846 Report on Destructive Insects and Pests. [Jan., 



have been made, and these afford a base for subsequent ex- 

 periment. The observations resolve themselves into two 

 classes: (1) on the fungicides used as remedies for disease 

 either as curatives or preventives, and (2) on the varieties 

 of potatoes most liable and least liable to attack. 



The remedies tried were (1) flowers of sulphur, (2) soot, 

 and (3) lime, all of which were reported to have met with 

 some success in 1908.* Both in pot and garden experi- 

 ments sulphur has been found to keep the disease in 

 check, even if it has not prevented it. The best and 

 most economical way to use sulphur is first to dust the 

 sets, preferably when stored in the autumn, and then to 

 sprinkle them freely with flowers of sulphur as they lie 

 in the drills before covering up. Before the plants are 

 earthed up the soil should be dusted with sulphur, to prevent 

 the disease from attacking the haulms, at the ground surface. 

 Soot has been sprinkled on the sets as they lay in the drills 

 with some success, and two cases are known where freshly 

 slaked lime sprinkled as described above has checked the 

 disease. Gas lime, on the other hand, laid on in the winter 

 is said to have been ineffectual. Kainit, quicklime, and salt, 

 applied to the ground in the winter, have not proved of any 

 value, and trenching the ground to the depth of 2J to 3 ft, 

 has also proved of no avail. Evidence as to the susceptibility 

 of the different varieties of potatoes is more definite. The 

 variety named Snowdrop is usually, possibly always, im- 

 mune. Maincrop, Langworthy, Conquest, and Golden 

 Wonder are not attacked. All varieties belonging to the 

 Up-to-date class take the disease very readily and very badly. 

 With the object of arriving at some trustworthy informa- 

 tion the Board arranged for two classes of experiments to 

 be carried out during 1909. Experimental plots were 

 secured in Lancashire, Cheshire, Shropshire, and Brecon- 

 shire, and planted with seventeen selected varieties of 

 potatoes; while another class of experiment has been ar- 

 ranged to test the effects of possible remedies. Further, in 

 order to test the use of sulphur, a number of cottagers and 

 allotment holders have been supplied with a few pounds of 

 sulphur for the treatment of their gardens. 



* In the field experiments of 1909 none of these remedies were effective. For a 

 summary of the results of the experiments, see Journal December, 1909, p. 762. 



