12 BULLETIN 1210, U. S. DEPARTMENT OF AGRICULTURE. 
from this source would disappear in a short time after applying th 
manure. ‘3 
Steglich (356) agrees that danger from spores introduced with 
stall manure lasts but a few days, because, as he asserts, manure | 
acts as a stimulant to germination and thus causes the spores quickly 
to become innocuous in the absence of a host plant, as continuous 
reproduction of conidia does not take place in the soil. A microscopic 
examination of spores evacuated by swine showed 75 per cent loss of 
viability. Spores placed in a small sack and buried in a manure pile 
for 193 days had practically all germinated and become innocuous 
When these were mixed with water and sprayed on seed wheat they 
apparently caused the appearance of three bunt heads in 15 square 
meters of field area. 3 
Appel and Riehm (20) are confident that in no case do bunt spores — 
in the soil survive the winters of northern Europe. At that time they — 
believed that infection from spores in the soil seldom, if ever, occurs. — 
Honcamp, Zimmerman, and Schneider (1/67) conducted some 
experiments to determine: (1) The toxic effect of bunt fed to animals, — 
(2) the effect on the spores produced by passing through the animal, 
and (3) the probability of wheat infection from manure-borne spores 
or from spores reaching the manure after its evacuation. They found — 
that spores passing through the animal had in great part lost their 
viability, but that this loss was less pronounced in the case of swine 
than with other animals. 
Appel and Riehm (27) conclude that infection of wheat by way of 
stall manure containing spores which have passed through the 
digestive tract of animals is so slight as to be disregarded in practice. 
Thus their results in general agree with those of Tubeuf, but are not 
in entire accord with the conclusions of Steglich. Although infection 
from spores mixed with the manure after evacuation does obtain, it 
is, nevertheless, slight in comparison with that resulting from spores 
adhering to the seed. Regarding the duration of bunt viability in 
the soil, Appel and Riehm maintain that in uninjured bunt balls the 
spores can lie in damp soil for some time without germination. Thus 
infection from such balls might result, provided they are able to 
withstand external influences and remain intact until broken by 
tillage or seeding operations. The spores resist cold, and in dry 
storage they lose but little viability in two vears. Appel and Riehm 
further state that the conidia are resistant to weather influences so 
long as the soil contains sufficient moisture, but that they are de- 
stroved by dryness. An infection due to such soil infestation would, 
therefore, be dependent on the soil-moisture factor. 
The above conclusions regarding the life of the conidia in the soil 
would seem to support Brefeld’s theory of the continuous saprophytic 
life subject only to moisture relations. It is the opinion of the 
writers that Honcamp and others are mistaken in this conclusion 
and that they have overlooked a most important factor, i. e., the 
organic flora of the soil. The studies of the writers have consistently 
shown that Tilletia grows readily enough in soil or on nutrient media 
as long as conditions are such as to prevent its being overrun with 
other organisms. 
Concerning the possibility of a crop becoming infected by means 
of wind-borne bunt spores from hiedhine machines, there is little to 
be found in the literature. It was first suggested by Saunders, 
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