Effects of vermicompost water extract prepared from bamboo and kudzu against Meloidogyne incognita and Rotylenchulus reniformis

A series of experiments in laboratory, greenhouse, and field were conducted to compare the nematode suppressive effect of vermicompost tea (VCT) prepared from vermicompost with moso-bamboo (Phyllostachys edulis (Carrière) J. Houz.) and kudzu (Pueraria lobata (Willd) Ohwi) as feed stock (weed VCT) to that prepared from vegetable food waste (vegetable VCT) against Meloidogyne incognita and Rotylenchulus reniformis. Two laboratory trials were conducted by incubating eggs of M. incognita and R. reniformis in weed VCT or vegetable VCT over 1 wk. These trials revealed that although both VCTs suppressed M. incognita egg hatching compared to water control, only weed VCT suppressed R. reniformis egg hatching. In addition, both VCTs suppressed the mobility of second stage juveniles (J2s) of M. incognita equally compared to water control though suppression from weed VCT performed inconsistently between the trials. When root penetration of M. incognita on cucumber drenched with VCT on one side of a split-root system in a greenhouse sterile sand-soil mix was examined, weed VCT suppressed root penetration of M. incognita on the other side of the root in two trials, but vegetable VCT was only effective in one trial. However, both VCTs did not suppress R. reniformis root penetration. When the effect of the VCTs was examined in two cowpea (Vigna unguiculata) field trials, drenching of VCTs did not affect cowpea growth and yield, but weed VCT reduced root-gall index compared to the water control in both trials. Although both VCTs did not reduce the number of M. incognita and R. reniformis in soil, weed VCT did increase omnivorous nematodes in the second trial, indicating a gradual improvement of soil food web structure through VCT drenching over time. Overall, performance of weed VCT was more consistent than vegetable VCT for plant-parasitic nematodes suppression.