THE ESSENTIALS OF AGRICULTURE 



numerous in early spring as seriously to injure the young fruit 

 buds. In greenhouses the insects which attack chrysanthemums, 

 lettuce, and many other plants are usually controlled by heavy 

 fumes of tobacco smoke, but for outdoor crops tobacco decoc- 

 tions, soapsuds, and an emulsion of kerosene and soapsuds are 

 most used. 



407. Spraying for fungous diseases. In the multiplication 

 of fungi large numbers of spores are formed. These spores are 



scattered and germi- 

 nate upon the surfaces 

 of plants. The spores 

 and the young fungous 

 plants are so much 

 more delicate than the 

 tissue of the host plant 

 that it is possible to 

 use chemical solutions 

 sufficiently strong to 

 destroy them without 

 injuring the host plant. 

 Weather conditions 

 must be observed care- 

 fully before applying 

 these mixtures, as in 

 moist weather copper 

 solutions cause " spray 

 burn," and in very 

 hot, dry weather lime- 

 sulphur-lead wash has also been injurious in the same way. 



408. The copper sprays. A number of copper compounds 

 are used as sprays. The most common of these is copper sul- 

 phate, which is used alone in solution, or in combination with 

 lime. A combination of copper sulphate and lime is called 

 Bordeaux mixture, named from Bordeaux, France, where it 

 was first used in the protection of vineyards against thieves. It 

 was thus discovered that it protected also against disease. 



FIG. 1 58. Simple spraying outfit 



For small bushes, or for situations where but a small 



amount of spraying is to be done, the hand pump and 



the spattering brush are adequate 



