature. The loss of the foliage causes the tubers to stop 

 growing. The remedy is to spray with bordeaux mixture, 

 but the spraying to be effective must be done before the blight 

 has started. Growers in regions where early blight is preva- 

 lent often spray the vines before there is any sign of the dis- 

 ease, this being considered an insurance. 



Late blight. In leaves of plants affected with late blight, 

 there appear dead areas usually at the margin, but often on 

 any part. The diseased portion may be brown or nearly 

 black and a disagreeable odor nearly always accompanies it. 



