14 



[Vol. 10 



GARDEN 



Hegyi ('10) studied the disease on the continent of Europe, and 

 since he found that every case of "blacklegged" stalks examined 

 bore evidence of the attack of wireworms, he thinks insects are 

 a positive factor in the invasion of the host. Paine ('17) be- 

 lieves that wireworms and biting insects are undoubtedly in- 

 strumental, under certain conditions, in introducing the parasite 

 from the soil. 



Geographical distribution.— The potato blackleg disease is 

 now known to be widely distributed in the United States, Can- 

 ada, and Europe. It was reported first in the northeastern 

 United States and eastern Canada. Its spread, however, has 

 been rapid, especially throughout the northern states. The dis- 

 ease has been reported from nearly every state in the Union. 

 The records show, however, that it is essentially a cool-climate 

 disease, therefore prevailing in more southerly districts only 

 where potatoes are grown at high altitudes. 



The writer finds that this disease in Montana and other sec- 

 tions of the Northwest is caused by the same organism known to 

 prevail in the northeastern and North Central States. The re- 

 cent work by Shapovalov and Edson ('21) proves that the same 

 organism is widely distributed in the West. 



Control — Control measures should be inaugurated during the 

 growing season. The writer strongly advocates the planting of 

 a portion of the crop in a separate, if possible isolated, plot. 

 This practice enables the grower to detect, remove, and destroy 

 diseased hills at an early date. 



Inspection and roguing of the plot (or field) should be begun 

 soon after the plants are up and repeated at more or less fre- 

 quent intervals throughout the growing season, especially during 

 cool, rainy weather. Intelligent roguing will eliminate all hills 

 where vines show any symptoms of the disease. Final inspec- 

 tions should be made just before and after digging. No tubers 

 showing signs of rot or mechanical injury should be placed in 

 storage. It is highly important that all seed stock be stored 

 under favorable conditions. Slatted storage bins 8 or 9 feet 

 high, 5 or 6 feet wide, and of any convenient length are ideal. 

 In order to permit proper aeration of the potatoes, such bins 

 should have false floors and must be separated from each other 

 as well as from the walls of the cellar. The cellar should be fairly 

 moist but provision should be made by proper regulation of ven- 



