Submitted to: Plant Disease
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/24/2003
Publication Date: 3/15/2004
Citation: Bonde, M.R., Berner, D.K., Peterson, G.L., Olsen, M., Cunfer, B., Sim, T. 2004. Survival of Tilletia indica teliospores in different soils. Plant Disease. 88:316-324. Interpretive Summary: Karnal bunt of wheat is a minor disease resulting in small reductions in grain quality and yield. However, because of its high international quarantine status, it has the potential for causing large economic losses to the U.S. Seventy-seven countries currently have restrictions on importing wheat from areas within the U.S. where the disease occurs. The research conducted for this study suggests that some areas of the U.S. have soils that are not conducive for long-term survival of Karnal bunt spores. It is hypothesized that in localities where the environment rarely is conducive for infection of wheat plants, the rate at which the pathogen populations lose viability in soil is greater than the generation of new spores. The pathogen therefore could permanently become established in these soils. This information can be used to refine maps that have been drawn to predict where Karnal bunt might become established.
Technical Abstract: Karnal bunt (KB) of wheat, incited by Tilletia indica, is a minor disease typically resulting in small reductions in grain quality and yield. However, because of its high international quarantine status, it has the potential to cause large economic losses to wheat exporting countries. In order to determine the potential for T. indica to spread and become established, a teliospore longevity study was initiated in field plots in four states. We determined that teliospore longevity varied greatly among soils. The rate of decline in viability was greatest for a soil from Kansas, followed by a soil from Maryland. Because the rapid loss in teliospore viability occurred in the two soils both in the laboratory and in the field, we hypothesize that the soil itself, irrespective of weather or climate, was responsible. We also hypothesize that in localities where the environment rarely is conducive for infection of wheat plants by sporidia, and where there is a rapid decline in teliospore viability in soil, the pathogen is incapable of sustaining itself, or at most causes sporadic and minor disease.