Activity of fungal culture filtrates against soybean cyst nematode and root-knot nematode egg hatch and juvenile motility

Fungi were isolated from soybean cyst nematode (SCN, Heterodera glycines) eggs collected in China, and 253 fungal isolates were assayed for production of compounds active against SCN and root-knot nematode (RKN, Meloidogyne incognita). Fungal isolates were grown for 3 and 7 days in potato dextrose broth (PDB), the culture broths were sterile-filtered to remove fungal biomass, and the filtrates were placed into 24-well plates to test for effects on egg hatch and juvenile motility. Meloidogyne incognita egg hatch ranged from 2 to 121% of hatch in PDB controls and H. glycines hatch from 15 to 224%. Activities of filtrates harvested after 3 and 7 days were significantly correlated. Only four isolates produced filtrates that significantly inhibited juvenile motility of SCN, RKN or both nematodes. This study identified fungal isolates capable of producing compounds active against these nematodes, and demonstrated that there was a low correlation in activity against SCN and RKN. The active fungal isolates are candidates for studies on identification of potential nematicides.