10 FUNGOID PESTS OF CULTIVATED PLANTS. 



In the form which is found in Britain the foliage is disfigured by 

 large blotches, or spots, on the upper surface, which are sometimes very 

 irregular and angular in shape, without any distinct border or marginal 

 line. At first they are blackish, but soon become paler and bleached in 

 the centre, leaving the blackness around the edge. The spots are sprinkled 

 with little black dots, like pin-points, which are the conceptacles, or 

 perithecia, of the fungus, and contain the spores. 



Under the microscope these perithecia are blackish, minute, rounded, 

 flattened bodies, with a pore or orifice at the apex, through which the 

 spores escape, and are more or less immersed in the substance of the leaf. 

 The sporules are oblong and colourless, minute (7 x 3 yu), with two nuclei, 

 and are produced on short stalks within the receptacles. 



In Italy this species is found growing in company with another fungus 

 of a higher development, but resembling it in external appearance. In 

 that case the spores are produced within delicate cylindrical cells, or 

 asci, to the number of eight in each ascus, and the species is called 

 Spharella Hermione, of which the above-named Phyllosticta is an 

 imperfect condition. Hitherto there is no record of the perfect con- 

 dition, or Sph&rella, having been found in this country. 



At present, so far as we are aware, this parasite is confined to Italy 

 and to isolated spots in Great Britain. 



If taken in the early stage of its appearance, and all the diseased 

 leaves are removed, so long as the plants are otherwise in a healthy con- 

 dition, they may recover. Failing this, the application of one of the 

 copper solutions should be made. 



It may occur either on the leaves of Helleborus niger, viridis, or 

 f cetidus. 



Sacc. Syll iii. 201 ; Grevillea, xiv. p. 73, No. 403. 



Another and allied species, Phyllosticta atrozonata (Voss., f.), occurs 

 on the leaves of H. viridis in Carniola. The leaf-spots are characterised 

 by concentric zones, and the sporules are smaller. 



In France another species, Phyllosticta Helteboriana (Brun.), occurs 

 on the leaves of H. fcetidus, in which the spots are smaller, rounded, and 

 margined by a brown line, whilst the sporules are smaller still. 



In Italy the leaves of H. viridis are attacked by the angular, dry, 

 pallid spots of Phyllosticta Helleboricola (Mass.), with very minute 

 sporules. So that altogether four species of the same genus of parasite 

 have occurred on the leaves of Hellebore in Europe. 



HELLEBORE LEAF-SPOT. 

 . Septoria Hellebori (Thiim.), PI. I. fig. 2. 



This little-known parasite has on one or two occasions been found on 

 the foliage of Helleborus niger in Britain, although first discovered in 

 Austria. 



The spots on the leaves are rather large and irregular, without any 

 determinate margin, and of a brown colour. The spots are sprinkled 

 with the minute black dots, as in Phyllosticta. 



