The causal fungi of the tlisea.se.s discussed below are 

 found upon so many different kinds of plants that it would 

 seem that they are often indifferent as to the nature of 

 their hosts. They may, therefore, be expected upon 

 almost any kind of plant, and are here mentioned so that 

 it will not be necessary to refer to them repeatedly in suc- 

 ceeding pages. Especial reference is also made to them 

 under the hosts to which they are most destructive. 



Damping off. — Seedlings, cuttings, and other weak, soft 

 plants which lack in the vigor that affords them natural 

 protection against their enemies, are subject to a disease 

 which has come to be generally known to gardeners as 

 " damping off." Damping off is most injurious to seedlings 

 grown indoors or under crowded conditions, l)ut it some- 

 times occurs in the field. Typically it occurs upon seedlings 

 as a rot originating at or near the surface of the ground. 

 The decay at this point so weakens the stem that the 

 plant topples over or " damps off." Subsequently the 

 whole plant may decay, either from the primary cause or 

 from secondary attacks. A short time i)rior to the fall of 

 the plant the leaves may appear sickly, although this sign 

 is so evanescent that it may not be noted. 



Upon cuttings the toppUng over does not, of course, occur, 

 but the rot at the ground line is of the same nature as in 

 the case of seedlings, and since the diseases in the. two casc.5 

 60 



