422 DISEASES OF CULTIVATED PLANTS 



of Bordeaux mixture. A stronger solution injures the foliage. 

 Badly attacked plants should be burned. 



Giissow, Journ. Bd. Agric.^ 1908, p. in. 



Carnation leaf disease. Professor Potter has given an 

 account of the ravages of Septoria dianthi (Desm.) on the 

 leaves of cultivated carnations. The disease is recognised by 

 the bleaching of the part attacked, which changes to a straw- 

 colour and of a dull surface. Such discoloration is not 

 localised, but extends from the point of infection along the 

 whole surface of the leaf to the tip. The tissue becomes 

 much shrunken and the leaf curls longitudinally. Full-grown 

 leaves are most frequently attacked, but young leaves by no 

 means escape ; the nodes of the flowering-stem also suffer. 



The fungus is a serious pest, and is well known to culti- 

 vators of carnations and pinks in Europe, South Africa, 

 Australia, and the United States. It also occurs on several 

 wild caryophyllaceous plants in Europe. 



Perithecia immersed in the leaf, being produced in the 

 substomatal cavities, with the mouth projecting above the 

 surface of the epidermis, blackish ; spores extended in a 

 tendril-like, mucilaginous mass, hyaline, long and narrow, 

 usually slightly curved, both ends obtuse, sometimes i -septate, 



30-45 X4-4'5 /* 



Prompt removal of infected leaves, accompanied by spray- 

 ing with potassium sulphide is recommended. 



Potter, M. C., Journ. Roy. Hort. Soc., 27, p. 428 (1902- 



Brown spot of chrysanthemum leaves. This disease, 

 caused by Septoria chrysanthemella (Sacc.), is well known on 

 the Continent and in the United States. It has also been 

 recorded in this country by Salmon. The symptoms are the 

 presence of brown spots on the leaves. Such diseased leaves 

 usually become crumpled at the edges, and fall prematurely, 

 the plant being thus not only disfigured, but also weakened in 

 growth. 



The subglobose, minute perithecia are immersed in the 

 substance of the diseased spots, and appear as black points at 

 the surface. Conidia hyaline, filiform, septate, 40-70 X i '5-2 /x. 



Bordeaux mixture is recommended ; but the unsightly 

 appearance of this substance on the plants can be avoided by 



