48 BULLETIN 1074, U. S. DEPARTMENT OF AGRICULTURE. 



MILLING AND BREAD MAKING. 



Next to productivity, the value of wheat varieties for milling and 

 bread making probably is of the greatest economic importance, as 

 this is the principal use for wheat. There are significant differences 

 in milling and bread-making values of different varieties. As in 

 yield, these differences can be accurately determined only by careful 

 experiments, identically conducted with comparable samples. Pre- 

 vious authors have not used these differences in distinguishing varie- 

 ties. Where definite experiments have shown certain varieties to be 

 unusually good or poor for milling or bread making, these differences 

 are here pointed out, following the description. 



RESISTANCE TO LOW TEMPERATURE. 



Hardiness or resistance to low temperatures consists of both the 

 ability to survive low winter temperature and resistance to injury 

 from spring and summer frosts. Very little is known concerning the 

 latter character. The winter hardiness of several varieties was re- 

 corded for three years by Eriksson (88) and the hardiness of many 

 varieties was given by Koernicke and Werner (133). Following the 

 descriptions here given, the writers have indicated a few varieties 

 which are known to be especially winter hardy, but otherwise the 

 character is not mentioned. 



RESISTANCE TO DISEASES. 



Wheat varieties are known which have more or less resistance to 

 each of the various diseases of wheat. Practically all varieties of 

 wheat have been grown in nurseries where they were infected either 

 naturally or artificially, so as to be able to observe any marked re- 

 sistance to stem rust (Pwcdnia graminis), leaf rust (P. triticina), 

 stripe rust (P. glumarum), and bunt or stinking smut (Tilletia tritici 

 and T. foetens). The presence of resistance can be determined only 

 when all varieties have been equally exposed to all strains of a dis- 

 ease under conditions favorable for their development. A few varie- 

 ties have shown a distinct resistance to stem rust or to bunt, and this 

 fact is noted following their descriptions. 



CLASSIFICATION OF THE GENUS TRITICUM. 



•Wheat belongs to the grass family, Poaceae (Graminese), and to 

 the tribe called Hordese, in which the 1 to 8 flowered spikelets are 

 sessile and alternate on opposite sides of the rachis, forming a true 

 spike. Wheat is located in the subtribe Triticese and in the genus 

 Triticum, where the solitary 2 to many flowered spikelets are placed 

 side wise against the curved channeled joints of the rachis. 



There are two sections of the genus Triticum, one including the 

 old genus Aegilops, in which the glumes are flat or rounded on the 



