262 
Massee, 1912 (127), says that the mycelium forms a thin felt on 
the stem and sheaths and that a black superficial mycelium is also char- 
acteristic. Oats and wheat inoculated when about an inch high with 
Ophiobolus graminis were yellowed and drooping in six weeks, with 
characteristic mycelial infection. Bromus and Agropyron are also in- 
fected. Prunet, 1913 (138), concludes that either Ophiobolus graminis, 
O. herpotrichus, or Leptosphaeria herpotrichoides can cause the disease, 
and says that the name pictin is thus applied to three diseases with the 
common character of stem-blackening, and that each should be studied 
separately. 
In 1913 Guerrapain and Demolon (139) (140) call particular at- 
tention to this disease following a mild winter. Voges, 1913 (143), in 
a very extensive article, concludes that the Ophiobolus ascospores can 
give rise to two kinds of mycelium, one of which is Fusarium rubigino- 
sum A. & W.; that the Ophiobolus mycelium is not characteristic of foot 
disease and that the specific cause is not Ophiobolus; and that the dis- 
ease has various causes, for example frost, the Ophiobolus appearing 
only after weakening due to other causes. Mangin, 1914 (158), says 
that both Leptosphaeria and Ophiobolus give a brown or black tint to the 
stem and roots. The presence of several Fusaria is also noted in connec- 
tion with this disease. Berthault, 1914 (161), says that Fusarium rubi- 
ginosum is often present and perhaps causal. Voges, 1914 (162), says 
that the conidial form is not Fusarium but is Acremonium. Spafford, 1917 
(175), suggests the name “wheat stem killer”, and says that the disease 
may be recognized at the base of the stem, which is “covered with a 
brownish powder or stained brown.” He regards this character as im- 
portant in distinguishing this disease from the results of climatic action 
due to drying out, in which cases the plant is yellow throughout. He 
states that if wheat gets a good start, even in infected soil, but little 
injury follows. In 1917 (176) Ophiobolus graminis was reported on rice 
in Japan. In 1919 Brittlebank (179) lists as hosts, wheat, oats, barley, 
Hordeum murinum, Bromus mollis, B. sterilis, and Agropyron scabrum. 
In 1919 the latest paper available from Australia (178) is less definite 
as to etiology than are earlier Australian papers. 
In the voluminous mass of evidence presented in these articles cer- 
tain points stand out clear, others are far from clear. 
Points oF AGREEMENT 
1. A serious loss to the wheat crop in many countries arises from 
a diseased condition of the wheat plant which is aptly called foot-rot, 
black-foot, or black-stem, or, by the French, piétin, though known by 
many other names. 
2. This disease is characterized by a darkening, blackening, or rot- 
ting of the lower stem, usually the first internode above the roots. 
3. The disease always occurs in spots in the field. 
