Effect of aqueous extracts and dry powder of some plants on the root-knot nematodes Meloidogyne incognita and M. javanica under greenhouse conditions

Phytochemicals of some plants are suppressive to the root-knot nematodes (Meloidogyne spp.). In this study, effects of aqueous extract or dry powder of several plants on the activity of M. incognita and M. javanica were investigated. Treatment of second stage juveniles (J2s) of the nematodes with aquatic extracts of 25 plant species under laboratory conditions showed that after 48 hours, extracts of eruca, ornamental chili pepper, tarragon, caster bean, sesame, thistle, chinaberry and dyer's crotoncaused more than 50% mortality of the J2s of both nematodes. In pasteurized‏ soil, extracts of scarlet sage and safflower seed with 78.9% and 46.9% reduction of reproduction factors (RFs) of M. incognita and M. javanica, respectively, were the most effective plants in treatment of tomato plants (cv. Early Urbana) with 13 different plant extracts. In addition, eruca and creeping thistle extracts reduced RFs of both species. None of the treatments affected fresh and dry shoot weight of tomato. In field soil, extracts of eruca and caster bean with 57.2% and 51.0% reduction of RFs of M. incognita and M. javanica in tomato plants, respectively, were the most effective extracts among eruca, caster bean, tarragonand creeping thistle plants. All treatments significantly increased the fresh shoot weight of infected tomato. In pasteurized‏ soil, scarlet sage powder with 70.3% and creeping thistle with 49.7% had the highest effect on RF reduction of M. incognita as compared to ornamental chili pepper, castor bean, chinaberry and safflower seed.