798 EXPERIMENT STATION RECORD. 



"(7) As soon as the fuugiis ruptures the tissues evaporation is increased about 

 one-fifth above the normal. In consequence of this the reserve water in the cells is 

 gradually used up. This is followed by loss of turgidity and other physiological 

 changes which lead to the gradual death and casting of the leaves." 



The effectiveness of corrosive sublimate as a preventive of 

 potato scab, H. L. Bollby {Proc. Soc. Promotion Agl. Sci. 1896, pp. 

 75-81, fig. 1). — The author reports a series of investigations uudertaken 

 on account of the criticism ' "that the corrosive sublimate treatment 

 is ineffectual against scab when tested in connection with soil fertilized 

 with lime and other alkaline eu gendering agents." 



The first experiment was made in a greenhouse, the jjotatoes being 

 grown in boxes containing virgin prairie subsoil. The seed tubers were 

 scabby and had been treated by soaking in varying strengths of corro- 

 sive sublimate solutions. Xo contamination could have taken place 

 except through the use of tap water. The soil received various quanti 

 ties of lime, and when the crop was dug all tlie tubers were washed and 

 thoroughly inspected. All were practically free from scab, the lime 

 having had no effect in increasing the disease. 



In the field trial the soil had not recently grown potatoes, although 

 fields adjoining on 2 sides had been planted to j)otatoes 2 seasons pre- 

 vious and high winds had drifted considerable dust over the trial plat 

 resulting, as it proved, in a very thorough contamination. The seed 

 tubers were treated and the soil received lime in varying amounts. 

 The tubers dug from all the rows were more or less scabbed, from 10 to 

 20 per cent being the lowest per cent affected. In the check rows 

 where the tubers had received no i^reliminary treatment about 98 per 

 cent were diseased. It is said that the addition of lime gave no increase 

 in scabbiuess. The soil at the station is considered sufficiently alka- 

 line for the growth of the fungus. The author thinks it probable that 

 in acid soils where there is chance for infection the addition of lime 

 would be undesirable. 



A limited test made with flowers of sulphur for the prevention of 

 scab indicated that the substance was without effect in preventing the 

 development of the fungus. 



Potato scab, H. J. Wheeler and G. M. Tucker (Rhode Island Sta. 

 Bui. 40, pp. 80-96, figs. 4). — The authors, in continuation of their pre- 

 vious work', have again investigated the effect of various substances 

 in increasing or decreasing the amount of scab on potatoes when grown 

 under different conditions of treatment. 



The effect of sodium chlorid, sodium carbonate, and oxalic acid upon 

 the development of scab on tubers when grown with the aid of barn- 

 yard manure was investigated by means of pot exi)eriments. The 

 results confirmed those of the previous year and indicate that under 

 the conditions of the experiment common salt tends to decrease the 

 amount of scab and sodium carbonate to increase it. Oxalic acid 



' Rhode Island Sta. Bui 33 (E. S. R., 7, p. 782). 



-Rhode Island Sta. Bui. 30 (E. S. R., 6, p. 906) and Bui. 33 (E. S. R., 7, p. 782). 



