Response of meloidogyne hapla to mycorrhiza fungi inoculation on pyrethrum

Five arbuscular mycorrhiza fungi (AMF) isolated from pyrethrum were screened in the greenhouse for efficacy in improving pyrethrum growth and in suppressing a root-knot nematode, Meloidogyne hapla. The fungi screened were Glomus spp. (isolates LM61, ML34 and ML35), Scutellospora sp. (isolate KS74) and Gigaspora sp. (isolate LM83). A 20g mixed fungal inoculum was incorporated into sterilized sand-soil mixture before transplanting 6-week-old pyrethrum seedlings. The inoculum consisted of the growth medium, spores, external mycelia and infected root segments. The plants were inoculated with 6000 M. hapla second stage juvenile (J-2) 3 months after fungal inoculation. Dry shoot weights, fresh root weights, percent root colonization by the fungi, nematode gall indices, number of eggs and females in the root system and number of J-2 in the soil were determined at the end of the experiment, two months after nematode inoculation. Glomus LM61 and Scutellospora KS74 significantly improved top biomasses of fungus-treated and fungus-nematodetreated plants. Glomus LM61was more effective (33% top biomass increase). Glomus ML34 and ML35 and Gigaspora LM83 improved top biomasses of fungus-nematode-treated plants. Scutellospora KS74 and Glomus ML34 significantly increased fresh root weights of pyrethrum by 45% and 50%, respectively. Glomus LM61, Scutellospora KS74 and Gigaspora LM83 caused 86%, 32% and 37% nematode suppression, respectively. All the fungal isolates significantly reduced the number of females and J-2. The presence of nematodes in fungus-treated plants did not affect root colonization by the fungi except in plants treated with Glomus ML34 and ML35.