DISEASES OF WHEAT 155 



only factor to be considered in determining the relative harm- 

 fulness of the species. The dove, the sparrow and the crow 

 also eat grain from the fields, as do many other species. None 

 of these birds are, however, entirely harmful; indeed the good 

 that many of them do by destroying injurious insects and seeds 

 more than counterbalances the damage occasioned by the eating 

 of grain. At least 50 different birds act as weed destroyers and 

 help to eradicate nearly 100 species of noxious plants. The 

 number of weed seeds eaten is enormous, one bird eating a 

 thousand seeds of some kinds for a single breakfast. The in- 

 sects eaten by these birds are also generally noxious. There is 

 usually an equilibrium of organisms in nature, and birds be- 

 come harmful only when they disturb this proper balance by 

 increasing out of proportion to their environment. 



"Yellow Berry." This occurs in hard winter wheat. Some 

 of the wheat berries are often lighter in color and weight than 

 the hard red ones, and also have a lower gluten content. Over- 

 ripeness and failure to stack the sheaves have been given as 

 causes, but opinions seem to differ as to this. It is claimed 

 that the annual loss in Nebraska is from one-half to one mil- 

 lion dollars. 1 



FUNGOUS ENEMIES 



"Glume Spot." This fungus receives its name from the 

 dark spots that it causes upon the glumes of wheat. It has 

 been studied but little, and no remedy is known. 



Wheat Scab (Fusarium culmorum) also attacks the glumes 

 and causes lead-brown-colored sections in the spike, or even de- 

 stroys the spike entirely. The loss is usually light, but may 

 reach a maximum of about 15 per cent. The only remedy sug- 

 gested is the burning of the stubble. 



Smut. Two kinds of smut attack wheat, stinking smut, or 

 bunt (Tilletia tritici (Bjerk.) Wint.), and loose smut (Ustilago 

 tritici (Pers.) Jens.). The enormous damage resulting from 

 this disease attracted attention in ancient Greece and Rome. 

 Hartlib called attention to the fact that smutty seed produces 

 smutty grain, and he was perhaps first to record a remedy 

 (1655). His three remedies for smut in wheat were liming the 

 1 Neb. Bui. 89 (1905), p. 50. 



