Suppressive impact of glucosinolates in Brassica vegetative tissues on root lesion nematode Pratylenchus neglectus

The potential of tissue amendments from a variety of wild and cultivated Brassica spp. to kill the root lesion nematode (Pratylenchus neglectus) in soil was assessed in laboratory experiments. Soil amended with leaf tissues was highly nematicidal, killing 56.2-95.2% of exposed nematodes. Amendment with root tissues was less effective, causing 0-48.3% mortality. Little of the suppressive impact by leaf tissues could be related to either total contents or any individual glucosinolate as determined by HPLC analysis. While the levels of total glucosinolates within root amendments had a nonsignificant relationship to nematode mortality, levels of 2-phenylethyl glucosinolate within root amendments significantly correlated with nematode suppression (P < 0.001). Amendment of soils with equimolar levels of purified 2-phenylethyl isothiocyanate resulted in comparable levels of nematode mortality, suggesting that 2-phenylethyl glucosinolate has a role in the suppressive impact of Brassica spp. root tissues.