FUNGUS PESTS OF THE CARNATION FAMILY. 



649 



FUNGUS PESTS OF THE CARNATION FAMILY. 



By D. M. C. Cooke, M.A., LL.D., F.R.H.S., &c. 



The Carnation family may not be of overwhelming importance to 

 horticulturists, but they seem to be of sufficient value to justify an 

 attempt to bring together such information as may be available con- 

 cerning the fungoid pests to which they are liable. With this view, and 

 for this purpose, these parasites may be grouped superficially under four 

 sections. Firstly, the leaf-spotting caused by such incomplete fungi as 

 the Sphaeropsideae, and which seldom inflict greater injury than the 

 destruction of the foliage, except perhaps in the allied forms of " anthrac- 

 nose." Secondly, the less common but more destructive moulds — 

 including in that term the "rot moulds," of the same kindred as the well- 

 known Potato-disease. These consist of small white moulds, which cause 

 little serious injury, and the black moulds, which, like the Tomato-leaf 

 disease, are capable of inflicting such wholesale destruction. Thirdly, the 

 smuts and rusts, or technically the UstilaginecB and the UredinecB ; and 

 fourthly, the obscure and mysterious group of Bacterial, or Microbe 

 diseases, only recently taken into account. 



Leaf-spotting is caused chiefly by small parasitic fungi, which consist 

 of small flask-shaped conceptacles, called perithecia, enclosing minute 

 spores, or conidia, which are expelled from an opening at the apex when 

 mature, often in the form of tendrils, in which the spores are held 

 together for some time as if by some tenacious gluten. These perithecia 

 are usually gregarious, developed beneath the cuticle, on discoloured spots, 

 such discoloration being caused chiefly by the mycelium of the peri- 

 thecia. Each spot may contain three or four, or from thirty to forty 

 perithecia, each so minute as to appear to the naked eye as the smallest 

 black dot, sometimes almost if not quite inconspicuous. In the smaller 

 group including " anthracnose," the perithecia are spurious and the spores 

 are produced within similar- shaped cells, being extruded when mature 

 from the perforated or ruptured apex. 



The simplest form of leaf-spot is Phyllosticta, in which the spores are 

 minute, and chiefly more or less elliptical. No British species has yet 

 been met with on cultivated Caryophyllacece, although Phyllosticta 

 Dianthi occurs in Belgium on Sweet William and in Britain on wild 

 plants (fig. 1),* and Phyllosticta tenerrima in Canada on Saponaria. 

 Another genus is Ascochyta, in which the chief difference lies in the 

 spores being divided by a transverse septum into two cells. Ascochyta 

 Dianthi is not uncommon in Britain, on leaves of Dianthus (fig. 2), as 

 well as in the Netherlands and Germany. Ascochyta Saponarice is at 

 present confined to Germany. In the genus Septoria the spores are 

 elongated, often very long and slender, nearly thread-like, and mostly 

 septate. Septoria Diayithi, on Sweet William, is European (fig. 3), but 

 not British. Septoria Lychnidis occurs in Britain, France, and Italy on 



* In this paper the numbers refer to the several figures on the coloured plates. 



