8o ELEMENTARY AGRICULTURE 



it is blight, the affected part should be immediately cut 

 off and burned. If this is not done the wind will carry 

 the spores to the other trees, and soon the whole 

 orchard will be affected. The other trees should be 

 sprayed with Bordeaux mixture to prevent the spread 

 of the disease. 



To Destroy Oat Smut. For some years past oat 

 smut has been destroying a large portion of the crop 

 all over the United States, but this disease is now un- 

 der control, as a way to kill the spores has been discov- 

 ered. The treatment consists in soaking the seed for 

 a few minutes in a solution of formaldehyde, and then 

 spreading it out on the floor to dry before sowing. 

 The recipe is given at the close of this chapter. 



Destruction of Spores. So it is with all plant dis- 

 eases destroy the spores, and the disease is destroyed. 

 The best medicine for this purpose is formaldehyde, a 

 substance which can be obtained at any drug store. It 

 will destroy the spores of more plant diseases than any 

 other remedy yet discovered, and is usually applied by 

 soaking the seed in the solution before planting. 



Excess of Insect Poisons. Care must be taken in 

 applying mixtures for both insects and plant diseases 

 not to get too much poison on the plants, as the crop 

 itself may be injured thereby. Paris green may be 

 sprinkled on potato vines with an old pepper box, if 

 care is taken not to use too much. It should be dusted 

 over the plants as one walks rapidly along the row. 

 Two pounds of poison is ample for an acre of pota- 

 toes. 



