RELATION SOIL AMENDMENTS AND MICROBIAL ANTAGONISTS FOR BIOLOGICAL CONTROL OF NEMATODES

Plant-parasitic nematodes are important factors affecting crop growth and yield in all agricultural production zones. However, chemical nematicides are now being reappraised in respect of environmental hazards, high costs, limited availability in many developing countries or their diminished effectiveness following repeated applications.  This review presents the progress made in the field of microbial antagonists of plant-parasitic nematodes, including nematophagous fungi, endophytic fungi, actinomycetes, and bacteria. A wide variety of microorganisms are capable of repelling, inhibiting or killing plant-parasitic nematodes, but the commercialization of these microorganisms lags far behind their resource investigation. One limiting factor is its inconsistent performance in the field. No matter how well suited a nematode antagonist is to a target nematode in a laboratory test, rational management decisions can be made only by analyzing the interactions naturally occurring among "host plant nematode target soil microbial control agent (MCA) environment". Organic soil amendments stimulate the activities of microorganisms that are antagonistic to plant-parasitic nematodes. The decomposition of organic matter results in accumulation in the soils of special compounds that may be nematicidal. Amendments are mainly bioproducts and wastes from industrial, agricultural, biological and other activities. Control of plant-parasitic nematodes can be by improvements of soil structure and fertility, alteration of the level of plant−resistance, the release of nematode toxic compounds), parasites (fungi and bacteria) and other nematodes antagonistic (biological control agents). The mode of action of organic amendments leading to plant disease control and stimulation of microorganisms is complex and dependent on the nature of the amendments. KEYWORDS: Biological control, Microbial control, Plant parasitic nematode