Muscodor albus, a potential biocontrol agent against plant-parasitic nematodes of economically important vegetable crops in Washington State, USA

The fungus, Muscodor albus, was tested for nematicidal and nematostatic potential against four plant-parasitic nematode species with three different feeding modes on economically important vegetable crops in the Pacific Northwest. Meloidogyne chitwoodi, Meloidogyne hapla, Paratrichodorus allius, and Pratylenchus penetrans were exposed for 72 h to volatiles generated by M. albus cultured on rye grain in sealed chambers at 24 °C in the laboratory. In addition, the nematodes were inoculated into soil fumigated with M. albus, and incubated for 7 days prior to the introduction of host plants under greenhouse conditions. The mean percent mortality of nematodes exposed to M. albus in the chamber was 82.7% for P. allius, 82.1% for P. penetrans, and 95% for M. chitwoodi; mortality in the nontreated controls was 5.8%, 7%, and 3.9%, respectively. Only 21.6% of M. hapla juveniles died in comparison to 8.9% in controls. However, 69.5% of the treated juveniles displayed reduced motility and lower response to physical stimulus by probing, in comparison to the control juveniles. This is evidence of nematostasis due to M. albus exposure. The greenhouse study showed that M. albus caused significant reduction to all nematode species in host roots and in rhizosphere soil. The percent mortality caused by M. albus applied at 0.5% and 1.0% w/w in comparison to the controls was as follows: 91% and 100% for P. allius in the soil; 100% for P. penetrans in bean roots and soil; 85% and 95% for M. chitwoodi in potato roots, and 56% and 100% in the soil; 100% for M. hapla both in pepper roots and soil. In this study, M. albus has shown both nematostatic and nematicidal properties.