230 ILLINOIS ACADEMY OF SCIENCE 
PHYLLACHORA AS THE CAUSE OF A DISEASE OF 
CORN, AND A GENERAL CONSIDERATION OF 
THE GENUS PHYLLACHORA 
Nora E. DALBey, UNIVERSITY OF ILLINOIS 
During the summer of 1915, F. L. Stevens noted in Porto 
Rico, the occurrence of an apparently undescribed disease of 
corn, which was widespread and was found in almost every 
field examined. To what extent crops are damaged by the 
disease is not known, but since the fungus attacks the leaves of 
corn before the grain is mature, and since the leaf may be in- 
fected to such extent that ten per cent of its area is destroyed, 
considerable damage must result from the presence of the 
the fungus. The present study is based entirely on herbarium 
material collected in 1915, and all efforts to culture the fun- 
gus have given negative results. 
THE DISEASED SPOTS 
The disease appears as well defined, conspicuous, sub-car- 
bonaceous spots, averaging about 1.2 mm. in diameter, and 
slightly roughened on the surface. A sharp line of demarcation 
separates the healthy from the diseased tissue. The infection is 
local and so far as observed is confined to the leaf and the leaf 
sheaths. The spots, due to the formation of fungous stromata 
in the infected tissue, are scattered irregularly over the entire 
leaf and are visible from both upper and lower surfaces. They 
usually are larger and more conspicuous on the upper surface. 
In form they are round or elongated and have an irregular 
margin. The stromata tend to grow along a _ vein, 
sometimes to a distance of a cm. or more, although the more 
characteristic spot is round to ovate. The spots are small and 
numerous or comparatively large and sparsely distributed, and 
in either case are usually surrounded by a narrow yellowish- 
brown halo which is more evident on the under side of the 
leaf. 
A fungus which appeared to be Scolecotrichum gramims 
was commonly present on the Porto Rican specimens. This 
fungus causes dark spots due to dense mycelium and olive 
brown conidia and is surrounded by a conspicuous light brown 
halo. When spots due to the disease which is the subject of 
