44 



T&E BUSTS OF GRAINS IN THE UNITED STATES. 



Table III. — Summary of experiments to determine the vitality of successive uredo genera- 

 tions of various grain rusts — Continued. 



PUCCINIA GRAMINIS HORDE! ON WHEAT FROM BARLEY— Continued. 



Original inoculation made Nov. 14, 1906. 



Original inoculation made Nov. 22, 1906. 



Date of inocu- 

 lation. 



Number 

 of leaves 

 inocu- 

 lated. 



Date 

 matured. 



Number 

 of leaves 

 pustuled. 



Date of inocu- 

 lation. 



Number 

 of leaves 

 inocu- 

 lated. 



Date 

 matured. 



Number 

 of leaves 

 pustuled. 



1907. 



Oct. 31 



Nov. 20 



Dec. 12 



1908. 



Jan. 25 



Feb. 15 



Mar. 3 



8 

 10 



10 



10 

 6 

 10 

 10 

 7 

 10 

 10 

 10 

 10 

 10 

 10 

 10 

 10 

 10 

 10 

 10 

 9 

 9 

 10 



10 



10 

 3 



10 

 10 

 10 

 10 

 8 

 10 

 10 

 10 

 10 

 10 

 10 



1907. 



Nov. 18 



Dec. 10 



1908. 

 Jan. 8 



Feb. 15 



Mar. 3 



Mar. 19 l 



Apr. 13 



Apr. 27 



May 13. 



May 26 



June 12 



June 25 



July 10 



Julv 28 



Aug. 12 



Sept. 1 



Sept. 17 



Oct. 2 



Oct. 24 



Nov. 6 



Nov. 20 



Dec. 12. 



1909. 

 Jan. 10 



Feb. 7 



Feb. 23 



Mar. 14 



Mar. 30. 



Apr. 12 



Apr. 27 



May 20 



June 14 



June 26 



July 7 



July 21 



Aug. 2 



( 3 ) 



8 

 10 



10 



4 



6 



10 

 9 



10 

 10 

 10 

 10 

 10 

 7 

 6 

 9 

 ( 2 ) 

 10 

 10 

 9 

 6 

 9 



9 



1 



1907. 



Oct. 31 



Nov. 20 



Dec. 12 



1908. 



Jan. 25 



Feb. 15 



Mar. 3... 



Mar. 30 



Apr. 13....... 



Apr. 27. 



May 13 



May 26 



June 12. 



June 25 



Julv 10 



July 28 



Aug. 12 



Sept. 1 



Sept. 17 



Oct. 2 



Oct. 24 



Nov. 6 



Nov. 20 



Dec. 12 



1909. 



Jan. 10 



9 



10 



10 



10 



10 

 10 

 10 



8 

 10 

 10 

 10 

 10 

 10 

 10 



6 

 10 



( 2 ) 



10 

 10 

 9 

 9 

 10 



10 



10 



8 

 10 

 10 

 10 



4 

 10 

 10 

 10 

 10 

 10 

 10 



1907. 



Nov. 18 



Dec. 10 



1908. 

 Jan. 8 



Feb. 15 



Mar. 3 



Mar. 19 * 



Apr. 13 



Apr. 27 



May 13 



May 26 



June 12. 



June 25 



Julv 10 



July 28. 



Aug. 12 



Sept. 1 



Sept. 17 



Oct. 2 



Oct. 24 



Nov. 6 



Nov. 20 



Dec. 12 



1909. 

 Jan. 10 



Feb. 7 



Feb. 23 



Mar. 14 



Mar. 30 



Apr. 12 



Apr. 27....... 



May 20 



June 14. 



June 26 



Julv 7 



July 21 



Aug. 2 



( 3 ) 



9 

 10 



10 



10 

 6 

 10 



Mar. 31 



Apr. 13 



Apr. 27 



May 13 



May 26 



June 12 



June 25 



July 10 



July 28 



Aug. 12 



Sept. 1 



Sept. 17 



Oct. 2 



Oct. 24 



Nov. 6 



Nov. 20 



Dec. 12 



9 



8 

 10 

 10 

 10 

 10 

 10 

 7 

 1 

 5 

 ( 2 ) 

 10 

 6 

 5 

 9 

 9 



8 



1909. 

 Jan. 10 



4 



Feb. 7 



3 Ffib. 7 



7 



Feb. 23 



Mar. 14 



Mar. 30 



Apr. 12 



Apr. 27 



May 20 



June 14 



June 26 



July 7 



10 

 10 



8 

 10 



8 

 10 

 10 

 10 

 10 

 10 



( 3 ) 



Feb. 23 



Mar. 14....... 



Mar. 30....... 



Apr. 12 



Apr. 27 



May 20 



June 14 



June 26 



July 7 



July 21 



Aug. 2 



8 

 10 



8 

 10 



4 

 10 

 10 

 10 

 10 



Julv 21 



Aug. 2 



10 



( 3 ) 







1 Series sent from Washington, D. C, to Minneapolis, Minn. 



2 Not recorded. 



3 Experiment discontinued. 



The lowered percentage of successful infections in July and August 

 of 1907 and 1908 is noticeable and was due to the extreme heat in 

 the greenhouses at the time of inoculation. The uredospore germi- 

 nates either not at all or not nearly so well at the excessive tempera- 

 tures of 90° to 100° F. and over, which then existed during parts of 

 each day, as it does in more moderate temperatures, 55° to 75° F.; 

 the germ tubes are injured and the host plants themselves become 

 drawn and weak, reducing the chances for infection very markedly. 

 Puccinia coronata, however, is noticeably resistant to heat and 

 P. rubigo-vera on wheat is a close second, while P. graminis on oats 

 is injured quickly and P. graminis on rye is killed by excessive tem- 

 peratures. 



216 



