FUNGOID PESTS OF CULTIVATED PLANTS. 19 



P.eony Brown Mould. 

 Cladosporium Pceonue (Pass.), PL I. fig. 13. 



This mould was first found in Italy by Professor Passerini in 1876, and 

 has since made its appearance in this country. 



It forms broad chestnut-brown spots on the foliage, which ultimately 

 turn black. 



The threads are short and unbranched, nearly straight, and erect, 

 divided transversely into joints, and springing from an abundant creeping 

 mycelium. The threads bear at their tips the very variable conidia or 

 spores, which are commonly one- or two-septate, and sometimes two or 

 more are attached in a short chain (15- 22 x 6 n). ■ 



Although found upon still living, but faded, leaves, it is rather uncer- 

 tain whether it should be regarded as a destructive pest. Many species 

 of Cladosporium are very common on decaying plants, and for the most 

 part are simply saprophytes. The Tomato mould (Cladosporium) is 

 nevertheless a destructive parasite, and possibly others may become so. 



Spray with dilute potassium sulphide solution. 



Sacc. Syll. iv. 1729. 



Another brown mould, of a different character, Cercospora variicolor, 

 with long slender conidia (35-50x3^), has been found on Pfeony leaves 

 in the United States. This is a true parasite. 



Drooping P.eony Disease. 

 Botrytis Pceonia (Oud.), PI. VI. fig. 14. 



This white mould appear rather suddenly upon what appears to be 

 healthy-looking plants, causing them before the time of flowering to 

 become limp, the stem droops, and at length the plant dies. 



The mould may be detected on the stem of a diseased plant like a 

 delicate white mould on the blackened and shrivelled surface. 



The threads terminate in somewhat globose heads, which bear a 

 profusion of colourless elliptical conidia, or spores (16-18 x7 fi). 



Later on small black sclerotia, which are compact masses of hibernating 

 mycelium, will be found in the tissues, both above and below the ground. 



It is presumed that these sclerotia remain in the soil until the suc- 

 ceeding spring, when they may start into new life, as some of these 

 sclerotia do, under the form of a minute Peziza. 



This threatens to be a troublesome disease, and should be encountered 

 at once should it appear. All infected parts should be destroyed, so as to 

 prevent hibernation of the sclerotia. 



Mass. PL Dis. 157 ; Gard. Chron. Aug. 13, 1898, fig. 32. 



Clematis Diseases. 



The cultivated species of Clematis have hitherto been remarkably free 

 from fungoid pests, whilst our common hedgerow species has two or three 

 enemies. One or more of these may at any time make their appearance 

 in the garden, especially those in which Clematis Vitalba may have 

 secured a place. Hence we enumerate, incidentally, the; <li-< asi to u liich 

 the Clematis is liable. 



c2 



