EPIDEMICS. 



63 



rust than either 1903 or 1904, while, as a matter of fact, the year 

 1904 had the most rust. 



RELATIVE HUMIDITY. 



If the development of rust were in direct proportion to the relative 

 humidity over the whole region, 1905 should have had more than 

 either 1903 or 1904, as the relative humidity during the month con- 

 taining the critical period averaged about normal in 1903, about 1§ 

 per cent above normal in 1904, and approximately 6 per cent above 

 normal in 1905 (78). 1 Of course a certain degree of humidity is 

 necessary for rust development, but an excess over this degree ap- 

 parently does not increase its virulence. 



TEMPERATURE. 



Table VII summarizes the temperature records for the several 

 periods in 1903, 1904, and 1905 in the important States of the wheat- 

 growing region. 



Table VII. — Temperature record, showing the average monthly departure (in degrees 

 Fahrenheit) from normal in several States in 1903, 1904, and 1905. 



1903. 



Month. 



Texas. 



Okla- 

 homa. 



Kan- 

 sas. 



Mis- 

 souri. 



Ne- 

 bras- 

 ka. 



Iowa. 



South 

 Da- 

 kota. 



North 

 Da- 

 kota. 



Min- 

 nesota. 



Wis- 

 consin. 



Aver- 

 age. 







 + 4.9 



- 1.1 



— 2 

























+ 5.3 

 -2.3 

 + 1.4 



+4.8 



-5.00 



+3.1 



-2.6 



+2.1 



- .3 



- .2 



+ 7.3 

 -2.4 

 + 1.1 





 + 4.8 

 + .4 























-4.6 

 +6.1 



-3.5 

 4- 3.5 















+ 0.8 



- 3.8 

 + 2.9 







- .5 



- 2.2 



- 2 



- 4.8 



- .68 



- .47 



- 1.56 



- 2 



+ 2.7 

 -3.5 

 + 4.5 

 + 1.3 

 + 3 

 -1.6 



- 1.3 



+ 2.4 

 + ■ .34 



+ .10 

 + .03 



- 1.13 



+ 1.00 



- 1.00 



+ 4.7 



- .7 

 + .9 

 -2.6 

 -2.6 



- .30 



- .04 



-4.5 

 -1.5 



-2.6 



+ 1.8 

 + .8 

 + 8.6 

 + .3 

 + 1.5 



- 4.1 



- 1.1 



+ 7.8 

 + 1.1 



-3.7 



- 1.23 



- 1.10 







- 2.7 1- 2.1 



- 1.5 + -1 



-4.7 - .2 

 + 1.6 +6.6 

 + .1 + .3 

 -1.2 + 1.4 

 -5 - 5.6 











- 1.8 



- 1.3 



- 3.2 















July 











Departure from normal: 



Accumulative 



Average monthly 



Of 3 crop months- 

 Accumulative 



Average monthly. 



Of month containing 



critical period 



-2.4 

 - .34 



-6.0 

 -2.0 



-1.8 



- 2.1 



- .3 



-4.4 



- 1.46 



-3.2 



+1.9 



+ .27 



+1.6 

 + .5 



- .2 



+11.2 



+ 1.6 



+ 5.2 

 + 1.7 







-7.7 + 2.5 

 -1.10+ .35 



-6.10- 3.9 

 -2.03- 1.3 



-5 - 5.6 



+0.85 

 + -12 



-2.21 

 -.73 



-2.26 











1904. 



















-2.3 



- .8 

 + .1 



- 1.1 

 + 5.4 

 + 5.9 

 -1.1 

























- 1.8 

 + .8 



- .9 

 + 5.6 

 + 5.9 

 -2.4 

 -1.6 



-0.1 

 + .1 



- .4 

 +2.6 

 +4.9 

 -4.9 

 -2.5 



- 2.0 



- 3.0 

 -2.6 



- .2 

 + 2.5 



- 6.4 

 -1.9 



















+ 1.3 

 + .1 

 +1.7 

 +4.3 

 -3.7 

 - .6 

 -2.8 



-3.9 

 -4.2 

 -4.8 

 + 2.4 



- 5.2 



- .8 

 -2.5 













January 



February 



March 



April 



-2.5 



- 5 

 + 3 

 -3.6 





 -2.4 

 -3.7 



-14.2 



- 2.02 



- 6.10 



- 2.03 



- 3.70 



- 3 



- 8.8 

 + 6.9 



- 4 

 + .8 

 -1.7 

 -3.6 



-13.4 



- 1.91 



- 4.50 



- 1.5 



-3.60 



-4.8 

 -8.3 

 + .1 



- 4.8 



- .6 

 -1.9 

 -3.6 



-23.9 



-3.42 



- 6.10 



- 2.03 



-3.60 



-6.9 



- 8.8 



- .8 



- 6 



- .4 

 -2.4 

 -3.4 



-28.7 

 -4.1 



- 6.20 



- 2.06 



- 3.40 











July 













Departure from normal: 



Accumulative 



Average monthly 



Of 3 crop months — 



Accumulative 



Average monthly. 



Of month containing 



critical period 



+ 6.1 



+ .87 



+ 10.2 



+ 3.4 



- 1.1 



+ 5.6 

 + .8 



+ 1.9 

 + .6 



-1.6 



- .30 



- .04 



-2.5 



- .8 



-2.5 



-13.6 

 -1.9 



- 5.8 

 -1.9 



-1.9 



+ .3 

 + .04 



-3.77 

 -1.25 



-2.8 



-19 

 -2.7 



-8.5 

 - 2.8 



-2.5 



-8.67 

 -1.23 



-3.11 

 -1.03 



-2.67 



i Accurate detailed records of relative humidity for this region during the years under consideration are 

 not available, and tabulations are therefore omitted. 

 216 



