72 THE POTATO. 



Phellomyces causes the formation of discoloured patches in 

 the skin of the tuber, in the midst of which are generally 

 present the minute sclerotia 0.1 mm. in diameter, just re- 

 cognisable in washed tubers with the naked eye. In mild 

 attacks, the fungus simply makes the tuber unsightly; in 

 more severe cases it strips off layer after layer of the pro- 

 tecting skin of the tuber, and may ultimately penetrate 

 through the skin into the flesh of the tuber, killing the 

 protoplasm, sending the mycelial hyphse between and 

 through the cells, and boring into the starsh grains. Phel- 

 lomyces can pass from seed tubers to the resulting crop, 

 and is communicable from infected ground to healthy 

 tubers grown in it. 



REMEDIES. Of course, but little is known at present as 

 to what steps to take to arrest the spread of this fungus. 

 Professor Johnson, however, found soaking the diseased 

 tubers in 0.8 per cent, solution of formalin for one and 

 a-half hours destroyed the fungus control, untreated tubers 

 giving a diseased crop. Three varieties imported from 

 France, planted in Connemara, gave crops showing Sclero- 

 tinia sclerotiorum, and Phellomyces sclerotiophorus, all 

 unknown in France, on the potato up to the present. 

 Frank first saw the fungus in various parts of Germany 

 in 1894. 



Potato Scab. This is said by one authority to be a 

 disease of bacterial origin, the germ being Micrococcus 

 pellucidus. It causes scab-like eruptions to form on the 

 surface of the tubers which render them unsightly. It has 

 been found by experiment that tubers grown in sour soils, 

 or where lime, cinder ashes, or farmyard manure has been 

 lavishly used, are most susceptible to infection. Another 

 authority describes the disease as being caused by a fungus, 

 Sorosporium scabies. He says it forms large olive scabs 

 or patches on the skin of fully-grow T n tubers. According 

 to him, it is not very injurious, although depreciating the 

 market value of the tubers. 



REMEDIES Seed which is not known to be all right 



