1922.] 



Preventing " Bunt " in Wheat. 



727 



the seed had none, it is to be assumed that the presence of such 

 grains did not increase the amount of infection; the plots of 

 which the seed received similar treatment are therefore taken 

 together in calculating the percentage of bunt resulting from 

 each treatment. 



Table II. 



Whole Bunted ■ 





Grains absent 





Bunted 



Percentage 



Treatment. 



or present (2 



Percentage 



Ear* per 



q Bunted 





'per cent,') in 



(n'erm motion. 



L00O. 



Ears. 





the seed. 







Formalin 1 : 320 



... (1) Absent 



98 







0.05 





(2) Present 



100 



1 





Formalin 1 : 480 



... (1) Absent 



99 







0.05 





(2) Present 



99 



1 





Formalin 1 : (340 



... (1) Absent 



100 



7 



0.65 





(2) Present 



98 



6 





Formalin 1 : 800 



... (1) Absent 



99 



17 



1.4 





(2) Present 



100 



11 





Untreated 



... (1) Absent 



97 



409 



38.95 





(2) Present 



100 



370 





Discussion of Results, 1922. — The formalin solutions were 

 used at the following dilutions : 1 pint of formalin to 

 respectively 40. 60, 80 and 100 gal. of water. The results 

 obtained, shown in Table II, showed clearly that the formalin 

 became less efficacious the more it was diluted below the 1 : 480 

 (1 pint to 60 gal.) limit. The presence of 2 per cent, of whole 

 " bunted " grains in the seed produced no increase of disease. 

 The artificially contaminated seed produced in the two " con- 

 trol " plots as high a percentage of " bunted " ears as 37 and 

 40. In view of the intensity of the disease present its reduction 

 to 1.4 per cent, in the plots where the formalin was used at the 

 extreme dilution of 1 : 800 (1 pint to 100 gal.) is noteworthy, as 

 indicating the efficacy of formalin as a fungicide against bunt. 

 The results show that the use of formalin, diluted 1 : 480 (1 pint 

 to 60 gal.) gives a perfectly satisfactory control of bunt. With 

 formalin at this dilution no possible injury to the seed -wheat is 

 to be feared, provided that it is applied in the method described 

 below. 



Summary. — 1. The old traditional method of "pickling" 

 wheat with a solution of " bluestone " (copper sulphate) should 

 be abandoned. Experiments have shown that a solution of the 

 strength necessary to kill the spores of bunt seriously injures the 

 germination of the seed-wheat. 



