Do Organic Amendments Enhance the Nematode-Trapping Fungi Dactylellina haptotyla and Arthrobotrys oligospora?

Soil cages (polyvinyl chloride pipe with mesh-covered ends) were used to determine how the quantity of two organic amendments affected the nematode-trapping fungi Dactylellina haptotyla and Arthrobotrys oligospora, which were studied independently in two different vineyards. Each cage contained 80 cm(3) of field soil (120 g dry weight equivalent), fungal inoculum (two alginate pellets, each weighing 1.9 mg and containing assimilative hyphae of one fungus), and dried grape or alfalfa leaves (0, 360, or 720 mg equivalent to 0, 4,500, or 9,000 kg/ha) with a C:N of 28:1 and 8:1, respectively. Cages were buried in the vineyards, recovered after 25 to 39 days, and returned to the laboratory where fungus population density and trapping were quantified. Dactylellina haptotyla population density and trapping were most enhanced by the smaller quantity of alfalfa amendment and were not enhanced by the larger quantity of alfalfa amendment. Arthrobotrys oligospora population density was most enhanced by the larger quantity of alfalfa amendment, but A. oligospora trapped few or no nematodes, regardless of amendment. Trapping and population density were correlated for D. haptotyla but not for A. oligospora.