FOOT-ROT DISEASES OF WHEAT IN AMERICA 11 
Waters (73), working in New Zealand, demonstrated the patho- 
genicity of the fungus by applying pure-culture material to wheat 
plants growing in tubes of sterilized soil. Kirby (37) and Davis, 
working in this country, have found O. graminis pathogenic on 
wheat and capable of producing the symptoms of take-all. 
HOST RANGE OF OPHIOBOLUS GRAMINIS 
In Australia (42), New Zealand (72), Japan, (31), and France 
(25) this parasite attacks wheat, rye, and barley. McAlpine (4/) 
states that in Australia the fungus occurs on Bromus sterilis, an in- 
troduced grass, and Darnell-Smith and MacKinnon (16, pp. 25-27) 
say that the fungus also occurs on Hordeum murinum. According 
to Waters (72), in New Zealand the fungus has been found to attack 
H. murinum, B. sterilis, and Agropyron repens. In Japan Hori 
(31) reports that the organism also parasitizes wet-land rice. In 
England the fungus has been reported frequently on wheat and oats, 
and it has been found on oats in Australia, but from the literature 
and from observations made in America it is evident that oats are 
not seriously injured by this parasite. In fact, Sutton (68) claims 
that under Australian conditions oats are practically immune from 
the attack of this fungus and that this crop assumes an important 
place in rotations on soils infested with the parasite. 
In America Ophiobolus graminis has been found to occur naturally 
on wheat, rye (37), Agropyron repens (37), Bromus secalinus (61), 
Chaetochloa geniculata (61), Festuca octofiora (61), F. elatior (61), 
and Hordeum pusillum (61). .Kirby (37) has artificially inoculated 
several wild grasses growing under greenhouse conditions and found 
that a number of species are susceptible to Ophiobolus infection. Of 
the 48 grasses studied just half the species were susceptible. Six 
common species of Agropyron were inoculated, and all became in- 
fected. According to Kirby’s data A. repens developed the most 
severe infection of all the wild grasses inoculated. On the whole, 
these inoculation tests indicate that many of our most widely dis- 
tributed wild grasses may play an important part in carrying O. 
graminis from one season to another, thus materially complicating 
any control program. 
LIFE HISTORY OF OPHIOBOLUS GRAMINIS 
As pointed out by Lindau (40) and Kirby (37), the complete life 
cycle of this parasite is not known with certainty. Several workers 
claim to have found a conidial stage, but this has never been proved 
definitely. Mangin (50) thought the conidial stage to be Coniospo- 
rium rhizophilum, but his evidence was based on the mere association 
between the latter form and Ophiobolus graminis on diseased wheat 
plants. McAlpine (4/7) found an undescribed pycnidial form asso- 
ciated with O. graminis which he says appeared to be the pycnidial 
stage of the latter organism. McAlpine described the pycnidial form 
and named it Hendersonia graminis n. sp. Subsequently Saccardo 
and D. Saccardo transferred the species to the genus Wojnowicia, 
and thus the name became Wojnowicia graminis (McAlp.) Sacc. and 
D. Sace. This fungus has been found associated with O. graminis in 
this country, but, as pointed out by McKinney and Johnson (47), the 
