24 BULLETIN 1347, U. S. DEPARTMENT OF AGRICULTURE 
and unsprouted seeds were removed from the soil and data taken 
on infection. There was no indication that any seedlings had been 
killed by the fungus, and no blighting had taken place on any of 
the plants. In all cases seed germination was about 95 per cent. 
TABLE 3.—Infection in certain varieties of wheat seedlings grown in soil 
inoculated with a pure culiure of Helminthosporium sativum 
[Data based on the degree of injury to the underground portion of the stem and on the number of plants 
infected] 
= Percent- = Percent- 
Pee Number = 1s Number 
Variety age of Variety age of 
: ian J ABH ara AL Sin Bd 
Wrarcuise © = .2 2 sees eee Le 146 90.1. || Harvest Queen) yf) 22 188 59.0 
Dawson Golden Chaff_-_--___- 109 it. 0 NRedMiny 22 eae eee 173 55.0 
Turkey (Wis. Ped. No. 2)_---- 181 67.2 4) Wind (Chief... ae SEE 147 52.5 
ReduWavGn tee eee eee 156 66. 4 | 
The writer has sown a few varieties of spring wheat and barley 
near Granite City, Ill., on soil naturally infested with Helmintho- 
sporium sativum, and portions of the data on these varieties have 
already been published (44). In general, Marquis wheat seems to 
be more susceptible to infection by H. sativwm than any of the 
winter varieties tested. This is shown in Table 3 and in data pre- 
viously published (45). These last-mentioned data also indicate 
that Hanna barley is more susceptible to infection than Harvest 
Queen wheat but less so than Marquis. Field experiments also have 
indicated that spring wheats and barleys develop more severe in- 
fections than winter wheats. However, part of the differences in 
susceptibility noted in the field can undoubtedly be accounted for on 
the basis of temperature and soil-moisture differences during the 
winter and spring growth periods. 
LIFE HISTORY OF HELMINTHOSPORIUM SATIVUM 
No perfect fruiting stage has been discovered in connection with 
Helminthosporium sativum. The organism produces conidia pro- 
fusely on the host and on most culture media. It thrives as a 
saprophyte on straw and old stubble and sporulates abundantly on 
these materials. Owing to the profuse development of conidia it is 
very difficult to determine whether the mycelium survives the winter. 
Numerous soil-inoculation experiments in the fall at Madison, Wis., 
showed that the organism survives the winter in the soil and will 
produce infection on wheat plants in the spring. 
The fungus lives for long periods under laboratory conditions. 
The writer has carefully plated infected barley seed over 2 years 
old and found the mycelium still alive in a high percentage of the 
seed. Germination tests of conidia from barley leaves which had 
been stored in a herbarium at Madison, Wis., for nearly three 
years also have been made by him, and it has been found that a low 
percentage of the spores germinated on agar plates. 
The writer has reported previously (45) that the conidia of 
Helminthosporium sativum remain in a dormant state when placed 
in a large quantity of water. It has been found that the conidia 
will germinate freely when removed from the water and put on agar 
plates or in small quantities of water, such as a hanging drop. The 
writer has had tap-water and distilled-water suspensions of this 
