Introduction; Background and previous work; Research objectives; Effect of organic amendment placement and inoculum density of meloidogyne incognita on okra seedlings; Introduction; Materials and methods; Results and discussion; Effect of planting date and inoculum density of meloidogyne incognita on okra; Introduction; Materials and methods; Results and discussion; Effect of mulch, irrigation frequency, and inoculum level of meloidogyne incognita on 'clemson spineless' okra; Introduction; Materials and methods; Results and discussion; Effect of fresh and dry organic amendments on meloidogyne arenaria in greenhouse experiments; Introduction; materials and methods; Experiment 1 (Winter 1995); Experiment 2 (Summer 1995); Results and discussion; Experiment 1; Experiment 2; Effect of castor and velvetbean organic amendments on meloidogyne arenaria in greenhouse experiments; Introduction; materials and methods; Experiment 1 ( Velvetbean amendment); Experiment 2 (Castor amendment); Experiment 3 ( Combined amendments, velvetbean and castor); Results and discussion; Experiment 1 ( Velvetbean amendment); Experiment 2 ( Castor amendment); Experiment 3 (Combined amendments, velvetbean and castor); Effect of nematode level (Meloidogyne arenaria race 1 ) and mulch type on ' clemson spineless' okra in a microplot experiment; Introduction; Materials and methods; First year - 1994; Second year -1995; Third year -1996; Results; Okra plant growth; Amendment effect;Nematodes; Rye cover crop; Soil properties and nutrients; Plant nutrients; Discussion; Conclusions; References; Biographical sketch.Thesis (Doctor odf Philosophy) - University of Florida, Gainesville. Orientation: Robert McSorley.