Pkthybkidge and Lafferty — Dry-Rot of the Potato Tuber. 217 



flowers of sulphur. They were then wounded, and into the wounds flowers 

 of sulphur was thoroughly rubbed. Finally, F. cmruleum was inoculated 

 into the sulphured wounds. 



Both lots of tubers were kept under the same conditions at laboratory 

 temperature, and were examined at the end of a month. It was then found 

 that the rot had become thoroughly established in all ten tubers, and that 

 the presence of the sulphur had exercised no influence either in preventing 

 infection or in retarding decay. Hence the use of sulphur for the control 

 of this rot as suggested by Massee 1 cannot be recommended. A similar 

 experiment was carried out using slaked lime in the place of sulphur, and the 

 result was identical. 



It might be expected that at low temperatures the rot would be inhibited. 

 Yet it must not be forgotten that it proceeds in potato pits and stores during 

 the winter months when the temperatures in them certainly cannot be high. 

 It was found that tubers artificially inoculated with the fungus and kept in 

 an unheated greenhouse, where the temperature varied from 0°C. to 6°C. 

 during the nights, and on some occasions rose to a maximum of 2.5°C. during a 

 portion of the day, became infected quite as easily and rotted quite as rapidly 

 as others inoculated at the same time and kept in an incubator at a constant 

 temperature of 20 C C, while a similar lot inoculated and kept at 30 c O. remained 

 quite free from infection. It is doubtful, therefore, whether keeping tubers 

 at an unusually low temperature, even if this could be managed in practice, 

 would be a successful method of control, and it is by no means certain that 

 such treatment would be good for the tubers themselves. 



Affected tubers should certainly not be used for seed, for they give either 

 no produce or only a poor " stand." Cutting sets from affected seed tubers and 

 planting them is likely to lead to disastrous results, and this should be 

 avoided. 



In the raising and subsequent handling of potatoes care should be taken 

 not to bruise or wound them, particularly if they are intended for seed 

 purposes. This applies with special force to some of the early varieties, which 

 have comparatively thin skins, and are often raised before they are thoroughly 

 ripe, when the skins are peculiarly liable to abrasion and other injury. Care 

 should also be taken when planting sprouted potatoes to avoid breaking off 

 the sprouts. The practice of deliberately breaking off the sprouts to induce 

 the growth of a further set is one which is to be condemned from all points 

 of view. 



" Prevention is better than cure," but seeing that we do not yet really 



'Diseases of Cultivated Plants and Trees, p. 183. 



SCIENT. PROC. R.D.S., VOL. XV., NO. XXI. 2 M 



