84 BULLETIN 1347, U. S. DEPARTMENT OF AGRICULTURE ~ 
Jsolation studies by Beckwith (4), Bolley (70), and Stakman 
(65) have shown that several other genera of fungi are associated 
with culm rots and root rots. Among these genera species of Colleto- 
trichum, Alternaria, and Macrosporium seem to be common, and 
the studies of these workers indicate that some of these fungi are 
parasitic on wheat seedlings. Recently Hungerford (33) reported 
Sclerotium rhizodes associated with a wheat disease occurring in 
Idaho. The field and plant symptoms associated with this trouble 
seem to be similar in some particulars to those manifested by the 
foot-rots, and it may be that this organism will be found to cause 
the disease in question. According to Haskell and Wood (27, p. 207), 
B. L. Richards has reported to the Office of Plant-Disease Survey 
that a species of Rhizoctonia is associated with wheat foot-rot in 
Morgan County, Utah. There is no statement, however, as to the 
pathogenicity of this fungus on wheat. 
DISCUSSION 
The foot-rot diseases of wheat are rather widespread in America, 
causing crop losses of economic importance in several of the principal 
wheat districts. Although the studies which have been carried on by 
numerous investigators have thrown considerable ght on these 
diseases, it is certainly evident that they have done little more than to 
assist in defining some of the problems and to convince some of the 
students of the soil and of cereals that soil fungi are in many cases 
the limiting factors in wheat production. As the study of these 
problems progresses, it becomes increasingly evident to the writer 
that the general suggestion made by Bolley (70) that the low wheat 
yields in many of our principal wheat districts can not be accounted 
for chiefly on the basis of low soil fertility deserves very careful 
consideration. It seems evident that any constructive program of 
investigation for the purpose of increasing wheat yields must include 
a study of wheat diseases caused by the parasites infesting the soil. 
In attacking plant-disease problems it is generally accepted that 
the causal agents must be studied independently under controlled 
conditions in order that an accurate understanding of the problem in 
hand may be obtained. ‘This method has led to the development of 
refined laboratory methods whereby parasites may be cultured and 
kept free from contaminating organisms and whereby the environ- 
mental influences also may be kept as constant as possible or varied. 
at will when such parasites are studied independently or in relation 
to the development of disease. Although these refined methods are 
highly essential and important in connection with obtaining certain 
knowledge, it must be recognized that investigators too frequently 
are prone to confine their disease studies to these ultrarefined meth- 
ods instead of supplementing them with the somewhat less refined 
ones which are more comparable to the conditions under which the 
plant grows in nature. Several cases are on record where organisms 
have been classed as cereal parasites on the basis of inoculations made 
on plants grown in the rag-doll seed tester or in agar contained in 
test tubes. In some cases such experiments have not been followed 
up by soil-inoculation studies, or if such studies have been made they 
were of a very minor nature, and the final conclusions were based pri- 
marily on results obtained by the more artificial technique. ‘The 
writer has made use of the agar and test-tube method to a hmited 
