DISEASES OF PLANTS. 659 



of barley, winter wheat, oats, and maize were sprayed with these herbicides, and 

 where properly ai)plied resulted in the destruction of the wild mustard, the wild 

 radish, and in a number of instances of the field poppy, crowfoot, cardoons, etc. In 

 general, all the treatments were successful, but on account of cheapness the iron sul- 

 phate is given the preference. It is believed that by the use of this herbicide it will 

 be possible to destroy these weeds growing in fields of cereals. 



DISEASES OF PLANTS. 



Notes on fungus diseases of plants, J. Ray {Rev. Gen. Bot., 13 {1901), No. 148, 

 ■pp. 145-151). — The author believes that it is possible, within certain limits, to pre- 

 vent attacks of fungus parasites through the presence of inimical substances in the 

 tissues of the host plant. Among the external parasites the effect of the host is inap- 

 jjreciable and fungicides must be emjiloyed in combating them. For internal parasites 

 a number of alternates are presented. A brief report is given of experiments in which 

 various chemicals were injected into the plants, indicating, the author believes, that 

 the injection of the juices of plants not subject to attacks of a specific organism will 

 secure immunity for the treated plant from attacks of that fungus. The principal part 

 of the paper is taken up with an account of experiments in which immunity to disease 

 was secured by producing a mild form of disease through inoculation with attenuated 

 cultures of the fungi, or by the use of toxins derived from pure cultures of the organ- 

 isms. The methods of attenuation were those usually employed in such investiga- 

 tions and consisted of heat, light, and cold. Experiments were conducted with 

 wheat, oats, luj^ines, beans, sunflowers, radishes, and mustard, all of which — with the 

 exception of the mustard — are subject to a Ijacterial rot caused by Bacillus putrefndens. 

 The experiments with the lupines and beans are reported at considerable length. 

 The bacteria cause a peculiar rotting of the tissues, accompanied by an exudation of 

 viscous gum which has a very characteristic odor. Inoculations with attenuated 

 cultures, or with a' solution obtained by dissolving the alcoholic precipitate secured 

 from the cultures, produced a mild form of disease which apparently rendered plants 

 immune to subsequent attack. The author believes that the occasional immunity 

 and resistance of some individuals fo disease is largely brought about in this manner. 



Result of experiments for the prevention of bunt in wheat, W. Farrer 

 {Agr. Gaz. New South ]V<iles, 12 {1901), No. 4, pp. 419-430) .—In 1899 and 1900 the 

 author conducted a number of experiments for the prevention of bunt in wheat at 

 Lambrigg, Australia. The results of his experiments in 1899 showed that copper 

 sulphate was not to be depended upon as a fungicide for the prevention of bunt. 

 Repeating his experiments in 1900 the results obtained were much more favorable 

 for the use of fungicides than the previous season. The experiments were con- 

 ducted by drilling different varieties of wheat in 20-yard rows in which badly 

 infested seed was used or snuit balls were broken and mixed with the seed before treat- 

 ment. The experiments show that formalin was efficient in destroying a consider- 

 able portion of the fungus spores, and from the tabular statement but few plants 

 produced any snuitty heads whicli had been treated either with formalin or copper 

 sulphate. The fungicides, however, were in some instances decidedly injurious to the 

 seed. Considerable difference in the susceptibility of varieties to smut is reported. 

 A series of experiments was conducted in which the seed was soaked in hot water and 

 other lots subjected to dry heat, the temperatures ranging from 180 to 180° F., but 

 negative results were obtained. An experiment was attempted in which it was 

 sought to infest wheat through the soil l)y stirring smut balls in the soil. The seed 

 wheat sown was from plants which showed no indication of disease, and of the plants 

 which grew and came to maturity .every one was found to be free of bunt. In a 

 somewhat similar experiment it was shown that plants grown from seed which had 

 been produced on noninfested plants did not show any disease. 



18265— No. 7 5 



