PESTS OF GARDEN VEGETABLES. 



815 



Potato Tumouk. 

 CEdomyces leproides (Trabut.). 



Tbis disease made its appearance in this country in 1901, when a 

 wbole crop of Potatos was destroyed by its ravages, and it has since 

 appeared in other districts. At first it was called on the Continent by 

 the name of Gkrysophlyctis endobiotica (Schilbersky), and was supposed 

 to be an entirely new type of disease, but afterwards when specimens were 

 brought to the notice of Dr. Magnus, he determined that it was the same 

 fungus as that which caused tumour on Beetroot, and hence should retain 

 the name of CEdomyces leproides. The Potatos when attacked are soon 

 either wholly or partially swollen on the surface in a tuberculose manner, 

 turning blackish, and presenting in cells beneath the cuticle a mass of 

 large oval conidia, of a brown colour, with a short hyaline pedicel, which 

 is swollen about the centre. Altogether the disease presents the same 

 features as when it occurs on Beetroot, and is, of course, liable to be 

 transferred from one to the other. 



Hitherto no remedy has been discovered, and wherever it appears it 

 would be advisable not to plant another crop of Potatos on the same soil 

 until after the cultivation of some intermediate crop of a different 

 character, and the soil has been disinfected from any trace of the fungus. 



For further notes see " Beetroot Tumour." 



Potato Disease. 

 Phytophthora infestans (De Bary), PI. IX. fig. 118. 



So many volumes have been written in connection with the Potato 

 disease that little remains for us to say. Unfortunately, its ravages are 

 too well known to need description, and a patent universal remedy we 

 have not yet found. 



The mycelium of this rot mould is more slender than usual, and the 

 fertile threads are also comparatively slender, being attenuated upwards. 

 These threads are also sparingly branched in the upper portion, with a 

 few slender tapering branches, which are either simple or sometimes 

 divided. On the branches are scattered swollen processes, which corre- 

 spond to the points of origin of the conidia. The latter are elliptical and 

 colourless, with a prominent papilla or teat-like projection at the apex 

 (25-30 + 15-20 fx). 



The life-history of the rot moulds is given in the Introduction. 

 The question of resting spores in this species must still be open to 

 individual opinion upon the strength of the evidence afforded, to which 

 we give references. 



To a certain extent spraying with Bordeaux Mixture has been of 

 service. A damp situation is favourable to the disease, and so is a wet 

 season. 



Sacc. Syll. vii. 802 ; Cooke, M. F. f. 264 ; Cooke, Hdbk. No. 1774 ; 

 Mass. PI. Dis. 62, fig. 7 ; Mass. B. F. p. Ill, figs. 121-126 ; Grevillea, 

 v. p. 18, pi. 70-73 ; Ward, Dis. p. 59 ; Gard. Chron. July 1875 ; Smith, 

 Field Crops, 275 ; Tubeuf,Dis. p. 119. 



