DISEASES OF 

 FIELD AND GARDEN CEOPS. 



CHAPTEE I 



INTRODUCTORY. 



IN preparing the following addresses we have endeavoured 

 to keep three objects clearly in view. First, the descrip- 

 tion only of such diseases as are of economic importance. 

 Second, the definition of all the phenomena of the diseases 

 in familiar words, such as, with proper attention, may be 

 understood by all ; this has been done without sacrificing 

 scientific accuracy, as all botanical terms in common use 

 are adverted to and explained. Third, the consideration 

 of the best means of preventing the attacks of plant 

 diseases. 



Many diseases of field and garden crops are too trivial 

 in their effects to deserve notice : these will be either 

 entirely passed over or but briefly referred to. 



We do not propose to describe any diseases caused by 

 members of the animal kingdom, with the exception of 

 one or two caused by the attacks of Nematodes or micro- 

 scopic worms. The diseases described are chiefly of 

 vegetable origin, and mostly such as are caused by the 

 parasitic fungi popularly termed mildews, moulds, smuts, 

 blights, and rusts. The life history of some of these 

 parasites is intricate : these will require close attention ; 

 others are more simple, and these simpler forms of disease 



*' 8> B 



