142 FIELD CROP PRODUCTION 



account of limited time, must gain his knowledge by care- 

 ful study. This study should be such as to enable him 

 to quickly see in a sample both the good and bad points, 

 and with both in view to arrive at an accurate decision. 

 By carefully analyzing several samples, especially pre- 

 pared for the purpose, experience will be gained that will 

 enable the student to analyze more easily any sample, 

 without making the actual separations. 



FUNGOUS DISEASES AND INSECT ENEMIES 



129. Fungous Diseases. — Wheat is attacked by three 

 important and several minor fungous diseases. The most im- 

 portant are the smuts. There are two kinds, namely, the loose 

 and the stinking smuts. The loose smut, while it is widely 

 spread, is not as destructive as the stinking smut. In the field, 

 the loose smut is easily recognized, since it has converted the 

 heads into black, powdery masses before they appear above 

 the leaf sheath. The spores are soon blown away by the wind 

 and only the naked stem remains at harvest time. It may be 

 controlled bj- a hot water treatment of the seed, but this treat- 

 ment is rather unsatisfactory and is not generally practiced. 



The stinking smut is not so readily recognized in the field, but 

 at thrashing time the presence of the dusty, ill-smelling spores 

 indicates its presence. If a grain of wheat affected by the stink- 

 ing smut be cut open, it will be found to contain no endosperm, 

 but in its place the black, stinking spores. Methods for its 

 treatment have been given elsewhere. (See page 132.) 



The rusts of wheat occasionally damage the crop to a con- 

 siderable extent. They are recognized by the rusty brown and 

 black spores that attack the stem and leaves of the plant during 

 any stage of its growth. The damage done by rusts depends to a 

 considerable e.xtent upon weather conditions. Some seasons the 

 damage may be little, while in favorable years for its growth the 

 crop may be almost entirely ruined. There is no effective remedy 

 for the control of the rusts. 



The scab attacks the glumes of the plant, and is widely dis- 

 tributed. It seldom causes serious loss, although occasionally 

 much shriveled wheat results from its ravages. 



