Research Bulletin (Iowa Agriculture and Home Economics Experiment Station)


Injury by Basisporium gallarum is associated with cessation of translocation within the corn plant. It occurs at the time of germination, after normal maturity, and when plants die prematurely from cold or other causes.

Basisporium-infected seed dies within a few days after it is planted in soils slightly below the temperature range for germination. The organism kills the germ before active translocation sets in. Active translocation, in this case, means germination and germination marks a change in the embryo from neutral to acid reaction. Acid reaction in the cob was shown to be correlated with resistance to Basisporium infection. Therefore, the fact that the germinating kernel becomes resistant at the same time that the embryo becomes acid may mean that there is a similar correlation between acidity and resistance in the seed as has been shown between the acidity of the cob and resistance to Basisporium ear infection. Therefore, good field stands are correlated with warm soil temperatures which promote rapid germination and poor field stands with cold soil temperatures which make germination slow.

Seed treatments are most beneficial under conditions suitable to greatest injury by the organisms, namely, cold soil at time of germination.

Seed corn strains which germinate readily at low temperatures (below 11°C.) . are injured little by Basisporium gallarum. Seed corn strains requiring high temperatures (above 11°C.) for germination are severely injured by B. gallarum.

Experiments on artificial inoculation of corn ears with Basisporium gallarum indicated that when natural inoculum was widespread the number of infected ears was not significantly increased by artificial wound inoculations. With or without artificial inoculation, susceptible ears became infected and the resistant ears did not. A similar experiment in a year when natural infection was much less (6 percent in check), gave an increase (9 percent in inoculated) following artificial inoculation.

The resistant ears are those having high hydrogen ion concentration in the cobs. The susceptible ones are those having low hydrogen ion concentration in the cobs.

Cob reaction is an inherited character and promises a means of more easily breeding strains of corn resistant to Basisporium ear-rot.

The correlation between the ability to germinate at low temperature and the resistance to injury by the organism is the basis for breeding strains of corn resistant to seed rotting by Basisporium gallarum at time of germination.



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