208 



FUN'GI AlfD FUXGICIDES 



spores are the winter sjDores, and are very different in 

 structure and appearance from the summer spores. The 

 two kinds are produced from the same mycehum, and at 

 certain seasons they may be found intermingled in the 

 same mass, or pustule. This fungus usually only devel- 

 opes after the corn has gotten well along in its growth, 

 so that the effect of its injury is less than if the very 



FIG. 86. CORN KUSt. 



a, Section of leaf showing teleuto-spores ; h, uredo-spores; c, teleuto-spores. 



Magnified. 



young plants were attacked. Hence it seldom assumes 

 a serious economic importance. 



The brown summer spores (called by botanists uiedo- 

 spores) are nearly spherical, with the outer wall thickly 

 studded with minute pointed projections (Fig. 86 l). 

 They are about one-one thousandth of an inch in diam- 

 eter, and are borne on slender stalks arising from the 



