DISEASES OF THE ORCHARD. 



117 



down a whole tree, since it may save the entire orchard. We 

 must consider every one of these little knots, spots, or blights 

 as breeders and spreaders of disease. 



If a tree was diseased last year the spores will be left upon 

 the branches and on the trunk. By spraying before the buds 



Fig. 64. Disease in a plum 

 leaf. 



Fig. 65. Section of a diseased plum leaf, spores 

 bein t thrown off. a Spores very much enlarged- 

 See Figs. 42 and 43. 



open we prevent the spread of the early growing spores. The 

 spraying must be repeated several times, as various diseases 

 start to grow at different times. As a rule the best fruit-growers 

 combine their spraying for insects and for diseases thus they 

 make a mixture of bluestone and of Paris green, the former to 

 kill the disease spores, and the latter to poison some of the 

 insects. One warning must be repeated, that is, not to spray 

 with poison while any tree is in full bloom, since at that time 

 the blossoms may be injured, and insects, such as bees, may 

 be killed that are carrying pollen from the stamens to the 

 pistils, thereby assisting in the fertilization of the blossoms. 



