LITERATURE ON BUNT OF WHEAT. 14 
ABLE 2.—Data on influence of temperature on bunt production, according to Miiller — 
: and Molz. 
Winter wheat. | Spring wheat. 
Se eNO - 
) 
Bunt heads per 
| Bunt | Average square meter. | Average 
heads tempera- fio ty viv i ener 
Date sown. | per 30 ae for | Date sown. aE | = for 
| square | 7 days e >nr| 7 days 
| meters. lovin Schlan- Red Por-| following. 
| stedter. | ‘ va 
(= 3s ‘oa ra 
bak Beard oA ©Ci 
mueeactober 5. ._..........-- ; 8, 040 | 3.31 | March 14................. 465 165 5.6 
| ae. a 2,970 | eg Ao 1 ae aaa ie 12 13 9.7 
2.13 | Apri 
PREIEL Rn pee see 17 1 7.34 
_ While the results of these spring sowings are in harmony with 
_ Hecke’s conclusions, the fall sowings appear somewhat paradoxical. 
_ At that time they challenged explanation, and to some extent they 
_ still remain unexplained. Miiller and Molz’s conclusion that lower 
_ temperatures promote bunt production is true only with limitations. 
agree that temperature at and subsequent to sowing Is an 
important factor, but are not in entire accord as to what is the 
_ optimum temperature. Hecke is positive that lower temperatures 
_ favor infection. He is supported by the field experiments of Mune- 
ain cited above. 
All these investigations seem to have failed to establish the impor- 
- tant fact that there is an optimum temperature for bunt infection 
_and production above and below which the susceptibility or liability 
_ of wheat to bunt falls off. The authors of this paper believe that 
_ their investigations, while not entirely solving the question of tem- 
i perature relations to bunt, have contributed to its solution. 
H A 
=e 
“ 
Brefeld (63) demonstrated that on a suitable nutritive substratum 
Tilletia would grow saprophytically for an indefinite period with a 
great increase of secondary conidia and eventually would produce a 
Bepore closely resembling the chlamydospore. This had been fully 
_ confirmed by the writers. but his further conclusions, 1. e., that the 
_-spores are favorably influenced and their germination promoted by 
3 assing through the digestive tract of animals, have not been con- 
' med by later investigation. Nor has it been shown that Brefeld 
was correct in assuming that infection was spread by wind dissemi- 
tation of the conidia, or that the application of infested stall manure 
to the fields would establish a permanent and increasing saprophytic 
_ growth of the bunt organism. 
_ Tubeuf (372, 574), after a comprehensive investigation of the bunt 
= problem, states his conclusion in part as follows: 
One must assume that a distribution of the bunt of wheat from plat to plat by 
_ Means of conidia in general does not take place, that spores passing through the 
_ digestive tract of animals are destroyed or injuriously affected, and that fresh stall 
manure is toxic to spores. 
In fact, Tubeuf believes that normal germination of spores does 
‘not tuke place in nutritive solutions. His experiments seem to indi- 
cate the possibility of a crop being infected through bunt-infested 
‘manure if applied iresh and very shortly before sowimg, particularly 
if the spores come from infested straw used for litter, but that danger 
