CERCOSPORA 489 



equally on both sides of the leaf, sporophores short, simple, 

 greyish, 30-35 x 4 /x, conidia very long and slender, 1 50-200 X 

 3 - 5 [x, rod- shaped, many-septate, hyaline. 



A disease that is very difficult to check when it once gains 

 a foothold on plants growing in a frame, on account of the 

 forcing methods practised, the crowded condition of the 

 plants, and the constantly damp atmosphere and wet soil. 

 The under leaves are attacked first, and these should be 

 removed on the first appearance of the disease. At the same 

 time the plants should be sprayed with dilute Bordeaux 

 mixture ; it is wise to spray once or twice in anticipation of 

 the disease, before the flowers begin to show. 



Mignonette leaf spot (Cercospora resedae, Fuckel) often 

 attacks mignonette, more especially when grown under glass. 

 Dry brownish spots appear on the leaves, causing them to 

 turn yellow and die. 



Conidiophores forming minute tufts on brown spots on 

 the leaf, closely crowded, simple, continuous, or sparingly 

 septate, straight below, rather wavy above, brown, 50-70 X 

 4-5 \x. Conidia acrogenous, narrowly obclavate, 4-5-septate 

 hyaline, 100-140 x 2 - 5-3 - 5 /x. 



Spraying with dilute Bordeaux mixture, as soon as the 

 disease appears, arrests its progress. 



Cercospora rubi (Sacc.) forms more or less circular, large, 

 pale coloured, dry spots on bramble leaves. 



Hyphae short, spores narrowly cylindrical, slightly tapering 

 towards the apex, slightly curved, septa several, almost 

 hyaline, 50-100 X 4*5 \><. 



Cercospora odontoglossi (Prill, and Del.) attacks Odonto- 

 glossum crispum. The leaves assume a yellowish-green 

 colour, and show blotches here and there of a greenish- 

 olive tint which become covered with a delicate mould. 

 The leaves are killed in rapid succession when the disease 

 once gains a foothold. 



Effused, velvety, olive-brown ; sporophores erect, some- 

 times forked, sinuous, 100-150X3-4 ^ ; conidia elongated, 

 narrowed upwards, 2-3-septate, hyaline then olive, 45-80 X 



4-5 l J - 



Sponging at intervals with a dilute solution of sulphate of 



copper is recommended. 



Prillieux and Delacroix, Bull. Myc. Soc. France, 9, p. 270 

 (1893)- 



