8 



BULLETIN 1029, U. S. DEPARTMENT OF AGEICULTUEE. 



increase in length of formaldehyde treatment. Injury to the seedlings 

 is evident first from delayed germination and later from various 

 degrees of retardation of growth. A slight check at the outset may 

 be overcome within a few days, but increase in the severity of 

 treatment results in permanent stunting. Accompanying the latter 

 there is usually definite injury to the cotyledons, which remain 

 dwarfed and become distorted in shape. Oftentimes with milder 

 treatments this injury is confined to that cotyledon adjacent to the 

 seed coat, while the other develops normally. 



Table II.- 



-Effect of formaldehyde solution upon the black-leg fungus within in- 

 fected cabbage seeds and upo'n commercial seeds. 





Length 

 of time 

 in the 

 solu- 

 tion 

 (min- 

 utes). 



Subsequent 

 treatment. 



Effect upon infected seeds. 



Effect upon com- 

 mercial seeds. 



Strength and temperature of 

 solution. 



Seed 

 lot. 



Num- 

 ber of 

 seeds 

 used. 



Seeds 

 with 

 viable 

 fungus 

 after 

 treat- 

 ment 

 (per 

 cent). 



Seeds 



with 



viable 



fungus 



and 

 germin- 

 ating 

 (per 

 cent). 



Germina- 

 tion (per 

 cent).. 



Seed 



ling 



in- 



jury.ft 





Seed 



lot 



2-18.0 



Seed 



lot 



3-18.a 



TJntreated 







4-18 

 1-19 

 1-19 

 4-18 



4-18 

 4-18 

 1-19 

 1-19 

 4-18 

 4-18 

 4-18 

 1-19 

 4-18 



130 

 24 

 10 



24 



25 

 25 

 15 

 23 

 25 

 25 

 25 

 24 

 25 



75.3 

 66.6 

 50.0 



33.3 

 16.0 

 16.0 

 60.0 

 . 13.0 

 24.0 

 16.0 







8.3 







22.3 

 

 10.0 





 



8.0 

 13.3 

 



4.0 

 4.0 

 

 

 



93 



97 



O 



Strength 1 to 2.56 







At room temperature 



30 

 37 



15 



30 



30 



30 



45 



60 



60 



120 



120 



1 



2 



5 



1 



2 



5 



Rinsed 



...do 



...do 



...do 



...do 



TJnrinsed . 



Rinsed 



...do 



TJnrinsed . 



Rinsed 



TJnrinsed - 

 do 









Do 



92 

 90 

 85 



98 





Strength 1 to 128: 



At room temperature 



O 



o 



Do 



e 



Do 



Do 



66 

 79 

 78 

 57 

 48 

 46 

 45 

 46 

 28 

 32 

 22 

 20 



80 



85 

 88 

 69 







+ 



Do 





Do 



+ 



Do 



++ 



Do 



++ 



Do 



++ 



At55°C 



4-+ 



Do 



.do 











-I-+ 



Do 



...do 











-t-+ 



At60°C.. . 



.do 











-f+ 



Do 



...do 











-f-(- 



Do 



do 











-I--I- 

















o Wisconsin Hollander variety grown at Racine, Wis., in 1918. 



!> Symbols used: 0= No injury; ©=slight; -h=medium; -|-=severe; ++= very severe. 



Table II shows that severe injury with 1 : 128 formaldehyde solution 

 resulted with one hour of treatment when the seed was subsequently 

 rinsed and with 30 minutes when the seed was dried without rinsing. 

 It is also shown that, although materially reduced, the fungus had not 

 been completely eradicated from infected seeds hj either of these treat- 

 ments. Complete disinfection was not attained with rinsed seed even 

 after two hours of treatment and only after one hour with unrinsed 

 seed. It is worthy of note that the infected seeds were killed some- 

 what earlier than the invading fungus, and this in practice might 

 reduce somewhat the number of jjrimary infections. It will be shown 

 later, however, that infected seeds although incapable of germination 



