696 Journal of Agriculture, Victoria. [11 iN'ov., 1918. 



in South Australia had carried out important investigations, and the 

 present Conference had been summoned to consider what further in- 

 vestigations were necessary, and by whom they should be carried out and 

 financed, with a view to avoiding unnecessary duplication of effort. 

 It appeared that the necessary work might be broadly divided into 

 two : — Experiments on n large scale for the treatment of wheat already 

 in store, such as were being conducted in South Australia; and more 

 fundamental scientific researches on the life-history of grain pests and 

 other matters bearing on the problem. 



After discussion it was decided that the press should not be admitted 

 to the Conference. 



Mr. EossELL (Chairman of the Special Committee of the Advisory 

 Council) outlined the researches that the Committee thought should be 

 undertaken. He emphasized the necessity for the employment of 

 research workers who would be able to give their whole time. A central 

 committee to co-ordinate all work carried out in Australia would obvi- 

 ously be a great advantage. 



Mr. Froggatt gave a review of the various pests which were damag- 

 ing the wheat, and emphasized the seriousness of the position. lie 

 considered that the necessary researches would require the employment 

 of a bio-chemist and entomologist. 



Dr. Hargreaves stated that, about a year ago, the position in 

 8outh Australia having become acute, the Government referred the matter 

 to the Department of Chemistry, and a Wheat Weevil Committee had 

 been appointed, of which he was chairman. The first experiments car- 

 ried out were as to the possibility of poisoning by gases. Hydro- 

 cyanic acid, carbon 'bisulphide, carbon monoxide, and carbon dioxide 

 had been tried, and of these carbon bisulphide was probably the most 

 efficient poison gas, though it had later been found that weevil could 

 be asphyxiated by the use of carbon dioxide. Treatment with lime 

 as advocated by Mr. Barrett had also been tried, but was found in- 

 efficient. Storage in sand was satisfactory on a small scale, but not 

 so good on a large scale. The heat treatment was then tried, and 

 seemed promising. A machine was designed and constructed in the 

 Department, and proved successful and economical. In connexion with 

 the heat treatment, over 2,000 experiments had been undertaken to de- 

 termine the rate of flow of wheat and the rate of heating in pipes of 

 various temperatures. The conclusion had been reached that most 

 heating machines work at too high an initial temperature, and that the 

 pressure of steam is too great. The South Australian machine works 

 at atmospheric pressure. It was realized, however, that heat treat- 

 ment was not a solution of the whole difficulty, as it was impossible 

 to treat all the affected wheat in time. Some experiments made by 

 Mr. Spafford had then suggested another alternative. He had sealed 

 up weevily wheat in bottles and found that the weevils died in a fort- 

 night. In three bottles it was found that the weevils were alive, but 

 this was traced to incomplete sealing. Variations in atmospheric pres- 

 sure probably accounted for the fact that the weevils were able to live, 

 as air would be forced into the bottles. After five days in a sealed 

 tube the percentage of carbon dioxide was found to be 15 per cent., 

 and this was sufficient to kill weevils. These experiments suggested 

 the possibility of enclosing stacks with a covering of malthoid, m.aking 

 them as airtight as possible, and then pumping in carbon dioxide. 



