PS 40-19 - CANCELLED - An integrated approach to invasive tree management and edible mushroom cultivation

Background/Question/Methods

Invasive trees can dominate forest ecosystems, decreasing biodiversity and disrupting a wide variety of ecological functions. Management efforts are often expensive and labor-intensive, and linked to problematic or unknown effects on non-target organisms. The project described here focuses on an exciting new possibility for invasive tree control: intentional inoculation with cultivated edible mushroom strains to induce tree death while simultaneously producing a harvestable crop. We hypothesize that girdled inoculated trees, as compared to girdled trees with sterile plugs used as a procedural control, will have lower rates of canopy and root system survival, and that harvestable mushroom crops will emerge from all inoculated trees. To test the viability of this approach, we girdled 47 invasive Ailanthus altissima trees in a single large patch in central Virginia, United States, in August 2021. Shortly after, a random subset of these trees were inoculated with oyster mushroom spawn (golden: Pleurotus citrinopileatus, or grey dove: Pleurotus ostreatus), either above the girdle or above and below the girdle. Canopy condition and basal sprouting were observed in late October, just prior to autumn leaf drop, and monitoring will continue through the coming year.

Results/Conclusions

Girdled trees dropped their leaves earlier than nearby untouched trees, but there were no obvious differences between inoculated and uninoculated trees, nor were there any apparent differences related to fungal strain or inoculation position relative to the girdle (above only or above and below). Basal sprouts were minimal (only 6 trees had sprouts), and not related to inoculation status. Since tree death and mushroom production usually take at least six months, these results are preliminary, and all trees will be monitored throughout the spring and summer of 2022. While edible mushrooms are usually not sufficiently pathogenic to colonize living trees, previous research suggests that girdling trees before inoculation weakens them enough for mycelial colonization, enabling mushroom production on living (but dying) trees. This likely works because defensive compounds, which are usually synthesized on demand, have a high carbon cost. Currently unexplored is whether the probability and/or pace of tree death is greater when girdled trees are inoculated with fungi, edible or otherwise, but this should be the case given that the fungi operate as an additional stressor. Inoculation with edible mushroom mycelium may be an eco-friendly, cost-effective method of simultaneously producing edible mushrooms and controlling invasive trees.