INFLUENCE OP GERMICIDES ON GERMINATION. 199 



In 1891, Kellerman ST., recommended hot water over all other fungicides for great 

 efficiency without injury to seeds. His experiments were with wheat kernels for the pre- 

 vention of stinking smut. As a result of many experiments (about 70) he recommends 

 exposure for 15 minutes to a temperature of 131 F. (55 C.). Hot water for 5 minutes at 

 137 F. and at 138 F. (seeds previously soaked 10 hours) destroyed all the grains. The 

 following treatments greatly injured or nearly or quite destroyed the grains : Bordeaux, 24 

 hours; same, half strength ; i per cent copper sulphate, 24 hours; i per cent copper acetate, 

 24 hours; i per cent copper chloride, 24 hours; i per cent potassium bichromate, 24 hours. 

 The following treatments gave reasonably good yields, i.e., better than the checks, but not 

 as good as the hot water: Copper sulphate 0.5 per cent, 24 hours, limed; copper sulphate 

 0.5 per cent, 12 hours, limed; copper acetate 0.5 per cent, 24 hours; copper nitrate i.o 

 per cent, 24 hours; copper nitrate 0.5 per cent, 24 hours; mercuric chloride 0.05 per cent, 

 24 hours. The following gave a yield nearly equal to the checks: Eau celeste, 24 hours; 

 mercuric chloride, o.i per cent, 24 hours. Ratio of grain to volume of fluid not given. Hot 

 water at 136 F. (57.7 C.) for 5 minutes, then quickly cooled, appears to be the severest 

 exposure compatible with a good crop. 



In 1893, Hitchcock and Carleton published the results of their experiments with maize. 

 They tested the effect on germination of 82 chemicals in various strengths, making a total 

 of 400 experiments. 



They obtained in moist sand a germination of 80 to 100 per cent (retarded) after 

 exposure to the following strengths of mercuric chloride water: o.i per cent for i, 3, 5, 8, 

 hours; i.o per cent for i hour. One per cent mercuric chloride for 24 hours or 3 per cent 

 for i hour killed all. Chromic acid i per cent for 48 hours gave 75 per cent retarded germi- 

 nations. Copper chloride 10 per cent for 24 hours gave 100 per cent retarded germinations. 

 Copper nitrate 10 per cent for 24 hours gave about 80 per cent retarded germinations. 

 Potassium permanganate 2.5 per cent for 24 hours gave 100 per cent germinations. Hy- 

 posulphite of soda 10 per cent for 24 hours gave full germinations. From 80 to 100 per cent 

 of retarded germinations were obtained after exposure to potassium cyanide as follows: 

 i per cent, i hour; 5 per cent, i and 3 hours; 10 per cent, i hour. The same, 0.5 per cent 

 for i hour scarcely affected germination. 



In 1897, Bolley published studies on the fungicidal treatment of wheat, oats and 

 barley which he had carried on for a period of 5 years. The following are some of his con- 

 clusions respecting resistance of the dry grain. He states that if the wheat grain is dried 

 at once germination is not retarded by applying corrosive sublimate solutions in strengths 

 up to 4 parts in 1,000 parts of water: Of selected seed of Scotch Fife wheat exposed 2 

 minutes, 95 per cent germinated; exposed 3 minutes, 82 per cent germinated; 4 minutes, 

 72 per cent; 5 minutes, 78 per cent; 6 minutes, 67 per cent; 7 minutes, 45 per cent; 20 

 minutes, 17 per cent; 25 minutes, o. As little as o.i per cent corrosive sublimate weakened 

 the first growth in a rapidly increasing degree in exposures longer than 3 minutes, but even 

 from too strong treatments the final after-growth is stronger than from untreated grain. 

 Mixed samples of oats treated with 0.3 per cent corrosive sublimate water for 30 minutes 

 gave good first growth (94 to 100 per cent germinations) and a good yield per acre. Barley 

 after 15 minutes exposure to 0.3 per cent mercuric chloride gave 94 per cent germinations. 



Seed wheat treated 10 minutes or less with i to 2 per cent solution of formalin gave a 

 normal number of germinations or better, but soaking over 10 minutes decreased slightly 

 the per cent of germinating seeds. Exposure for 10 minutes to 10 per cent killed all, and 

 merely dipping into 5 per cent reduced the germinations to 34 per cent. Subsequent experi- 

 ments showed that wheat or oats would germinate perfectly after soaking in 0.4 per cent 

 formalin i to 3 hours. 



Seed wheat will stand an exposure of i minute at 150 F. (65.5 C.) and give 80 to 90 

 per cent of germinations. Oats exposed to hot water at 140 to 143 F. for 5 minutes gave 



