74 AGRICULTURE 



is seldom destroyed, only a few of the glumes being af- 

 fected. Scab results in a shrinkage of the kernels, and 

 hence a reduction in the yield and an injury of the quality 

 of the wheat. No cure has yet been discovered for wheat 

 scab. A second crop of wheat should not follow wheat 

 that has been affected with scab. If this is necessary, how- 

 ever, the stubble of the first crop should be burned to de- 

 stroy as much of the scab as possible. 



Rust in wheat. Rust is one of the most serious en- 

 emies of the wheat crop. It is nearly always present in 

 some degree, and has at times almost wholly destroyed the 

 crop over considerable areas. There are two kinds of 

 rust, one attacking the leaves and the other the stems of 

 the plants. The stem rust is much more destructive than 

 the leaf rust. 



Rust may in some cases live over winter on the old 

 plants, and be ready to attack the new crop if wheat is 

 again planted .on the field. Wheat rust also lives on other 

 plants, especially the barberry, and is spread from them by 

 birds or insects to wheat-fields. Laws have been passed in 

 some states requiring the destruction of barberry hedges 

 because of their part in spreading rust. 



Moist seasons are more favorable to the ravages of 

 rust than dry. Rust results in weakening the stem of the 

 wheat plant, and reducing the size and quality of the grain. 

 In some cases the heads even fail to fill, and the crop is a 

 total failure. There is no known cure for rust, though cer- 

 tain varieties of wheat are better able to resist it than 

 others. The earlier varieties are usually safer than the 

 later. 



Smut in wheat. There are two kinds of smut that 

 attack the wheat plant, loose smut and stinking smut. Loose 

 smut usually destroys both the glumes and the kernels, leav- 

 ing only the bare stem. Stinking smut grows inside the 



