n. P I.— 66.5. 



THE RUSTS OF GRAINS IN THE UXITEU ST.VTES. 



INTRODUCTION. 



That rusts are among the most serious diseases of grains in the 

 United States is generally granted. As they are always present 

 in humid grain-grow-ing districts to a greater or less extent, it is 

 almost impossible to inake accurate estimates of the damage caused 

 by them. Estimates are, perhaps, more often too low than too 

 high, so that the losses of fifteen to twenty million dollars annually, 

 estimated by Bolley (28,^ p. 615) for the United States, certainly 

 seem within reason. Numerous references to losses from rust epi- 

 demics in different countries may be found. 



The most severe epidemic in the last decade occurred in the 

 United States in 1904. It was particularly prevalent in the spring- 

 wheat belt of the northern Mississippi Valley, where the three States, 

 Mnnesota, South Dakota, and North Dakota, in wliich the bulk 

 of the hard spring wheat of the United States is raised, suffered per- 

 haps more than any other section of the country. Table I shows a 

 comparison of the wheat crop in these three States for the years 1903, 

 1904, and 1905, affording a basis for an estimate of the losses sus- 

 tained in this epidemic. 



Table I. — Wfmit crop in Minnesota, South Dakota, and A^orth Dakota in 190.3, 1904, 



and 1905* 



* Compiled from U. S. Crop Report. 



Average yield per acre for 1901? and 1905 = 13.4 bushel.'*; for 1904 = 11.65 bu.>^hels. 

 Reduction in yield per acre in 1904 below the average for 1903 and 1905=1.75 bushels. 

 Total reduction in yield in 1904=13,193,695 (acres) X 1.75=23,088,966 (bushels). 

 Average price for the three States for 1903 and 1905=66.8 cents. Reduction in value 

 in 1904 below the average for 1903 and 1905=23,088,966X66.8 cents=$15,423,429.28. 



1 The serial nimibers in parentheses throughout this bulletin refer to the titles in the " Bibliography" on 

 pages 79-82. 



216 7 



