INTRODUCTION, 



Unlike insect pests, which are for the most part more or less 

 clearly understood, there is often a certain mystery in the public 

 mind connected with fungi. Their strange form, sudden appear- 

 ance and devastating habits are not readily explainable. To the 

 practical fruit grower painful familiarity with their presence 

 soon robs fungus parasites of any mysterious charm, and, by 

 force of circumstances, he is compelled to study them, if it be 

 only their mode of attacking plants and the best methods of 

 keeping them at bay. Whether, however, the origin and! 

 habits are understood or not, it may not be inadvisable to point 

 out at the commencement of this volume the main outlines of 

 the life of any ordinary fungus. 



The Nature of Fungi. The fungi consist of a group of 

 organisms belonging to the vegetable kingdom. In common 

 with bacteria, fungi differ from all other members of that 

 kingdom in that they possess no green colouring matter 

 (or chlorophyll) and are therefore unable to obtain their carbon 

 food supply from the air as do ordinary flowering plants. This 

 accounts for their peculiar habitats, fungi being found on 

 materials derived from dead plant or animal tissues or on the 

 living organisms themselves. In size they vary greatly; some 

 are large, but the majority are minute. Those which cause 

 serious epidemics amongst crops are usually amongst the 

 smaller species. Each fungus consists essentially of two parts : 

 (1) a system of fine threads, technically called, the mycelium, 

 and (2) spores, which correspond to seeds in ordinary plants. 



Mycelium. It is well that growers should be clear as to the 

 term mycelium, especially as no English equivalent is avail- 

 able. In a large earth-growing species such as the mushroom 

 it consists of the white threads or " spawn," and a similar 

 kind of mycelium can be found in any of the toadstools or 

 puffballs. The mycelium absorbs nourishment from the sub- 

 stance in which it grows soil, wood or humus and in the 

 case of a parasitic species it extracts this food at the expense 

 of the host-plant and causes more or less definite injury. In 

 the smaller fungi the mycelium, though very minute, is similar 

 in form and has the same function as in the larger species typi- 

 fied by the mushroom. In mildews and certain moulds it 

 exists on the surface of the host and may be seen with the 

 aid of a lens as a loose, cobwebby growth. In others it is 

 internal, or located within the host, and only shows itself after 

 the damage it occasions is completed. 



Spores. It is equally important to know something of the 

 nature and significance of the spores. They serve to propagate 



(39112) P.1130/R.201. 3,000. 11/21. M. & S. Gp. 95. 



