Two greenhouse experiments were conducted to determine the effect of Tylenchorhynchus zambiensis on growth of maize (Zea mays L.) hybrid MO17 x A634 and to determine the population levels required to adversely affect maize. Initial nematode population levels (Pi) evaluated were 0.0, 0.4, 4.0, or 42 nematodes/cm of soil (respectively, 0, 500, 5 000, or 50 000/pot). An additional treatment evaluated the effect of nematode associated microorganisms (AM) which accompanied the highest level of nematode inoculum. After 60 days, plant height, fresh and dry foliar and root weights and numbers of nematodes were determined. In both experiments plant height, fresh and dry foliar weight, root weight, and total plant weight were reduced significantly (P 0.05) by T. zambiensis at the highest inoculum level. In both experiments when Pi = 500 or 5 000 nematodes, effects of T. zambiensis on maize growth were inconsistent. Although roots appeared healthy, the AM treatment had a significant negative ef
