6 BULLETIN" 618, U. S. DEPARTMENT OP AGRICULTURE. 
Plains. An apparent exception to this high-yielding power under 
drought conditions was noted at several stations in the two very dry 
years, 1910 and 1911. In these years the durum wheats produced 
relatively low yields. This was found to be due, however, not to 
lack of drought resistance, but to sterility caused by a combination 
of climatic conditions, including drought and hot winds coincident 
with the flowering period of durum wheat. The floral organs were 
injured, and the kernels did not develop, much reducing the yields. 
On some of the same stations durum wheat which was sown later in 
the spring and had not reached the flowering stage at the time hot 
winds occurred was not injured, although exposed to all the other 
drought conditions. 
Many varieties of durum wheat are somewhat resistant, and cer- 
tain varieties very resistant, to attacks of stem rust (Puccinia gram- 
inis Pers.). The varieties now grown commercially are subject to 
more or less infection on the sheaths and leaves, while the peduncle, 
or neck, often remains fairly free from such infection. This allows 
the development of a fairly plump kernel under rust conditions which 
cause serious injury to the common wheats. 
The durum wheats also are less subject to smut than the spring 
common wheats. Bunt, or stinking smut (TiTletia foetens (B. and C.) 
Trel. and T. tritici (Beij.) Wint.), rarely affects durum wheat, al- 
though the loose smut (Ustilago tritici (Pers.) Host.) occurs about as 
frequently on durum as on common wheats. 
There are some objections to the growing of durum wheat, wholly 
apart from market considerations. The long stiff beards are such a 
source of discomfort in handling the crop that many farmers object 
to growing it on that account. However, the increasing use of ma- 
chinery in harvesting and thrashing is gradually removing this objec- 
tion. The spike or head in the durum wheats is so compact that it 
dries very slowly after rains or heavy dews. This makes the durum 
varieties susceptible to the attacks of scab (Fusarium culmorum 
(W. Sm.) Sacc.) and other imperfect fungi. These fungi sometimes 
affect durum wheat rather seriously. 
The durum wheats have come from countries of low rainfall and 
fairly high summer temperatures, where loss of moisture by evapo- 
ration is rapid. The results of many experiments show them to be 
valuable under similar conditions in the northern Great Plains in 
this country. On account of their ability to produce well in the 
presence of rust infection, they also are valuable and widely grown 
in the subhumid portions of the Dakotas and western Minnesota. 
PRODUCTION. 
The varieties of durum wheat introduced by the United States 
Department of Agriculture in the years 1898 to 1900 were distributed 
to farmers as well as to experiment stations. The new introductions 
soon became popular among farmers of the northern Great Plains. 
