106 DISEASES OF GLASSHOUSE PLANTS 
to cultural conditions and an avoidance of high tempera- 
tures and excessive watering, combined with careful 
selection of cuttings, are usually sufficient to prevent the 
disease from reaching abnormal conditions, so that 
spraying should not be necessary. 
Septoria Leaf Spot of the Carnation.—This disease is 
caused by Septoria dianthi Desm., which produces light 
brown areas on the leaves and stem of the carnation. 
Most commonly the lower portion of the leaves, especially 
the sheathing base, is attacked, and this causes the leaves 
to bend downwards. Diseased leaves also frequently 
become much shorter and curl longitudinally. Diseased 
areas on the stems are generally found between the nodes. 
When the tissue has died as the result of the fungus 
attack, numerous tiny black spots may be seen scattered 
over the surface. These are the pycnidia or fruiting 
bodies, which contain masses of long, narrow, septate 
spores. 
Under normal glasshouse conditions the disease is 
rarely serious, being checked by efficient ventilation and 
careful watering. Spraying with liver of sulphur or dust- 
ing with sulphur powders is recommended as a means of 
control. . 
Leaf Mould of the Carnation.—The symptoms of the 
disease, which is caused by Heterosporium echinulatum 
Berk., are recognized by the production on the leaves of 
small, pale grey spots about an eighth of an inch in 
diameter. The spots become covered with a dense mat 
of fungal growth, which assumes a grey and finally a light 
brown colour. Numerous olive-coloured spores covered 
with tiny warts are produced on the spots. The method 
of control recommended is the same as for “ leaf spot.” 
Macrosporium Leaf Spot of the Carnation.—Some 
varieties of carnations suffer from a disease of the leaves 
and stems due to Macrosporium diantha Stevens and Hall. 
Pale grey, circular or elongated spots, the centres of which 
