THE CONTROL OF CABBAGE BLACK-LEG. 



19 



Table VII. — Development of Naclc-leg in cahhage seed-l)ed plats sown with 2- 

 gram samples of treated seed at Madismi, Wis., in 1919. 





Length of 

 exposure. 



Eflect 

 upon 

 badly 

 infected 

 seeds- 

 viable 

 fungus 

 after 

 treat- 

 ment 

 (per 

 cent)." 



Eflect 



upon slightly infected commercial seeds. 





Lot 2-18. 



i 



Lot 3-18.6 



Type of treatment and tempera- 

 ture or concentration. 



Germi- 

 nation 

 (per 

 cent). 



Seed- 



hng 



injury, c 



Plants 

 infected 

 at the 

 end of 



the 

 experi- 

 ment 

 (per 

 cent). 



Germi- 

 nation 

 (per 

 cent). 



Seed- 

 ling 

 injury, c 



Plants 

 infected 

 at the 

 end of 



the 

 experi- 

 ment 

 (per 

 cent). 







75.3 

 16.6 

 12.0 

 15.3 

 '12.8 



"'2i.'7' 

 

 



92 

 92 



88 

 72 

 81 



92 

 70 

 73 

 46 



45 

 46 

 28 

 32 

 22 

 20 



83 

 81 

 86 

 85 

 81 

 67 

 52 

 59 

 34 

 11 



88 

 85 

 74 

 55 

 53 

 78 

 29 

 30 

 66 

 33 

 9 





 

 



e 

 e 







+ 



-t-+ 

 ++ 



++ 

 ++ 



++ 

 -t-+ 

 ++ 





 

 e 



29 

 16 

 62 

 22 

 12 



5 



1 

 

 2 



4 

 2 

 1 

 1 

 12 

 





 

 1 

 

 

 3 

 3 

 3 

 

 3 



19 

 31 

 13 



?' 



i 



1 

 

 3 

 2 

 3 



96 







7 



Mercuric chlorid: 



Strength 1 to 1,000 



30 minutes, 



rinsed. 

 30 minutes, 



rinsed. 

 30 minutes, 



un rinsed. 

 1 hour, 



rinsed. 



30 minutes 

 (30 minutes 



nhour 



[2 hours.... 



(1 minute.. 











Strength 1 to 500 















Formaldehyde, not rinsed after 

 treatment: 

 Strength 1 to 256 

















Strength 1 to 128 

















Hot, 1 to 128 formaldehyde: 









At 55°C 1 



h minutes . 

 (5 minutes . 

 (1 minute.. 





























Atecc 



■{2 minutes. 

 [5 minutes . 



[10 minutes 

 I20 minutes 

 )30 minutes 



1 hour 



5 minutes. 

 •{15 minutes 



30 minutes 



5 minutes. 

 ■^10 minutes 



15 minutes 



fl2 hours... 



24 hours... 

 •{48 hours... 



72 hours. . . 

 196 hours... 



12 hours... 

 -^24 hours... 



36 hours... 



12 hours... 

 ■^18 hours... 

 I24 hours... 



""6"' 

 20.0 

 4.0 

 



32.6 

 17.7 

 36.0 



9.0 





 25.0 



4.0 



4.1 



2.8 

























Hot water: 













































At SS^C 











- 



- 

















At 60° C 



+ 

 + 

















N- 









Dry heat: 



At 85°C 



92 

 98 

 69 

 74 

 78 

 93 

 63 

 57 

 79 



8 



e 



e 

 6 



7 

 24 

 6 



AtOO^C 





- 



.5 

 .5 



3 

 2 



AtOo'C 



+ 

 -1- 



? 



2 







h 



65 



e 







o Data summarized from Tables I to IV, lots Nos. 4-18 and 1-19. 



6 Wisconsin Hollander variety, grown in 1918. 



c Symbols used: 0= No injury; ©=sUght; H-=mediuin; +=severe; +4-=very severe. 



It is evident from these trials that complete disinfection of cab- 

 bage seed infected with Phoma lingam without material reduction 

 in germination is not to be hoped for. It is possible that some of the 

 stronger treatments may be used with certain lots of seed, but their 

 recommendation for general use is out of the question. Moreover, 

 it is unsafe to assume that treatment, even if carried to the point 

 where reduction in germination and seedling injury begins, can 



