Gov't Agricultural Experiment Station for North Dakota, pp. 26-28 (Jan 1891)

The hot water treatment

In 1888 J. L. Jensen of Denmark, called attention to the fact that immersing the seed of grain a few minutes (five) in water at a temperature of 133° Fahr. results in the destruction of the smut spores without injury to the seed. This has proved to be a most valuable discovery, in that, it has given a most admirable method of ridding seed grain of smut.

Bulletin No. 12, Kansas Experimental Station, 1890.

In one hundred plat experiments on stinking smut of wheat, conducted at Manhattan, Kansas, in which a great number of different treatments were tried, Prof. Kellerman† found that immersion in water, fifteen minutes, at 132 degrees Fahr. gave results preferable to any of the different methods.

It is further worthy of note that in every case in which hot water has been reported as successfully used, that there has been an apparent increase in the yield not accounted for by the increase because of a lack of smut. Indeed there can be little doubt that the treatment materially hastens germination without damaging after effects. This is wherein the hot water is much preferable to the copper sulphate. After the hot-water treatment the seed is left practically in the same shape as before being treated, save only that the smut has been killed; while in the caae of the copper sulphate a certain amoumt of the poisonous substance remains with the grain and may injure the health of the young plant.

*Arthur Bulletin No. 32, Indiana Experimental Station, p. 8, 1890.

Since Jensen‘s introduction of the hot-water treatment some valuable work has been done by way of testing the germination of wheat treated at different temperatures in hot water, by which it is indicated that wheat remains uninjured by a five-minute immersion at 135 degrees Fahr.;* but longer exposure at that temperature, or a similar exposure at a higher temperature, reduces the germination. An exposure of five minutes duration to water of 1-10 degrees Fahr. will destroy about twenty per cent. of the seeds.

The hot-water treatment is thus seen to consist in the immersion of the seed a limited time in water at a temperature high enough to destroy the smut without injuring the seed grain. Ten minutes immersion at 133 degrees Fahr. or fifteen minutes at 132 degrees Fahr. may be considered as good data by which to work. Similar exposures at temperatures greater than those given approach the danger line to germination, while ten minute exposure at a temperature less than 132 degrees Fahr. is not liable to prove wholly effective.

If the vessels are of such a nature as to allow of heating, the temperature of the water may be kept fairly constant by a slow fire. If wooden vessels, such as casks or tubs, are used, the temperature must be regulated by the addition of cold or hot water as the case may require.

The mechanical portion of the process is less difficult than the copper sulphate method. Have at hand two large tanks, boilers, kettles or such other reasonably suitable vessels as may be attainable containing sufficient water to immerse a sack holding a bushel or more of the seed. Keep the water in vessel No. 1 at about 125 to 130 degrees Fahr. and that in No. 2 at 133 degrees Fahr.†

The seed to be treated should be enclosed in porous sacks which will allow free access of the water. The ordinary gunny or coffee sack is to be preferred. In filling the sacks enough room should he left to allow free movement of the enclosed grain. In treatment, first plunge the sack into vessel No. l in order to bring the temperature of the grain more nearly to that of the water in vessel No. 2. After a few seconds remove and immerse in vessel No. 2. Knead or work the sack about so as to bring all the grain in contact with the hot water. After ten minutes immersion in No. 2 remove the sack, plunge it in cold water and spread the grain out to dry. The greatest care should be exercised not to allow the water in bath No. 2 to attain a temperature greater than that given above. It the temperature of the water stands as low as 131-132 degrees Fahr. allow the sacks to remain immersed fifteen minutes. Never under any circumstances allow the temperature of the water to reach 135 degrees Fahr. or immerse the seed a longer time than that designated for the given degrees of temperature.