642 
Journal of Agricultural Research 
VoLXXIV,No .8 
APPEARANCE OF AFFECTED PLANTS 
Although the S3ntnptoms produced by a species of Helminthosporium 
on some particular host are generally quite well defined, the different 
members of the genus considered collectively bring about a considerable 
variety of changes. These may be briefly considered under a number of 
categories. 
SPOTBI^OTCH, FOOTROT, EYESPOT 
Perhaps the most easily recognized type of lesion is represented by the 
discoloration resulting from the attack, for example, of Helminthosporium 
sativum V. K. & B. on barley (Hordeum spp.), wheat (Triticum spp.), 
and quack grass' {Agropyron repens [L.] Beauv.). Here each foliar 
infection produces a fairly well-defined, more or less longitudinal spot 
ranging in color from light brown to nearly black. An entirely similar 
type of leaf injury is characteristic of the diseases of Kentucky bluegrass 
(Poa pratensis L.) and of barnyard grass {Echinochloa crus-galli [L.] 
Beauv.), attributable to two congeneric parasites that are newly described 
in this paper as H, vagans and H. monoceras, respectively. When the leaf 
sheaths also are affected, the discoloration often becomes increasingly dif¬ 
fuse downward, so that the base of the stem may be quite uniformly dis¬ 
colored—a condition that in the case of wheat, where it is usually com¬ 
plicated with more or less injury to the roots, has become widely known as 
footrot. Similar dark foliar spots characterize the incipient attack of 
H, leersii Aik, on white grass {Leersia virginica Willd.), of H, giganteum 
H. & W. on goose grass (Eleusine indica [L.] Gaertn.), and Bermuda 
grass (Cynodon dactylon L.), and of H, oryzae B. de H. on rice {Oryza 
saliva L.)* Later, however, the central areas lose their dark color, the 
older and larger spots being finally represented by a dark brown ring 
surrounding a central straw-colored area. The term ‘‘eyespot,'' which 
has been applied (73)^ to a disease of sugar cane (Saccharum officinarum 
L.) caused by H, sacchari ButL, is perhaps most accurately descriptive 
of the latter type of foliar lesions. 
netbeotch 
A second category of discoloration very characteristic, though less 
common, is caused by Helminthosporium teres Sacc. on barley, as well as 
by a fungus on Festuca elatior L. described in this paper as H, dictyoides. 
The affected leaves, while still green and living, show abundant brownish 
discoloration in irregular pattern, within which may be recognized a net¬ 
work of darker longitudinal and transverse linear streaks. With the 
withering of the leaf these reticulate markings become less pronounced, 
and are finally more or less completely obliterated. 
stripe 
Helminthosporium gramineum Rabh. causes an unusual type of injury 
to barley, the leaves previous to heading time becoming variegated with 
yellow bands extending frequently the whole length of the leaf. On 
the premature death of the plants the foliar organs split along these 
longitudinal markings, giving them a ragged or shredded appearance. 
This type of injury has been shown to be contingent on continued 
development of the parasite in the growing tissues in a manner not 
unlike the development of certain smut fungi. 
• Reference is made by number (italic) to “ literature cited" pp, 731-739. 
