8 
his results. He went still further and claimed that the smuts of oats, 
wheat, and barley gain entrance into their hosts through the first 
light- eclarcal yellowish-green sheathing leaf. 
Brefeld! asserts that after the green leaves have pushed their way 
through the primary leaf to a distance of 1 cm. or more, all danger of 
infection capable of causing smutted heads of grain is passed. More 
recent observations show that corn is an exception to this rule. 
H. Marshall Ward? thinks it probable that the sporidia can gain 
entrance through any of the embryonic tissues and infect the host 
plant, developing with its fruiting organs. If, then, the fungus can 
enter only at the collar of the plant, a few hours in germination may 
make quite a difference in the future seedling. 
SUMMARY OF EXPERIMENTS WITH COPPER SULPHATE TO PREVENT 
SMUT OF OATS, WHEAT, BARLEY, ETC. 
As has been mentioned, several methods of treatment have been dis- 
covered that are more or less effective in preventing the smut of oats, 
wheat, barley, etc. In the case of oat smut (Ustilago avene (Pers.) 
Jensen), aS well as allied species on other hosts, the most successful 
means of prevention is that known as the hot-water treatment, discov- 
ered by J. L. Jensen,? of Denmark. It consists in treating the seed 
oats for fifteen minutes with water heated to a temperature of 132° to 
135° F. This treatment kills all the smut spores without in any way 
injuring the vitality of the seed. 
As has long been known, the presence of some of the salts of copper, 
even in dilute solutions, will prevent the germination of the spores of 
fungi, a fact to which the efficiency of some of our most important fun- 
gicides is due. Of the salts of copper, perhaps the most effective is the 
sulphate, and so extensively is this employed that its use is now almost 
universal. Although some writers claim that it is more injurious than 
beneficial, yet, when considered from an economic standpoint, the ease 
with which it can be applied is no doubt greatly in its favor. 
Tessier* seems to have been the first to use copper compounds for 
the prevention of smut, his experiments having been carried on in 
1789. It would appear, home ven that no immediate advantage resulted 
from his work. 
Prevost,’ in 1807, discovered that smut spores would not germinate 
in the presence of soluble copper compounds. 
Sinclair® claims that the use of copper for the prevention of grain 
smuts had long been practiced throughout Flanders. 
1Nachr. aus dem Kl. Landw., Berlin, No. 221, p. 1591. 
2Gard. Chron., 5, ser. 3, 1889, p. 234. 
3Gard. Chron., 3, ser. 3, 1888, p. 555. 
4Art. Carie, p. 721. 
5Mem. Carie Charbon des blés, Paris, 1807, p. 65. 
5 Code of Agriculture, Appendix, p. 62. 
