Plant-parasitic nematodes cause significant economic losses to a wide variety of crops. Chemical control is a widely used option for plantparasitic nematode management. However, chemical nematicides are now being reappraised in respect of environmental hazard, high costs, limited availability in many developing countries or their diminished effectiveness following repeated applications. This review presents 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 commercialisation of these microorganisms lags far behind their resource investigation. One limiting factor is their inconsistent performance in the field. No matter how well suited a nematode antagonist is to a target nematode in a laboratory test, rational management decision can be made only by analysing the interactions naturally occurring among ''host plant-nematode target-soil-microbial control agent (MCA)-environment''. As we begin to develop a better understanding of the complex interactions, microbial control of nematodes will be more fine-tuned. Multidisciplinary collaboration and integration of biological control with other control methods will also contribute to more successful control practices.

A new taxon with Dyrithium-like characteristics was collected from Lake Fuxian in China. The taxon is typical of the Amphisphaeriaceaein that it has relatively large, ostiolate, immersed ascomata, unitunicate asci with a J + subapical ring, and brown ascospores. It is similar to Dym'thium in that it has muriform ascospores, but considerable confusion surrounds this genus. In Dyrithium asci are bitunicate and lack a J + subapical ring, while this was not true of our species. A new genus, Dyrithiopsis, therefore is established to accommodate this new taxon. Details of its anamorph also are provided, based on cultural studies. Parsimony analyses of part of the large-subunit rDNA provide further evidence to support the familial placement of this new genus in the Amphisphaeriaceae. The taxonomic position of Dyrithium also is discussed.

A new taxon with Dyrithium-like characteristics was collected from Lake Fuxian in China. The taxon is typical of the Amphisphaeriaceaein that it has relatively large, ostiolate, immersed ascomata, unitunicate asci with a J + subapical ring, and brown ascospores. It is similar to Dym'thium in that it has muriform ascospores, but considerable confusion surrounds this genus. In Dyrithium asci are bitunicate and lack a J + subapical ring, while this was not true of our species. A new genus, Dyrithiopsis, therefore is established to accommodate this new taxon. Details of its anamorph also are provided, based on cultural studies. Parsimony analyses of part of the large-subunit rDNA provide further evidence to support the familial placement of this new genus in the Amphisphaeriaceae. The taxonomic position of Dyrithium also is discussed.

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