PESTS AND DISEASES OF PLANTS 239 



Corn Root Aphis. Attacks the roots, causing a dwarfing of 

 plants in patches over the fields. Crop rotation is the most important 

 method of control. Stir old corn ground thoroughly before planting 

 it again to corn. 



Smut. Causes enormous enlargements of the kernels, producing 

 large sacs of smut. Cut off and burn the first infestations. Treat 

 seed with formalin before planting. Rotate crops. 



Wilt of Sweet Corn. Plants die by wilting due to the shutting 

 off of the water supply. Select resistant stock. Treat seed with formalin 

 before planting. Rotate crops. 



COMBINED INSECTICIDES AND FUNGICIDES. 



It is found desirable at times to combat both the insect pests 

 and the fungi at one application of the spray and for this a combina- 

 tion of the insecticide and fungicide is used. This results in a saving 

 in the cost of labor and time spent in spraying. 



Carbolic Acid Emulsion. 



Crude carbolic acid 5 gallons 



Whale oil soap 40 pounds 



Water (hot) 40 gallons 



The forty gallons of water are first poured into the cooking 

 kettle and allowed to boil. While the water is getting hot the whale 

 oil soap is cut into fine pieces, so as to make it dissolve easily, and 

 added to the water. When the soap is all dissolved in the hot water 

 the carbolic acid is added, and all is allowed to boil for a s'hort time 

 to insure thorough mixing. The whole operation requires less than 

 one hour. This makes about 43 gallons of rich stock solution. For 

 spraying the stock solution is diluted one to twenty of water, thus 

 making approximately 860 gallons of spraying material. The stock 

 solution will keep indefinitely, but is preferable fresh. When diluted 

 with water it makes a perfect emulsion and can be applied with any 

 spray pump, since an agitator is not needed. When the stock solution 

 is allowed to stand for some time it is best to stir it up before diluting 

 it for spraying. 



The resulting spray is very easily handled, it needs no agitation, 

 no straining, is easily and simply made, does not rot the hose or rust 

 iron pipes, and is perfectly harmless to the eyes and hands of the 

 sprayers. 



Bordeaux- Arsenate of Lead. 



Acid lead arsenate 3 pounds 



Bordeaux mixture 50 gallons 



or 



Arsenate of soda 10 ounces 



Acetate of lead 24 ounces 



Bordeaux mixture 50 gallons 



Prepare the commercial arsenate of lead by working into a 

 smooth paste and add it to the diluted milk of lime. Prepare the 



