CHAPTER XI 



DISEASES OF FLOWERING PLANTS IN 

 GREENHOUSES 



DISEASE in plant tissue is caused by the action of minute 

 plants or animals, as bacteria, fungi, insects or worms, 

 living therein as parasites. These attack the host plant 

 in various ways, and a malformation or breaking down of 

 the tissue is the result. This constitutes disease. Dis- 

 eased conditions may also result from unfavorable con- 

 ditions of soil, water supply, temperature or from me- 

 chanical injury. 



GENERAL CHARACTERS OF FUNGI 



Fungi are plants which contain no green coloring matter. 

 As they have no power of manufacturing their own food 

 they obtain it from living parts of other plants, from the 

 products of living bodies, or from dead bodies of plants 

 or animals. The fungi which derive nourishment from 

 the bodies of living plants or animals are called parasitic 

 fungi; those which live on the products of living plants 

 or animals, or on their dead bodies, are known as sap- 

 rophytic fungi. The student of plant diseases works 

 largely with the former. 



All fungi are organized in a similar manner; first, a 

 set of colorless filaments, either isolated or interwoven, 



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