DISEASE OF TURNIPS. Ill 



The first important notice of this fungus is from the pen of the 

 Kev- M. J. Berkeley, and is to be found in the Gardeners 1 

 Chronicle for 1854, p. 236. Here we find ihat the pest has 

 appeared, not on the Scrophulariacese as before, but upon one of 

 the Rosaceee in the cultivated strawberry. Mr. Berkeley describes 

 the entire destruction of a crop of Cuthill's Black Prince straw- 

 berry, the little white mildew attacking first the leaves, and then 

 infesting with increased vigour the flowers and footstalks, and 

 ultimately inducing the wretched appearance so common with 

 the mildew of the vine. It is strange in the above instance that 

 the oidium confined itself to the Black Prince, as plants of 

 Keens' Seedling on the same shelf were perfectly free from the 

 taint. Mr. Berkeley then describes the form and size of the 

 spores, identifying the plant with the Oidium of the Mullein. 

 He mentions how it may be destroyed with lime and sulphur, 

 but a remedy of this nature cannot be applied over vast areas, as 

 in the case of the turnip fields now under consideration. 



About a fortnight ago Professor James Buckmau, of Bradford 

 Abbas, Sherborne, Dorsetshire, sent me some mildewed turnip 

 leaves, with a request that I should examine them. I paid little 

 attention to them at first, thinking they were probably afflicted 

 with the old turnip mildew (Peronospora parasitica), so common 

 just now. But it soon struck me that I had never seen or heard 

 of such a profuse and overwhelming growth of this parasite, 

 neither had I ever seen it densely covering both sides of the 

 leaves as in the present case, A glance through the microscope 

 soon showed the mildew to be an Oidium and not a Peronospora. 



Oidium. Balsarnii is mentioned as a name, but not described in 

 detail either in Mr. Berkeley's Outlines of Fungology or in Dr. 

 Cooke's Handbook, and it does not occur at all in the recently 

 published Mycologia Scotica, by the Rev, John Stevenson certain 

 varieties of Oidium, and this amongst them, being justly con- 

 sidered as mere states of other fungi. Several species of Oidium 

 are known to ultimately take another form, but no such condition 

 is as yet kown in what may now bo appropriately termed tho 

 "Turnip Oidium." 



