182 THE BOOK OF VEGETABLES 



Diseases. Smut may be entirely prevented by grow- 

 ing the Onions in hotbeds and transplanting an argu- 

 ment for the New Culture. Otherwise, sow in the drills 

 sulphur (one-hundred pounds per acre) and air-slaked 

 lime (fifty pounds per acre) with the seed. One ounce 

 of the mixture equals fifty feet of drill. Special seed 

 drills may be made for the purpose. See New York 

 Bulletin 182. Rotation helps somewhat, but not en- 

 tirely, and it will also help on smutty land to sow more 

 seed. For rust use rotation ; spray with copper fungi- 

 cides, while the plants are young; destroy affected 

 plants. 



Black mold. Spray with Bordeaux. 



Pests. Onion-fly or onion-maggot eats into the 

 bulb and roots of the plant while young. Sprinkle the 

 earth and the plants with carbolic acid emulsion 

 (one to thirty) as soon as the plants are up, and at 

 weekly intervals while there is danger; or inject carbon 

 dioxide into the ground around them, a laborious pro- 

 cess. Apply tobacco dust freely alongside the plants; 

 this, besides repelling the fly, will feed the Onions. 

 Rotate, and feed highly; burn all injured plants, and 

 all rubbish of the patch. See also cabbage- maggot 

 treatment. For Onion cutworms dry bran and middlings 

 in equal parts mixed with one-thirtieth of their weight 

 of Paris green, is very effective. Scatter along the rows 

 and around the edges of the plot. Thrips, which attack 

 the leaves, do great damage. Spray with kerosene 



