639 



The smut could be positively detected only by ciiUing open llie husks. In this 

 hidden smut, as it may be called, the outer glumes are of tlie usual si/o and shape 

 and quite sound. Usually but one grain is developed ; its hulls are sound and tightly 

 closed; the grain is smaller than usual. A rudimentary grain is usually produced 

 on its furrowed (inner) side, and this from the exterior usually shows the smut. 

 Upon forcing open the husks the larger grain is found to be more or less completely 

 destroyed by smut. • » * By careful inspection marks or characters, though 

 rather obscure, may yet be detected by which heads attacked with the hidden smut 

 may be recognized even without dissection : (1) They are usually greener in color 

 and lack the yellowish tinge of ripening heads that are sound. (2) The tips of the 

 outer glumes are usually bleached, while the bases are a deep green. (3) Ordinarily 

 some of the grains, especially the lower ones, are stunted and very evidently smaller, 

 and especially narrower than healthy ones. 



Microscopic examination showed that the spores in the hidden smut from Canadian 

 Triumph, Welcome, and White Swede are all smooth, and apparently belong to the 

 form named by us var. Icevia. The spores were sometimes found to be partially 

 immature or poorly developed, often also monstrous in form and size. But it should 

 be remarked that the var. Icsvis is not always hidden smut ; yet it never seemed to 

 occur in the loosest form of smut. 



Experiments in preventing smut in oats (pp. 102-120). — Brief accounts 

 are given of successful experiments on three farms in the use of the Jensen 

 hot-water treatment of the seed of oats to prevent smut. Descriptive 

 notes and tabulated data are also given for experiments by the station 

 in 1890 in treating the seed of oats with various fungicides before plant- 

 ing on 156 plats, 155 alternate plats being planted with untreated seed. 

 The fungicides included hot water at different temperatures (120.2° to 

 143.6° Fah.) and for different periods (3 to 20 minutes), the seed having 

 in some cases been previously soaked in water for from 1 to 8 hours ; 

 potassium sulphide, sodium hyposulphite, copper sulphate, copper 

 nitrate, sodium bicarbonate, verdigris, mercuric chloride, salicylic acid, 

 jiotassium bichromate, carbon bisulphide vapor, ammonium hydrate 

 vapor, chloroform vapor, ether vapor, castile soap solution, and cistern 

 water (24 hours). The treatments with hot water gave the best results. 



The only other treatment which gave results at all comparable with those obtained 

 by using hot water was that with one half to three fourths per cent solutions of potas- 

 sium sulphide in which the seed was allowed to stand 24 hours. When fresh solu- 

 tions were used a one fourth per cent solution did not prevent all the smut, a three 

 fourths per cent solution destroyed all the smut but injured the stand, while a one 

 half i->er cent solution destroyed all the smut without injuring the stand. » » » 



Of the hot-water treatments seven plats were planted with seed that was allowed 

 to cool gradually after immersion in hot water. In every instance corresponding 

 plats were planted with grain treated in exactly the same manner, but cooled after 

 immersion by being plunged into cold water. The cooled and uncooled seed was 

 planted in adjacent plats separated by a single untreated plat. 



lu every case the plats treated with gradually cooled seed gave a less per cent of 

 smut than those planted with seed cooled as usual. » » » 



Such a result might very naturally be expected, since the real effect of not quickly 

 cooling the seed is simply to i>rolong the action of the hot water. It is very evident 

 that such action would jiersist longest in the interior of a mass of grain, and thus 

 might overtreat (and injure) some of the graiu while other parts were not yet sufifi- 

 cientiy treated. The use of cold water insures the treatment of each grain in nearly 

 the same degree. It may yet be found possible and desirable to omit cooling the seed, 



