450 



The Control of Onion Smut. 



[Aug., 



as a whole looked much healthier and greener, and was altogether 

 more vigorous. 



The garden was again visited by the Inspector on Nov. I4th, 

 when no disease was present either on the treated or untreated 

 portions. The estimated crop on the treated area was 10,000 

 hunches, a fair average for such a ci'op being 12,000 bunches. 

 On the control portion not more than a quarter of a crop existed. 

 It is believed that if wet weather had not followed immediately 

 after sowing, the formaldehyde treatment would have been even 

 more effective. 



The experiments are being continued by the Ministry. 



Summary. — From the above experiments it is clear that the 

 most efi'ective treatment against Onion Smut is undoubtedly the 

 application of formaldehyde to the open drill, the spores of the 

 fungus present in the soil being prevented from infecting the 

 germinating seed, either because they are killed or are tem- 

 porarily paralysed. That the latter may be the more likely 

 reason is indicated by the failure of the 1915 trial, when appli- 

 cation of a much stronger solution a fortnight before sowing 

 proved ineffective. In the United States the application is made 

 liy means of a receptacle attached between the handles of the 

 drill. The solution is fed into the drill from an open pipe whicli 

 is sufficiently long to prevent splasViing of the liquid. Further 

 search for resistant varieties will probably be repaid. 



The writer desires to express his thanks to Mr. John 

 Mordue, of W,ylam-on-Tvne for placing land and labour at his 

 'dispos'-^l. and to Mr. ¥red Dawson for the care he has taken in 

 •carryin*^ out th'^ trials. 



