NEMATODE DISEASE OF WHEAT. 



23 



Table III.— Effect of hot-water treatment on active larvae of the wheat nematode 



taken from galls. 





Number 

 of lots of 

 larvae 

 of about 

 300 each. 



Hot-water treatment. 



Extent 

 of obser- 

 vation 

 (days) 



Larvae living (per cent). 



Experiment. 



Date. 



Temper- 

 ature 



CO.), 



Dura- 

 tion. 



By lots. 



Average, 

 by treat- 

 ments. 





1 



2 



No. 9 ... 



1 

 1 

 1 

 1 

 1 

 1 

 1 

 2 

 2 

 2 

 1 

 1 

 1 

 2 

 2 

 1 

 2 

 2 

 1 

 1 

 2 

 2 

 1 

 1 

 2 

 2 

 1 

 1 

 2 

 2 

 1 

 1 

 1 

 2 

 2 

 1 

 1 

 2 

 2 

 1 

 1 

 2 

 2 



2 



Mar., 27 

 ...do 

 ...do , 

 ...do 

 ...do 

 ...do 

 ...do 



Mar. 26 



48 

 48 

 48 

 49 

 49 

 49 

 50 

 50 



Ifinutes. 



3 



5 



6 



3 



6 



10 



3 



5 



5 



5 



6 



10 



10 



10 



10 



15 



15 



15 



20 



3 



3 



3 



6 



6 



6 



6 



10 



10 



10 



10 



15 



3 



3 



3 



3 



6 



6 



6 



6 



10 

 10 

 10 

 10 

 Days. 



4 



4 

 4 

 4 

 4 

 4 

 4 

 4 

 4 

 4 

 4 

 4 

 4 

 6 

 4 

 4 

 6 

 4 

 4 

 6 

 4 

 4 

 4 

 4 

 6 

 4 

 4 

 4 

 6 

 4 

 4 

 6 

 4 

 6 

 4 

 4 

 4 

 6 

 4 

 4 

 4 

 6 

 4 

 4 



1 1 



85 

 90 

 50 

 90 

 50 

 20 

 75 

 50 

 .6 



3 

 15 



5 





























 20 



2 



2 



1 







2 

































 10 



1 





 

 .16 

 

 

 

 

 



95 

 95 

 95 





•85 



No. 10 





90 



No. 11 





50 



No. 6 





90 



No. 7 





"50 



No. 8 





20 



No. 3 





75 



No. 1-2 



eo 



4 

 1.5 



j- 19.7 



No. 27-28 



Apr. 29 i 50 



No. 45-46 



May 7 

 Mar. 27 

 ...do 

 Apr. 15 

 Apr. 29 

 May 7 

 Apr. 15 

 Apr. 29 

 May 7 

 Apr. 15 

 Mar. 27 

 Apr. 30 



50 

 50 

 50 

 50 

 50 

 50 

 50 

 50 

 50 

 50 

 51 

 51 



No. 4 



15 



No. 5 





1 



No. 18 





8 

 f 



No. 29-30 





 



No. 47-48 



No. 19 



1 



No. 31-32 





 



\ o 



No. 49-50 



| 



No. 20 







No. 12 





1 



No. 33-34. 



4 

 1 



]■ 5.8 



No. 51-52 



No. 13 .- . 



May 7 1 51 

 Mar. 27 : 51 

 Apr. 15 , 51 

 Apr. 30 1 51 

 Mav 7 : 51 

 Mar. 27 ; 51 

 Apr. 15 51 



i 

 1 



No. 21 







No. 3.5-36 



1 

 



1 ' 7 



No. 53-54 



J 



No. 14 



1 



No. 22 







No. 37-38 



Apr. 30 

 May 7 

 Apr. 15 

 Mar. 27 

 Apr. 15 

 Apr. 30 

 May 7 

 Mar. 27 

 Apr. 15 

 Apr. 30 

 May 7 

 Mar. 27 

 Apr. 15 

 Apr. 30 

 May 7 



[Mar. 27 

 {Apr. 29 



[May 7 



51 

 51 

 51 

 52 

 52 

 52 

 52 

 52 

 52 

 52 

 52 

 52 

 52 

 52 

 52 











n 

 



No. 55-56 



No. 23 



1 











] 



No. 24 







No. 39-40 



1 



.6 



> 2.2 





j 



No. 16 



1 



No. 25 





■„ 



No. 41-42 



2 







.3 



No. 59-60 



J 



No. 17 



1 



No. 26 







No. 43-44 





 



95 

 95 

 95 



n 

 



No. 61-62.. j 



1 



Cheek. 



I 95 







1 Room temperature. 



It is to be noted that neither the submersions at 48° nor 49° C. 

 were of sufficient duration to kill all the larvae, even though the 

 number remaining alive was somewhat below that of the untreated 

 lots held as a check. Treatments with water at 50° to 52° C. gave 

 uniform results; that is, the percentage of larvae surviving varied 

 directly with the length of immersion. For example, at 50° C., 19.7, 

 15, and 0.8 per cent survived after exposures of 5, 6, and 10 minutes, 

 respectively, while none lived where the exposure lasted for 15 min- 

 utes. Comparable results were obtained at higher temperatures, 

 with all larvae succumbing at 51° and 52° C. in 10 minutes. It is 

 interesting to note that the minimum length of time required to kill 



