HOST-PARASITE RELATIONSHIPS OF MELOIDOGYNE TRIFOLIOPHILA ISOLATES FROM NEW-ZEALAND

Root-infecting nematodes are commonly found on white clover in New Zea land pasture where they reduce yield, nitrogen fixation, and persisten ce. The dominant root-knot nematode on white clover in New Zealand is confirmed in this study as Meloidogyne trifoliophila by isozyme phenot ype comparison with the type population from Tennessee. Results form a host differential test differed in the ranges of M. trifoliophila and M. hapla from New Zealand locations, with M. trifoliophila failing to reproduce on the standard host plants of the test. The size and chara cter of white clover root galls differ between species as M. trifoliop hila galls are large, elongate, and smooth compared to the M. hapla ga lls, which are small, round, inconspicuous, and generally have adventi tious, lateral roots. Culture and identification of root-knot nematode populations from sites in the North Island of New Zealand showed that M. trifoliophila is more widespread and abundant than M. hapla. Simil ar differential resistant and susceptible galling responses among half -sib families of white clover from a breeding program indicated that a ll M. trifoliophila populations tested were of the same pathotype. Thi s resistant material was not effective in reducing reproduction of M. hapla. Meloidogyne trifoliophila did not develop to maturity on six gr asses tested, but galls were formed on some species.