Survival of Four Ganoderma Species and Several Wood-inhabiting Fungi in Different Soil Matrix Potentials

Abstract

The survival of Ganoderma australe, G. boninense, G. lucidum and G. weberianum mycelia, and of Ganoderma-colonized wood was measured in soils with different soil matrix potentials. G. australe and G. boninense producd no chlamydospores, while G. lucidum and G. weberianum did. Mycelia of G. australe and G. boninense buried in the -0.025 MPa soil moisture treatment declined rapidly and could not be recovered at 9 and 12 wk, respectively. Mycelia buried in the -0.50 MPa soil moisture treatment had relatively higher recovery rates at the same incubation times compared with those in the higher soil moisture treatments. However, mycelia were not recovered at 15 wk in any treatment. Survival of G. lucidum and G. weberianum mycelia in all soil moisture treatments rapidly declined from 0 to 15 wk after incubation. However, survival of mycelia consistently ranged from 35• to 50• at 15 to 52 wk after incubation. These results indicate that chlamydospores in soil play an important role in the long-term survival of Ganoderma species when mycelia are not harbored in woody debris. G. australe and G. boninense were not recovered from pieces of artificially infested wood subjected to 1 and 3 mo of flooding, respectively. In treatments with the lower soil moisture, the survival of these 2 fungi ranged from 80• to 90• over 2 yr. In all soil moisture treatments, G. lucidum and G. weberianum ranged from 80• to more than 90• over 2 yr. These results indicate that, regardless of chlamydospore formation, woody debris in soils harboring Ganoderma species plays an important role in the long-term survival of the fungi, and chlamydospores of Ganoderma in woody debris enhance the resistance of the fungi to environmental stress such as flooding. Seven species of other wood-inhabiting fungi which do not produce chlamydospores were not recovered from pieces of artificially infested wood subjected to 1 or 5 mo of flooding. In a treatment with a lower soil moisture (-0.50 MPa), the survival of these 7 fungi ranged from 70• to more than 90• over 2 yr. However, the survival of others that produced chlamydospores ranged from 70• to more than 90• in soils with -0.50 MPa and flooding. These results are similar to those for Ganoderma species and indicate that chlamydospores of wood-inhabiting fungi and woody debris play an important role in their long-term survival and in their resistance to environmental stresses such as flooding. Flooding infested fields may help control wood-inhabiting fungi which do not produce chlamydospores, but may have little effect on those which produce chlamydospores in the field.