Commercial Production of Tropical Mushrooms Grown Organically
The island of Guam is populated by a variety of people from the Pacific Islands, from various parts of Asia, and from U.S.A. Both Asian and U.S. American people are fond of mushrooms. The population in general is getting accustomed to more and more varied foods and becoming more aware of foods that are good for you. At the University of Guam, we have already identified several tropical mushroom species that grow well under our tropical conditions. At present, the local demand for mushrooms is being met by the import of temperate species, mostly Agaricus sp., which is brought in fresh from the U. S. mainland, and by canned straw mushrooms, brought from Asia. Local restaurants have expressed a keen interest in the availability of fresh, locally grown mushrooms. We set out to develop and test a way of growing organic tropical mushrooms commercially.
1. To develop and test a pilot method for commercial production of organically grown tropical mushrooms.
2. To offer open-house demonstrations and workshops in order to convey the available information to students, extensionists, and potential producers.
This year we tried to recuperate from the ravages of two typhoon storms that hit us late last year. We lost our 40-foot container where we had installed a lab and a growing room. We also lost our research assistant, who almost died in the last storm and left the island as a consequence.
We managed to hire a replacement, although he had to be trained. We salvaged the damaged container and made the necessary repairs. The floor had to be changed. A lot of materials and lab instruments were lost. We made a steam generator from a 55-gallon drum fitted with galvanized pipes and sitting on a large outdoor-type burner. We managed to rescue the 100-lb LP gas bottle and were able to use it for this purpose.
Regarding the cultivation of straw mushroom (Volvariella volvacea) indoors, we had many problems. The temperatures in the container’s growth room were running too hot on a daily basis, so we tried to mitigate the situation with insulation and with sprinkler irrigation on the top, or both, to no avail. Daily average temperatures inside the container growth room were still too high for V. volvacea, the straw mushroom, which failed to fruit.
Outdoor production of the straw mushroom, V. volvacea is relatively simple procedure requiring no special equipment, provided spawn is available. Although it is a somewhat inefficient way of producing mushrooms, the biggest obstacle encountered with this simple method is the availability of raw material. We have used dry banana leaves successfully, but availability is limited. The major banana producer on island sprays fungicides on his banana plantation regularly to control foliar diseases, making his dried leaves undesirable for mushroom production. Grass straw is another alternative substrate, but is not readily available either. Newspaper was also used with some success, but shredding it is extremely labor-intensive.
Outdoor methods of growing other mushroom species were worked out. We had a collaborator interested in producing the medicinal Ganoderma lucidum. This species is quite hardy and has grown quite well. We have produced great volumes of it, and it keeps well for months at a time. It is used for making a medicinal tea out of ground fruiting bodies, which are rather woody and dry. However, this fact makes them weigh very little, and there is concern from the collaborator as to his profit margin.
The tropical oyster mushroom, Pleurotus ostreatus sajor-caju, is a reliable producer, but its culture requires either a trained person to inoculate the bagged and sterilized substrate or a source of inoculated bags ready to grow. Once inoculated, these substrate bags need an indoor space to grow for about a month. To sterilize and inoculate these bags, an autoclave and a laminar flow hood are needed, plus training is required on the proper handling of pure cultures. This has become the main obstacle in the production of this species. Still, this is the most viable option that we have found for Guam, and we are planning to recommend this species. A detailed instruction manual has to be written, and an open house will be organized to present this method to interested persons.