Abstract
Pomegranate is one of the most popular fruit trees cultivated in Taif, where special variety called Taify pomegranate is well known. Root-knot nematodes are the most damaging plant parasitic nematodes in pomegranate. The effect of five medicinal plant extracts i.e. colocynth (Citrullus colocynthis), marigold (Tagetes erecta), rosemary (Rosmarinus officinalis), thyme (Thymus vulgaris) and ashwagandha (Withania somnifera) as well as entomopathogenic nematodes i.e. Steinemema spp. and Heterorhabditis spp. and their symbiotic bacteria i.e. Xenorhabdus sp. and Photorhabdus sp. against Meloidogyne incognito infecting pomegranate under greenhouse condition was evaluated. Results indicated that colocynth extract significantly surpassed all other treatments in improving total plant fresh and shoot dry weights with increase percentage values of 126.6 and 140 %, respectively comparing to nematode alone, whereas, marigold extract was the best treatment in suppressing nematode development. Steinernema spp. improved plant growth parameters; however, its symbiotic bacteria Xenorhabdus sp. showed the highest nematicidal properties with reduction percentages of galls and egg-masses numbers averaged 97.9 and 95.8 % respectively.