242 EXPERIMENT STATION EECORD. 



ciple which has been pronounced equal to lactucarium of German origin. As 

 lactucarium is a recognized drug of the Pharmacopoeia, the author suggests the 

 possibility of combining the production of lactucarium and rubber in the North 

 Temperate Zone. 



DISEASES OF PLANTS. 



Report of the Dominion botanist, H. T. GtJssow (Canada Expt. Farms Rpts. 

 1912, pp. 103-201, 212-215, pis. 2, figs. ^). — Miscellaneous investigations are 

 reported upon, among them studies on the effect upon vegetation of water 

 treated with hypochlorite of lime used against typhoid fever, some diseases 

 of cereals, further observations on frosted wheat, and diseases of potatoes and 

 other root crops, and of apples, small fruits, and ornamentals. 



The results of the experiment on the effect of water containing hypochlorite 

 of lime showed that it was without injurious effect when applied directly or 

 indirectly to cultivated plants. 



In connection with some of the potato diseases, particularly the Rhizoctonia 

 disease, due to Corticium vagum solani, experiments in treating the tubers with 

 formaldehyde and corrosive sublimate solutions showed that formaUn was 

 almost without effect, while the potatoes grown from tubers treated with cor- 

 losive sublimate were practically clean. In connection with the treatment of 

 potatoes with corrosive sublimate, cooperative investigations were carried on 

 with the chemist of the station to determine the amount of mercuric bichlorid 

 absorbed, and it was found that in 3 lbs. of treated potatoes 0.05 gm. of 

 mercuric bichlorid was present. In the author's opinion it is thought that this 

 amount might prove injurious and, as a consequence, that potatoes intended 

 for consumption should not be treated with corrosive sublimate. 



Notes are given on experiments on the vegetation of Sable Island, and on the 

 botanic gardens and the herbarium for seed collection. 



Report of plant patholog'ist, H. E. Stevens (Florida Sta. Rpt. 1912, pp. 

 XCIII-XGYIII). — The author describes experiments on melanose of orange, 

 citrus scab, and late blight of the Irish potato. 



The investigations have shown that melanose is due to the same fungus as 

 that causing stem-end rot (E. S. R., 28, p. G51). Infection experiments have 

 produced the disease, which is found to be influenced by moisture and succu- 

 lence of tissues. 



The investigation of citrus scab has been more fully described elsewhere 

 (E. S. R., 27, p. 653). • 



A serious outbreak of late blight of potatoes was called to the author's atten- 

 tion. Spraying with Bordeaux mixture was recommended, and where the spray- 

 ing was well done favorable results w6re obtained. 



Report of assistant plant pathologist, O. F. Burger (Florida Sta. Rpt. 1912, 

 pp. XCVIII-CI). — Descriptions are given of a bacterial disease of lettuce and 

 a new cucumber disease that is apparently of bacterial origin. 



The lettuce disease was originally described by the former pathologist (B. S. 

 R., 21, p. 342). The behavior of the organism in various media is given and 

 suggestions are offered for treatment, which consists of the removal from the 

 field of all diseased plants and their destruction by burning, together with 

 directions for the care of the plants in the seed bed. 



The cucumber disease is said to have been troublesome for the past 2 years, 

 attacking leaves and fruit. An organism was isolated from the fruit and 

 inoculation experiments demonstrated its pathogenic properties. The disease 

 is said to be spreading over the entire cucumber-growing district of Florida, 

 and in some places 50 per cent of the crop was destroyed during the year 



