34 INSECTICIDES, FUNGICIDES, AND WEED KILLERS. 



examine the action of Jensen's treatment on each of its parasites, 

 Ustilago Hordei, Bref., on barley (Hordeum vulgare) and Ustilago 

 Jensenii, Eost., on barley (Hordeum distichum). The steeping of 

 grains of barley exhibits certain difliculties when these are still sur- 

 rounded with glumes. By ordinary steeping, the spores between the 

 grains and the glumes are not killed even if the water is raised to 60° 

 C. (140' F.), whilst in an atmosphere containing the vapour of water, 

 Jensen has observed destruction to be complete at 524^° C. (1264° F.). 

 Eriksson got excellent results by softening them for four hours in cold 

 water before steeping, and allowing them to swell for four hours in an 

 aerated place, afterwards bagging them up. It suffices, therefore, to 

 immerse the grain for live minutes at 52-5° C. (1264° F., Jensen), at 

 w^hich heat all the spores perish. The water can, without fear of 

 diminishing the germinative capacity of the seed, be heated up to 60° 

 C. (140° F.), barley standing that heat without injury. According to 

 Kuhn, it is injurious to leave the grain for twelve hours in cold water 

 before proceeding to the (hot) steep, but by not exceeding four hours. 

 Sorauer found that such was in no way injurious to the development 

 of the seeds. Kellermann, Swingle, and Kirchner dispense entirely 

 with the first immersion in cold water, and claim to have obtained satis- 

 factory results by one dip in hot water at 52-5° C. (126^° F.), even if 

 the grains be glumed. Kirchner found that after a dip of five minutes 

 in water of 56° C. (132 -8° F.) grains of seed-barley germinated thus : — 



TABLE V. — Showing Effect of^Steepmg Seed-Barleij in Hot Water on Germin- 

 ative Capacitij. 



Germinated Germinated 



after tivo days. after fen days. 



Per cent. Per cent. 



Treated .... 74-5 98-0 



Untreated .... 69-75 97-0 



Besides the disinfectant action there is thus an evident increase 

 in the germinative capacity of the seeds. Whilst the researches of 

 Kellermann, Swingle, Jensen, Linhart and Mezej^ Prillieux and 

 Schribaux confirm this observation, Hollrung is of a conti-ary opinion. 



Ustilago Tritici, Jensen (smut of wheat, Triticum Sativum) ; Til- 

 letia caries, Tul., " stinking smut " or " bunt " of wheat ; Tilletia levis, 

 Kuhn (loose or flying smut of wheat). — According to Herzberg, the 

 spores of Ustilago Tritici are destroyed at a temperature of 48° C. 

 (118-4° F.), and those of Tilletia do not germinate after immersion in 

 water of 55°-56" C. (131"-132-8° F.). By treating wheat grain by one 

 immex'sion of five to fifteen minutes in water of 56° C. (132*8° F.), 

 Sorauer obtained the following results : — 



TABLE Yl.— Result of Steeping Seed-Wheat in Hot Water dxiring different 

 Periods of Time. 



Untreated grain 87 per cent of plants which gave 



5-17 per cent of " bunted " ears. 

 Grain treated five minutes . . .91 per cent of plants which gave 



0-225 per cent of " bunted " ears. 



„ ten minutes . . . S7| per cent of plants which gave 



6-157 per cent of " bunted " ears. 



„ fifteen minutes . . 87S per cent of plants which gave 



0-071 per cent of " bunted " ears. 



