NEMATOTOXIC EFFECTS OF A HOT WATER EXTRACT OF WASTE ASPARAGUS ROOTSTOCKS ON ROOT-LESION NEMATODE (PRATYLENCHUS PENETRANS)

Because asparagus (Asparagus officinalis) rootstocks contain anti-nematode substances, incorporating them into agricultural fields can control populations of root-lesion nematodes (Pratylenchus penetrans) during subsequent crop cultivation. However, direct incorporation of waste rootstocks risks transmission of soil diseases. We hypothesized that this could be avoided by using an aqueous extract from asparagus roots in place of the roots themselves. Here, we tested the nematotoxicity of the extract in comparison to cut roots, assayed for inter- and intra-individual variations in nematotoxicity, explored possible variations caused by cultivar type (‘UC157’ and ‘Harumurasaki’) or region (Gunma or Fukushima Prefectures) of plant origin, and investigated differences between extracts made from full and empty rootstock. We found that aqueous extracts were almost as nematotoxic as cut roots. Nematotoxicity did not vary greatly among plants, or between the roots and rhizomes of plants. Although the ‘Harumurasaki’ cultivar appeared to have slightly higher nematotoxicity, there were no major differences between ‘UC157’ cultivars from the two different prefectures. Finally, extracts made from full and empty roots had similar nematotoxicity. Cumulatively, these results indicate that aqueous extracts from asparagus rootstocks offer a way to control nematode populations without risking transmission of soil disease. Furthermore, because this method uses products that are otherwise regarded as waste, it offers a solution to an important agricultural waste disposal problem.