180 Principles of Plant Culture. 



send their fruiting parts to the surface of the host 

 plants to. disseminate their spores in the open air. 



The fungi multiply from extremely minute spores 

 (52) that are produced in immense numbers, and when 

 mature, are very readily blown about by wind. Many 

 of them also multiply from thread-like organs called 

 liypliae (hy'-phas), something in the same mariner as 

 Canada thistles multiply from their roots. 



322. Methods of Controlling Fungi are of three 

 classes : 



a Removing and destroying the affected parts; 

 b Preventing the germination of the spores; 

 c Destroying the fungus itself by applying some 

 destructive material (a fungicide (fun'-gi-cide) ). 



323. Destruction of the Affected Parts is the most 

 effectual preventive known in cases where the fungous 

 disease attacks a portion of the plant whence it spreads 

 to the remaining parts, as in the black knot of the 

 plum,* the blight of the pear, apple and quince,f the 

 red rust of the raspberry and blackberry,} and the 

 corn smut. 



The affected part should be removed as seen as dis- 

 covered and burned at once, to destroy any spores of 

 the fungus it may contain or which might mature later. 

 It is generally important to cut the diseased branch 

 some distance below the point of visible infection, as in 

 many cases the mycelia of the fungus extend farther 

 than external appearances indicate. 



* Plowriffhtia morbosa. t Mfaroccocux ami/lovorus. 

 I Cceoma lumina'um. \ UMlago Maydit. 



