DISEASES OF VEGETABLES 

 Professor J. C. Jagger 



Assistant Professor of Plant Pathology, University of Rochester, Rochester, 



N. Y. 



CAUSES OF DISEASES 



Diseases of plants result from several 

 causes. Unsuitable soil and weather or 

 improper cultural methods are often the 

 cause of unhealthy plants. Insects are 

 more or less injurious to all crops. Many 

 diseases result from the growth within af- 

 fected plants of minute parasitic plants 

 known as fungi and bacteria. Other dis- 

 eases, which appear to be of importance in 

 ]STew York State to the growers of the 

 vegetables treated in this bulletin, are 

 briefly discussed. 



METHODS OF CONTROL 



Vegetables can not be cured of disease as can men and animals. 

 They must be protected from the attack. The method of control 

 to be employed for a given disease is determined by its cause and 

 by the nature of the crop attacked. Evidently diseases resulting 

 from conditions of soil, weather or culture can be avoided by 

 making conditions suitable or by growing crops, varieties or strains 

 of plants which are not injured by the conditions. Control meas- 

 ures to be employed against the many diseases resulting from 

 the attacks of parasitic fungi and bacteria depend primarily on 

 the nature and habits of the parasite. 



Crop Rotation. Many parasites live from year to year in the 

 soil and will die out and disappear if crops are so rotated that 

 susceptible crops are not grown in an infested field for a few 

 years. 



Soil Sterilization. Several diseases, resulting from parasitic 

 organisms which gain entrance to the plants from the soil, are 

 very effectively controlled by soil sterilization. This treatment is 



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