274 



PLANT DISEASES 



There is no excuse for any farmer having any of the 

 three smuts just mentioned, as he can kill them at the 

 cost of a very few cents an acre of grain. 



FIG. 140. Stinking Smut of Wheat. 



I, a head of wheat with smutted grains (smutted grains are colored black); 2, small portion 

 of a head showing smutted grains which are fissured, and show the black spore mass 

 within; 3, isolated grains which are smutted and have fissured walls. One grain is sec- 

 tioned; 4, smut spores germinated and producing at the end of the germ tube long, needle- 

 like spores, which sometimes fuse together in pairs by cross threads as shown on the left; 

 5, the thread spores, shown in 4, in germination sometimes again producing secondary 

 spores; 6, smut spores germinating to long infection threads without first forming spores. 

 4-6, highly magnified. (After Tubeuf.) 



2. Corn smut forms large, boil-like structures on the 

 leaves, ears, tassels, or any other part of the corn. These 

 boil-like structures develop into masses of powdery 

 material ; that is, the spores of the fungous plant. The 



