210 Seed-borne Diseases of Cereals. [june, 



With the exception of one series, all the experiments were 

 made in a gas-heated sterilising oven, ventilated and kept at 

 a constant temperature. In the first experiment, small lots 

 of infected kernels of Kubanka durum wheat and Chevalier 

 barley were exposed to ioo° or no ° C. in the gas oven for 15 -hour 

 and 30-hour periods. A series of culture experiments were 

 made on the treated seeds to compare them with the untreated. 

 In most cases, Gihherella, Fusarium, Helminthosporium and 

 Alternaria developed from the unheated kernels of wheat and 

 barley, as well as from kernels that were heated for 15 hours. 

 From the kernels heated for 30 hours, however, only two yielded 

 fungus growth. 



For the second experiment, various grains were treated in 

 a large electrically-heated drying oven at a temperature of 

 about 100° C. in order to test the effect of 15 -hour and 30-hour 

 exposures on germinability. Samples of treated and un- 

 treated kernels were then sown in sand in the greenhouse. 

 The results showed that good dry seed of barley, wheat, oats 

 and rye was able to withstand this high temperature up to 

 30 hours. Previous tests had shown this time and temperature 

 to be fatal even to the persistent parasites. 



In the third experiment, only seeds known to be infected 

 with various diseases were used. The temperature averaged 

 100° C. for 30 hours. Samples of the treated and untreated 

 seeds were sown. The result showed that the barley was 

 not killed and that there was perfect control of the diseases, 

 while the untreated seed was heavily infected. 



In a fourth test, wheat, oats and rye were submitted to a 

 temperature of about 100^ C, and were found capable of with- 

 standing this severe drying process, though with certain samples 

 the germination was seriously reduced. 



Field sowings of aU the seed lots of the barley, wheat, rye 

 and oats treated in experiments 3 and 4 were made on 

 an isolated place on the University farm. Care was taken to 

 avoid contamination of seed from any source. The results were, 

 on the whole, satisfactory. Not only could the bacterial blight 

 of barley and oats be controlled by the dry-heat treatment, 

 but there was also a likelihood that it would prove efiicient 

 in controlling the " blackchaff " of wheat. AppHed to wheat 

 infected with " scab," the treatment also pointed to the 

 possibiHty of eliminating seed infection. Further, spot 

 blotch " and " netblotch " in barley were partially eliminated 

 by the treatment, which also diminished the percentage of 

 loose smut infection in both barley and oats. 



