FUNGOID DISEASES OF POTATOKS 9! 



appears to be worst on land that has been recently 

 limed. 



Syniplo?ns, — The spots may be seen at liftincr 

 time, but are particularly noticeable after storing. 

 They occur particularly at the ''rose" end of the 

 potato and are black or brownish -black in colour, 

 |- to :f inch diameter, with the circumference sunken 

 and the centre raised. They penetrate the potato 

 ^ inch only (i.e. skin deep), the inner contents of 

 the tuber remaining apparently healthy. Not only 

 are the spots unsightly and reduce the market value ; 

 but if there are many of them near the " eyes," the 

 tubers are quite useless as sets.^ 



Cause. — Microscopic examination of sections 

 through the spots readily reveals the presence of 

 fungal threads (Fig. 25, A), and the culture media 

 inoculated from the inside of the pimples develop, 

 without exception, a growth of Spicaria iiivca (Fig. 

 25, B)and sometimes other fungi are present. All 

 attempts to produce the spots, however, by inocula- 

 tion of healthy tubers with .V. nivea, or the other fungi, 

 have failed. Carruthers comes to the conclusion 

 that the fungi present merely enter the lenticels as 

 saprophytes, and cause the blackening of the tissue. 

 The matter is worthy of further investigation. 



^The author considers this disease the cause of the great irregu- 

 larity in many crops of " Evergood," the fungus destroying the eyes. 

 He saw at one farm in Lincohishire in the spring of 1904 two to four 

 tons of " deaf sets " which had, fortunately, been noticed and 

 picked out before planting. 



