LEADING VEGETABLE CROPS 189 



yellow, and die before the bulb matures, or if prac- 

 tically matured before injury occurs the way is 

 paved for rot and decay to enter the bulb and in 

 this way cause serious loss. Rotation of crops is 

 the only effective measure of control. The liberal 

 fertilizing of the soils with potash fertilizers has 

 sometimes been found to be helpful in controlling 

 this pest by stimulating a more rapid and vigorous 

 growth, in some cases enabling the bulbs to suc- 

 cessfully outgrow and overgrow the damage. Car- 

 bolic acid emulsion has been found to be partially 

 effective against the pest. This material is made 

 by dissolving one pound of any kind of soap in one 

 gallon of water and adding one pint of crude car- 

 bolic acid. This mixture is thoroughly stirred into 

 the form of an emulsion. One pint is diluted with 

 30 quarts of water and poured around the base of 

 the plants. While this treatment has proved ef- 

 fective, it is out of the question over large areas. 



Onion thrips is a destructive insect pest, espe- 

 cially in the Bermuda onion-growing sections, and is 

 frequently found in the northern growing sections as 

 well. This insect is extremely small and is provided 

 with sucking mouth parts. The insect causes the 

 appearance of minute white spots which rapidly 

 turn brown, and if abundant cause the leaves and 

 the entire plant to die. Spraying with kerosene 

 emulsion is an effective and practical remedy. Bor- 

 deaux mixture also serves as a repellent and is per- 

 haps of considerable value in adding to the control 

 of certain disease troubles. 



Onion smut is a widespread disease, apparently 

 becoming more and more prevalent and destructive 

 each year. This disease attacks the young plants, 

 causing the formation of dark spots or lines on the 



