366 



Journal of Agricultural Research 



Vol. XIX. No. 8 



EXPERIMENTAL STUDIES 



EFFECT OF FORMALIN TREATMENT ON BACTERIUM TRANSLUCENS VAR. 

 UNDULOSUM SMITH, JONES, AND REDDY 



As the bacterial blackchaff disease has often been found together with 

 the covered smut of wheat in western fields, experiments were first per- 

 formed to determine whether the formalin treatment for smut would 

 at the same time control the blackchaff disease. Following the procedure 

 above outlined, sterilized wheat seeds were inoculated with virulent 

 isolations of the blackchaff organism and then treated for various 

 periods with formalin i to 200 and i to 400 (i part of 36.6 per cent 

 formalin to 200 or 400 parts sterile tap water) and finally dried and 

 planted on agar plates. The results of treatments of over 3,000 wheat 

 seeds in four experiments are summarized in Table I. 



Table I. — Effect of formalin treatment on blackchaff bacteria on wheat seeds 



Treatment. 



Percentage 

 contami- 

 nated with 

 fungi or 

 bacteria 

 other than 

 blackchaff. 



Formalin i : 200 overnight 



Formalin i : 400 for 3 hours 



Formalin i : 400 for 6 hours 



Formalin i : 400 for 12 hours 



Controls inoculated but not treated 



17.7 

 7-3 

 2,- 2, 



The data show that the blackchaff bacteria, dried on wheat seeds 

 as under natural conditions, can be held under control by the formalin 

 I to 400 treatment, especially when exposed for six hours or longer. 



Since all the formalin used in treating the seeds had evaporated 

 during the overnight drying, no residual solution could have been left 

 on the seeds in the plates to prevent bacterial growth. Neither did 

 24 to 48 hours' drying after inoculation kill the organisms, as was shown 

 by growth in the controls, which acted as an index of the viability of 

 the dried organisms as well as of the suitability for bacterial growth on 

 the part of the particular lot of media used. The conclusion is evident 

 that absence of blackchaff bacterial growth around treated seeds was 

 due only to the effect of the treatment. 



GREENHOUSE EXPERIMENTS WITH FORMALIN AND COPPER SULPHATE 

 EPKECT OP FORMALIN TREATMENT ON GERMINATION OP WHEAT SEED 



Parallel with the experiments made to determine the effect on the 

 bacteria, a series was carried out to determine the effect of the two 

 formalin solutions, as used above, on the germination of wheat seed. 

 The I to 200 strength formalin was not tried after the second test because 



