EPIDEMICS. 



63 



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

 1904 had the most rust. 



RELATIVE HUMIDITY. 



H the development of rust were in direct pro])ortion to the relative 

 humidity over the whole region, 1905 sliould 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).^ 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 ths 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. 



October 



November 



December 



January 



February 



March 



April 



May 



Jime , 



July 



Departure from normal: 



Accumulative 



Average monthly 



O f 3 crop montlis— 



Accumulative 



Average monthly. 



Of month containing 

 critical period 



Texas. 



+ 







4.9 

 1.1 

 _2 

 2^7 

 1.5 

 1.8 



2.4 

 .34 



6.0 

 2.0 



1.8 



Okla- 

 homa. 



5.3 

 2.3 

 1.4 

 2.1 

 .1 

 1.3 

 3.2 



-2.1 



- .3 



-4.4 



- 1.40 



-3.2 



Kan- 

 sas. 



+4.8 



-5.00 



+3.1 



-2.6 



+2.1 



- .3 



_ o 



+1.9 



+ .27 



+ 1.6 

 + .5 



Mis- 

 souri. 



+ 7.3 

 -2.4 

 + 1.1 





 + 4.8 

 + .4 







+11.2 



+ 1.6 



+ 5.2 

 + 1.7 



-5 



Ne- 

 bras- 

 ka. 



-4 



+ 6 

 -4 



+ 1 



+ 



Iowa. 



- 3.5 

 + 3.5 

 _ 2 



+ eio 



+ .3 

 1.2 ,+ 1.4 

 5 - 5.6 



South 

 Da- 

 kota. 



-7.7 1+ 2.5 

 -1.10+ .35 



-6. 10 - 3. 9 

 -2.03- 1.3 



+ 0.8 



-3.8 



+ 2.9 







- .5 



- 2.2 



- 2 



-4.8 



- .68 



- .47 



- 1.56 



5.6 



North 

 Da- 

 kota. 



+ 



2.7 



3.5 



4.5 



1.3 



3 



1.6 



1.3 



+ 2.4 

 + .34 



.10 

 .03 



- 1.13- 2.6 



Min- Wis- 

 nesota. consin. 



+ 



1.00 

 1.00 

 4.7 

 .7 

 .9 

 2.6 

 2.6 



.30 

 .04 



- 4. 



- 1. 



Aver- 

 age. 



+ 1.8 



+ .8 



+ 8.6 



+ .3 



+ 1.5 



- 4.1 

 -1.1 



+ 7.8 

 + 1.1 



- 3.7 



- 1.23- 



I 



- 1.10 



+0.85 

 + .12 



-2.21 

 - .73 



.26 



' Accurate detailed records of relative humidity for tius region during the years under consideration are 



>t av:lilahU>_ a.nH tjlhllln-tinnt; tiro thprpfnro rtiYiifforl 



not available, and tabulations are therefore omitted. 

 216 



