FOOT-ROT DISEASES OF WHEAT IN AMERICA 5 
As yet the disease has not been found in the hard spring-wheat 
belt of the United States. Fraser (24), however, in 1923 found the 
disease severe in one field of Marquis (spring) wheat in Saskatche- 
wan, Canada. Davis® found Marquis susceptible to infection by 
Ophiobolus graminis. We also found that this variety became 
badly infected when sown in infested soil in the spring out of doors 
at Madison, Wis. These plats were inoculated with a pure culture 
of the parasite the previous fall and subjected to outside conditions 
during the entire winter. It is evident, therefore, that take-all will 
develop in the spring-wheat region if the fungus is present. 
Although the take-all infested areas occurring in this country 
are relatively small, it is important to note that as infection centers 
they are located at rather strategic points. The disease seems to 
Fic. 1.—Outline map of the United States, showing locations, indicated by dots, where 
wheat take-all has been found 
have a firm hold in the center of the hard winter-wheat belt, and 
observations show that it is steadily spreading. 
ECONOMIC IMPORTANCE 
Take-all is capable of causing great losses in the United States by 
knlling the plants outright or by producing badly shriveled grain. 
In fields where the disease is abundant it prevents successful wheat 
erowing. In some regions it has not been uncommon to find fields 
where it caused a decrease of 50 to 60 per cent of the grain crop, 
and greater losses frequently occur. In this connection, H. P. 
Barss reported to the Office of Plant-Disease Survey that in 1921 
he observed 50 acres of wheat in Oregon in which 10 acres were 
entirely destroyed by this disease and 20 acres were hardly worth 
harvesting. On the other hand, many of the infested fields observed 
have shown only a relatively small amount of infection, and owing 
® Davis, R. J. Studies on Ophiobolus graminis Sacc. and the Take-All Disease of Wheat. 
(Unpublished manuscript.) 
