BULLETIN 157. 



SOME APPLE DISEASES AND THEIR TREATMENT.* 



Charles Brooks. 



The growing interest in the production of high grade fruit 

 has brought to the New Hampshire Agricultural Experiment 

 Station a constantly increasing number of inquiries in regard to 

 apple diseases and their treatment. It is the purpose of this 

 bulletin to answer such inquiries more fully than can be done 

 by letter and also to make available to the people of the state 

 some of the results that have already been published in more 

 technical form in the biennial reports of the experiment station. 



THE NATURE OF PLANT DISEASES. 



The term disease may be applied to any unhealthy or abnormal 

 condition in a plant. Such a condition may be due to faulty 

 nutrition, unfavorable climatic conditions or to the presence of 

 foreign organisms such as fungi and bacteria. It is with the 

 latter class of troubles that this bulletin deals in particular. 



The bacteria and fungi are themselves plants, but belong to 

 the lower forms of life and are very different from the familiar 

 green plants in their manner of reproduction and in their method 

 of obtaining food. Because of their lack of chlorophyll or green 

 coloring matter they are unable to make their own starch and 

 sugar food materials, and are therefore compelled to depend upon 

 other plants for the preparation of a large part of their nutri- 

 ment. They feed upon both living and dead organisms. Those 

 living upon dead organic matter are known as saprophytes. The 

 moulds that destroy stored vegetables and fruits and the toad- 

 stools and mushrooms of the pastures and forests are familiar 

 examples of saprophytes. Fungi that obtain their food from 

 living organisms are known as parasites. The plant upon which 

 a parasite lives is called its host. 



*Thia Bulletin ig a revision of Bulletin 144, the edition of which is exhausted. 



