Incidence of Chalara elegans in groundnut seed samples and seed transmission of blackhull

The incidence of Chalara elegans ( =Thielaviopsis basicola ) was determined in seven commercial groundnut seed samples in the Vaalharts area of South Africa. It was demonstrated that 1.19% of the seeds were infected by the pathogen. Surface contamination of visually healthy seeds from the same samples was confirmed by testing seed washings for viable propagules of C. elegans on raw carrot dises. Naturally infected seed planted in autoclaved soil in the greenhouse resulted in 34.4% severely diseased plants. These results indicate that seed-borne inoculum may be an important factor in the transmission of this disease.