1922.] 



Preventing " Bunt " in Wheat. 



725 



Table I. 



Treatment. 



Percentage 

 Germina- 

 tion. 

 98 



Number of Percentage 

 Bunted Ears of Bunted 

 per 1,000. Ears. 



Formalin 1 : 400 



Formalin 1 : 320 



9S 



$ 1} 0.5 

 <V> °l\ 0.35 



Formalin 1 : 480 



99 



(2) lu| °' 7 



(2) 62 $ bA 



( 1} 115 !■ U2 



(2) 171 ] 14 1 



Copper Sulphate 2.5 per cent. 



99 



Untreated 



99 



Discussion of Results, 1921. — In our previous article* we 

 recorded the fact that formalin diluted 1 : 820 (1 pint to 40 gal. 

 water) was as effective in controlling bunt as the 1 : 240 solution 

 (1 pint to 30 gal. water) and was therefore to be preferred. The 

 dilution 1 : 320 was the weakest used in all previous experiments ; 

 it was decided therefore to use in 1920-21, the weaker solutions 

 1 : 400 and 1 : 480, and contrast these with the solution pre- 

 viously used. 



As will be seen from Table I. all the formalin solutions gave 

 satisfactory results, reducing the percentage of " bunted " ears 

 from 14.2 to less than 1, the actual differences observed being 

 perhaps within the experimental error. Since it was clear that 

 the limit of dilution when formalin ceases to be effective had not 

 been reached, it was decided to carry out a further series of 

 experiments in the next year before publishing these results. 



The one copper sulphate solution that was used, of 2.5 per 

 cent, strength (2| lb. to 10 gal. water), was the strongest that 

 our previous experiments had shown could be used without 

 seriously injuring the germination of the seed. As is shown in 

 Table I, the control of bunt when using this copper sulphate 

 solution was by no means satisfactory; the 5 per cent, of 

 " bunted " ears that appeared in the plots would represent a 

 very serious infestation in the field. In the writers' opinion the 

 use of a copper sulphate solution, and also of the proprietary 

 articles containing copper sulphate which are sold as remedies 

 for bunt, should be abandoned in favour of formalin. 



II. Experiments during the season 1921-22. — The object of 

 these experiments was to test weaker solutions of formalin and 

 also to obtain some information relative to the effect that the 

 presence of whole bunted grains, in samples of seed-wheat 

 treated by the formalin method, might have on the amount of 

 bunt in the resulting crops. 



* This Journal, Vol. XXVII, 1921, p. 1013. 



