1080 EXPERIMENT STATION RECORD. 



the increased yield being attributed to the beneficial effects of the Bordeaux mixture, 

 not only in checking the development of the fungus, but in deterring insect attacks. 



In investigations on the relation of the date of digging to the development of the 

 potato rot, results quite different from those previously reported (E. S. R., 17, p. 261) 

 were obtained. In 1905 there was a greater loss from later digging than from earlier, 

 and this is at variance with the previous rule laid down that digging should be 

 deferred as long as possible where the rot is expected. In the authors' opinion this 

 rule will have to be modified by making an exception of heavy wet soils during wet 

 seasons. 



Experiments were carried on to test the effect of liming, disinfection with formalin, 

 sun-drying the tubers, and the temperature of storage on the development of rot in 

 potatoes. It was found that instead of being an advantage in the preservation of 

 tubers, the application of lime actually favored the development of rot. Disinfecting 

 with formalin was without any material effect in checking it. In testing the relation 

 of moisture to the development of rot it was found that potatoes exposed as much as 

 practicable to sun and air prior to storage are less subject to rot than those stored 

 immediately. The various temperatures of storage investigated were 40, 53, and 70°, 

 and the greatest proportion of the crop saved was at the lowest temperature. 



In studying the time and method of tuber infection different lots were subjected 

 to different treatments. One lot was exposed for 36 hours to infection from blight- 

 ing tubers immediately after digging, a second lot was not artificially infected but 

 kept moist for 36 hours, and a third lot was stored without treatment immediately 

 after digging. The relative loss was 92 per cent where the tubers were infected and 

 not washed, 100 per cent where infected and washed, 77 per cent where not infected 

 but kept moist for 36 hours, and 54 per cent where stored at once without any treat- 

 ment, Concerning the possibility of spread in the storage cellar, it was found that 

 spores may be produced in storage, and that well ripened sound tubers were readily 

 inoculated with the fungus spores. From this it appears that there is no doubt as 

 to the possibility of infection of tubers in storage. 



In continuation of trials of gaseous disinfection for potato scab (E. S. R., 17, p. 261), 

 the authors tested the relative value of gas treatment as compared with soaking seed 

 for disinfection against scab, and also the merits of different ways of generating the 

 gas. All the methods of disinfection showed marked gains in smooth tubers, but 

 none of them gave a crop wholly free from scab. The average results obtained with 

 the vapor treatments were better than those secured where the seed tubers were 

 soaked in formalin solution, and the authors are led to recommend treatment of seed 

 tubers with formalin gas by the permanganate method without the addition of steam. 

 The cost of this treatment would be approximately §1.50 per 1,000 cu. ft., and this 

 method is recommended only for those seed potato specialists who may wish to 

 disinfect large quantities of tubers. 



Concerning disease resistance of potatoes, L. R. Jones ( Vermont Sta. Rpt. 

 1905, pp. 264-267). — A brief account is given of investigations carried on by the 

 author in connection with the Bureau of Plant Industry of this Department regard- 

 ing the resistance of potatoes to various diseases, a preliminary report on. which has 

 already been issued (E. S. R., 17, p. 60). 



The potato leaf curl (Jour. Bd. Agr. [London], 12 (1905), No. 8, pp. 476-478, 

 fig. 1). — A description is given of the potato leaf curl or early blight (Macrosporium 

 solani), and its occurrence is noted on Solatium commersoni grown at Kew. 



Sal Bordeaux for potato blight, C. D. Woods and J. M. Bartlett (Maine Sta. 

 Bid. 126, pp. 34, 35).— In a previous publication of the station (E. S. R., 16, p. 1093) 

 it was shown that dry Bordeaux as a fungicide was inferior to Bordeaux mixture as 

 usually applied. 



In 1905 an experiment was carried on to test the value of a dust spray known as 

 Sal Bordeaux. This consists of equal parts of lime and exceedingly finely ground 



