PESTS OF ORCHARD AND FRUIT GARDEN. 



19 



dots, or points, which indicate the buried receptacles which enclose the 

 fruit. 



There are two stages to this fungus : the early one in the spring 

 (Polystigmina) contains only stylospores or conidia, borne upon slender 

 threads (30 /u long). 



The autumnal fruit {Poly stigma) is not matured until after a period 

 of rest, such as is obtained by the fallen leaves upon the moist ground. 

 Then the fruit consists of sporidia (10 x6fi) which are ovate, enclosed in 

 asci, and ultimately escape when mature to reproduce the species. 



Known also in France, Belgium, Sweden, Germany, Switzerland, Italy, 

 and N. America. 



Sacc. Syll. ii. 4587 ; Mass. PL Dis. p. 135, fig. 25 ; Cooke Hdbk. No. 

 2410, fig. 383 ; Grev. Sc. Cry. Fl. t. 120 ; Tubeaf, Dis. p. 189, fig. 



Plum-tree Mildew. 

 Podosplmra tridactyla (Wall.), PI. XI. fig. 16. 



The earliest appearance of this disease on Plum and Cherry trees is a 

 whitish mealy, or mouldy, appearance on the living leaves, which thickens 

 until the surface appears as if dusted with flour or powdered chalk ; 

 ultimately little orange, and then black, dots show themselves scattered 

 over the mealy substratum. 



In its first stage the pest consists solely of the branched and inter- 

 woven mycelium of delicate threads, which produce short erect club- 

 shaped branches, soon divided into joints, which fall away from the apex, 

 when mature, as oval conidia of the Oidium type. 



Afterwards, when the black dots appear, it has passed into the 

 Erysiphc condition, the dots representing the globose receptacles enclosing 

 the fruit. These conceptacles are attached by delicate threads to the 

 mycelium, and above these, in a circle around the receptacle, are ranged 

 a circle of radiating arms or appendages, usually six or seven, standing 

 out from the sphere. These are tawny below and colourless above, 

 divided in a forked manner three or four times at the apex. Each 

 receptacle contains a Pear-shaped hyaline sac, or ascus, which holds the 

 eight ovate sporidia. The variety which occurs upon Cherry leaves 

 differs chiefly in having from eighteen to twenty appendages around the 

 receptacle. 



This is an epiphyte, and hence, like many of its kindred, may be 

 amenable to the sulphur treatment. 



Common through the whole of Europe and North America. 



Sacc. Syll. i. p. 3 ; Cooke Hdbk. No. 1916, fig. 315; Cooke M. F. 

 p. 239. 



Cherry Brown Rot. 

 Monilia fructigena (Pers.), PI. X. fig. 12. 



This is the same disease which has been referred to in connection 

 with the Apple, and also as the Apricot brown rot. However it rarely 

 attacks Cherries in this country, although prevalent in the United States. 



For fuller details see "Apricot Brown Rot." 



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