834 
Journal of Agricultural Research 
Vol. XXX, No. 9 
United Fruit Co., that the conference 
should facilitate, in the best way 
possible, a satisfactory definition of 
the numerous species found on banana 
plantations. The studies made of the 
entire collection embodied species from 
all sections of the genus Fusarium, 
including important border-line strains, 
thereby making it possible to arrive 
at a uniform taxonomy of the group. 
It is believed that the main points of 
difference have been agreed upon and 
that the present paper will present a 
clearer understanding of the Fusarium 
problem from the standpoint of the 
identification of species. 
Material of each species studied and 
identified at the conference will be 
deposited in the pathological collec¬ 
tions herbarium of the Bureau of 
Plant Industry, United States Depart¬ 
ment of Agriculture, for permanent 
preservation. The cultures will be 
prepared in the manner most satis¬ 
factory for the preservation of her¬ 
barium material. Pure cultures of 
each of the species studied and iden¬ 
tified will also be placed in the bureau. 
These cultures will have substantially 
the status of type specimens. 
CRITERIA OF THE NORM 
Only a resume of the criteria of the 
norm will be here considered, since a 
complete discussion of the subject has 
appeared in former publications (5, 9). 5 
The normal condition of Fusaria from 
the standpoint of determination may 
be present in nature, but generally it 
must be produced by growing the 
fungi under pure culture conditions. 
A few Fusaria such as F. dimerum 
Penz., F. scirpi Lamb, et Fautr., F. 
culmorum (W. G. Sm.) Sacc., and some 
others may be determined directly 
from the fungus growing under natural 
conditions without resorting to pure 
cultures. Other Fusaria, which appear 
primarily in a microconidial stage 
under natural conditions and produce 
only a few sickle-shaped spores, are 
more difficult to identify. For these 
the so-called normal growth must, at 
first, be produced. It is, therefore, 
necessary to make a careful study from 
pure culture in order accurately to 
identify these organisms. Generally, 
macroconidia are regarded as the 
normal spore type. In certain groups, 
however, the microconidia may have 
definite characters, such as a pearlike 
shape or a formation in chains, which 
aid in the determination of the section 
(Sporotrichiella, Arthrosporiella) and, 
in exceptional cases, may even lead to 
the identification of species (F. poae 
(Peck) Wr., F. moniliforme Sheld., F. 
decemcellulare Brick.). 
Other normal reproductive stages, 
such as chlamydospores, by their 
presence or absence indicate the border 
of certain groups (Elegans, Lateritium). 
Sclerotia may be characteristic for 
groups (Lateritium) and even for a 
number of species (F. sclerotium Wr.). 
Color of the conidia and color of the 
aerial mycelium and stroma are further 
reliable characters for taxonomy. 
Minor characters such as mycelium, 
hvphae with specialized cells, coremia- 
like aggregations of hvphae, and aro¬ 
matic odors may also be of some 
importance for differentiation. In op¬ 
position to the norm there are abnormal 
features which might be valuable to 
mention in the diagnosis. Not so 
much stress, however, is placed on 
degenerated conditions in the life 
cycle of Fusaria. 
5 Reference is made by number (italic) to “Literature cited,” p. 843. 
