FUNGOID PESTS OF CULTIVATED PLANTS. 21 



€. grata, C. orientalis, and C. pnberula, -whilst JEcidium otagense is 

 confined to New Zealand. 



Leaf-spot is also common, with Phyllosticta Vitalba (Cooke), formerly 

 included hy error under Septoi'ia Clematidis, on our indigenous species. 

 Phyllosticta Clematidis in Canada; Phyllosticta corrodens upon Clematis 

 Vitalba in Italy, in company with Phyllosticta bacteriosperma. 



One form of leaf-spot, with bicellular conidia, is Ascochyta Vitalba, 

 found in France. 



Of leaf-spots having long threadlike conidia Septoria ( 'lematidis is 

 liritish, as well as proper to some other parts of Europe. Septoria 

 dematidis-Flammula on C. Flammula in France ; Septoria Clematidis- 

 rectce on C. recta in Italy, as well as Septoria Flammula on C. Flammula, 

 and Septoria Viticellce on C. Viticella. To these may be added Septoria 

 Jenissensis on C. glauca in Siberia, and Septoria Jackmanni on C. Jack- 

 maun i in New York. 



Clematis White-mould. 

 Ovularia Clematidis (Chitt.). 



From Chelmsford the flowers of Clematis Jackmanni'} were sent, 

 infested with a white mould, which has been named Ovularia Clematidis 

 I Chittenden), forming whitish patches on the upper surface of the petals, 

 and may thus be described : Spots epiphyllous, white, conspicuous, circular 

 or sub-circular, from 2 to 4 centimetres in diameter. Mycelium colour- 

 less, branched, creeping. Fertile hyphse erect, simple (40-60 yu x 7 fj), 

 two or three times septate. Conidia hyaline, solitary, or mostly so, 

 cylindrical, with rounded ends (28-42 x 14-10 /x), smooth. (See fig. 4.) 



This species occurred in September, 1903, and diners from all 

 described British species in the large conidia, which sometimes give 

 indications of being shortly catenulate. 



Card. Chron. Oct. 31, 1903, p. 299 ; Joum. B.H.S. xxviii. (1904), 

 p. clxxvii, fig. 176. 



Crucifek Rot-mould. 

 Peronospora parasitica (Pers.), PI. VI. fig. 30. 



There are but few parasites on garden Crucifers, but this is sufficiently 

 destructive to the foliage of Wallflowers, Stock, and some other garden 

 flowers to make up for the deficiency. 



It occurs in whitish mouldy patches on the leaves and inflorescence. 



The mycelium is profuse, thick, and very much branched, from which 

 arise the erect threads, which are also rather thick, soft, and flexile, from 

 five to eight times branched, in a forked or trifurcate manner, the ultimate 

 branches awl-shaped and curved, bearing the broadly ellipsoid conidia 

 (20-22 x 16-20 /.<). 



The resting spores, which are seated upon the mycelium in the; stems 

 and branches of the host, are globose (26-10 /< diam.), either smooth or 

 rugged, and of a yellowish or tawny colour. 



For details of life history and development of the rot-moulds see 

 Introduction, p. 2. 



Diseased parts should be burnt to destroy resting spores. 



Sacc. Syll. vii. 830; Cooke 31. F. t. 14, 1.265', Hdbk. No. 1778; 

 Mass. PI. Dis. 79, 855 ; Mass. JJ. F. 119, f. 15, k6, 12!>. 



