Crop failures associated with asparagus replanting have been ascribed to a combination of microbiological and chemical influences. Extracts from asparagus roots and soil were examined to locate inhibitory chemicals. Analysis of root extract fractions in a seedling assay showed that phenolic and saponin components inhibited growth but the most inhibitory material was located in the amino acid/carbohydrate fraction. However, inhibitory asparagus soil extracts did not contain significant levels of active compounds (tryptophan, caffeic acid) identified from root extracts.