Basisporium gallarum was first found on corn from Bulgaria in 1911 by Bubak and by Arzberger in Ohio in 1913. Coniosporium gecevi Bubak is identical with Basisporium gallarum Moll. The common name of Basisporium dry rot is suggested for the disease caused by this organism.
The dry rot of corn, caused by this fungus, was very prevalent in Iowa in 1923, causing an average damage to the crop of 9.1 percent, while in a few fields from 50 to 60 percent of the ears were infected. The damage consists of moldy and light ears, reduced stand and weak plants the succeeding year.
Heavy precipitation in August and September, when the crop is maturing, favors the development of the disease. Studies to date indicate that Basisporium dry rot is markedly dependent upon excessive moisture conditions when the crop is maturing, for its destructive development.
Basisporium gallarum attacks the shanks, husks and stalks of corn. The shanks particularly are weakened and break easily. On the ears the fungus is visible at the butt and base of the kernels. The black spores of the fungus can be readily seen with the unaided eye. The kernels are affected in varying degree, some only slightly, while in others the embryo is killed.
The spores germinate poorly or not at all in water. They germinate readily in tomato or orange juice. Such juice neutralized to litmus failed to produce germination. Plant tissues in the same atmosphere with the drop cultures also stimulate germination.
This action is due to the CO2 given off by the tissues. Carbon dioxide in small amounts produces a like effect.
'fhe maximum, optimum and minimum temperatures for spore germination are 35° C., 25° C., and 15° C., respectively. The optimum temperature for mycelial growth is 25° C., tho good growth takes place between 20° C. and 35° C.-40° C. and 10° C. inhibit growth. Sporulation may take place between 20° C. and 35° C. The fungus readily winters over in its conidial stage.
Basisporium gallarum grows well on a wide range of media, but prefers especially media rich in nitrogenous material. On the corn kernel, the fungus destroys the embryo before it does the starchy endosperm.
Corn is most susceptible to attack during time of germination of the seed and late stages of maturity.
Inoculation of growing roots and stalks yielded negative results. Basisporium dry rot does not spread readily in cribbed corn.
In 1923 early varieties became generally infected while late varieties remained free.
Durrell, L. W.
"Basisporium dry rot of corn,"
Research Bulletin (Iowa Agriculture and Home Economics Experiment Station): Vol. 6
, Article 1.
Available at: https://lib.dr.iastate.edu/researchbulletin/vol6/iss84/1