May a6, 2923 
Graminicolons Species of Helminthosporium 
655 
are reported to have appeared in a number of cases, thus presumably 
establishing its identity. Diedicke's findings were confirmed by Noack 
(p5) who, working independently, studied apparently the same ascigerous 
fungus collected on barley stubble in Hesse, Germany. Using conidia, 
ascospores, and sporulating material of host leaves, Noack secured 
infection by inoculating the first leaf of barley seedlings when it had 
attained a height of only several centimeters; and also on plants about 
4 weeks older. The symptoms induced in the young seedlings were 
systemic, whereas on the older plants local infections manifested by the 
appearance of brownish spots were obtained. 
The work of both Diedicke and Noack is open to the criticism that it 
was not done in connection with parallel infection experiments carried 
out with Helminthosporium teres, and that consequently these authors 
were, perhaps, not so capable of distinguishing between the pathological 
effects of the two related fungi as might have been desired. It may be 
mentioned that their fungus was obviously very similar to the form 
discussed in this paper as Pyrenophora teres (Died.) collected by the 
writer near Madison, Wis., where it occurred in abundance in spring on 
barley stubble apparently regardless as to whether or not the crop of the 
preceding year had been seriously affected with stripe. Recently, 
Paxton {106) has reported the occurrence of the mature perithecial 
stage of H, gramineum on two-year-old barley straw in California. 
Transfers of ascospores to com-meal agar resulted in the production of 
conidia, which when used to inoculate barley gave rise to typical stripe 
lesions. According to Van Poeteren (jop), perithecia of the parasite 
have been found on the glumes of germinated grains of barley, the seed¬ 
lings of which exhibited the symptoms of stripe. This author suggests 
incubating seed in a moist warm atmosphere for three days in order to 
determine in advance from the appearance or nonappearance of perithecia 
whether it will give rise to diseased or healthy plants. 
Of all the diseases due to species of Helminthosporium, the stripe 
disease undoubtedly has been made the subject of the largest 
amount of investigation aiming at effective methods of control. As the 
effective inoculum is presumaMy very largely,^ if not entirely, borne on 
the seed, the disinfection of the latter by the use of various fungicides 
and by the application of heat has not been without a considerable 
measure of success. Copper sulphate was found effective by Riehm 
(jjp) when applied in i or 0.5 per cent solution for 30 minutes; by Lind 
and Ravn {81) when applied in 0.5 per cent solution for 4 hours; and by 
Muller and Molz (pj) when applied in the same solution for 16 hours. 
Lind and Ravn {81) obtained satisfactory results by the application of 
formaldehyde in 0.2 per cent solution for 6 hours; Sdiander (r^p) in 0.2 
per cent solution for 30 minutes; and Johnson (70) in 0.16 per cent solu¬ 
tion for 3 hours at 20° C., in 0.25 per cent solution for 2 hours at 10°, and 
0.25 per cent solution for i hour at 25°. According to Lind and Ravn 
(^j) treatment with mercuric bichloride in o.i per cent solution for i to 2 
hours gives good results. Riehm {119) found 0.2 per cent mercury 
chlorphenol applied for 15 minutes effective. The hot-water treatment 
of seed for the control of stripe was found by Lind and Ravn {81) less 
effective than chemicals and of value only for lightly infected seed; 
Johnson {68), however, found a modified treatment with hot water 
5 hours cold, and 15 minutes at 52° C., quite valuable. A variety of 
intermittent hot-water treatments have been devised, consisting in dip¬ 
ping the seed in hot water for relatively brief periods alternating with 
