Nine Palms Ranch Trial, 2009

Lead: Jim Maley

Team members: Mike Kent, Bader Kudsi, Dan Johnston, with assistance from Joe Gallegos, Ian Gerbode and Keith Hubbard

Summary

This trial investigated implementing the bag method of mushroom cultivation under typical home garden conditions, using Blue Oyster mushroom spawn on a rice straw substrate. It was shown to be successful, with appropriate care taken.

Background

After a failed approach to growing oyster mushrooms in a 2008 Earth Box experiment, some formal training was required. A team member attended a January 2009 seminar conducted at Hidden Villa in Los Altos Hills and shared this training with other Master Gardener team members. This course featured a "bag culture" approach to the problem of growing oyster mushrooms. Test bags prepared at the Hidden Villa premises were quite successful in producing good mushroom yields using warm weather spawn called Blue Oyster (Pleurotus columbinus) and its expansion in a hydrated rice straw substrate. This experience has formed the basis of a multi-phase trial to be conducted at the Nine Palms Ranch research facility.

Hypotheses

Some hypotheses for the Phase 1 Trial are as follows:

1. The bag culture approach will work under the less than sterile conditions of an average home or garden.
2. The spring temperature range will support Blue Oyster mycelium expansion and mushroom fruiting.
3. The method of harvesting and storage will be viable for food preparation and a group tasting.

Method

The trial started with the purchase of the following materials:

• Blue Oyster mushroom warm weather grain spawn (6.5lbs)
• Pickling lime, 1 can
• Vacuum packaging bags, 1 roll
• Bag sealer (kitchen variety)
• Rice straw, 1 bale
• Galvanized garbage can, 35 gallons
• Candy thermometer
• pH meter (common garden-variety)
• Spray bottle

Also used were miscellaneous equipment/items at Nine Palms Ranch: machete, heavy twine, propane burner, and pitchfork. See Appendix A for a summary of steps conducted for Phase 1.

The first order of business was to cut the rice straw shafts into 3-4 inch segments using a machete and a slotted board has shown below:

Chopping straw

This approach, though tedious, was quite effective in achieving shorter shafts of straw, enhancing mycelium takeover.

It was decided, to complete two bag cultures first to verify method. In this case, a large kettle was used to pasteurize the rice straw in boiling water for 90 minutes maintaining temperature as close to 160°F as possible. Approximately 1/4 cup of pickling lime was added to the water to bring the pH of the mix to about 12. This high pH solution was prepared to minimize competition of various fungi contaminants. Freezer bags were then cut into approximate 18-inch lengths and the bottoms sealed. The straw was left to cool (approximate 80°F) and some of the moisture was squeezed out of it before bag stuffing. The bags were then stuffed alternatively with rice straw and handfuls of spawn. At this point, the exact ratio amounts of spawn to rice straw was not quantified. Experience gained in the Hidden Villa class was used to approximate the amounts needed. The bags were stuffed tight using "fist pressure" to ensure good contact between the spawn and the rice straw substrate. After the bags were stuffed, the ends were tied off with strong twine. The bags were then pierced by sharp knife making X-shaped, "breather holes", three per each quadrant. One such cut was made in the bottom of each bag to allow excess moisture to drain. These bags were then hung with twine as will be discussed later.

A week later, it was obvious after visual inspection that the first two tests bags exhibited mycelium expansion in the substrate. It was decided to complete the remaining bags in a larger scale effort. The chopped rice straw was then heated in a galvanized garbage can at the temperature range and time period noted above. Again, pickling lime was added to the mix and proportioned to bring the pH up to 10-12. The picture below shows this very important pasteurization effort.

Pasteurizing the straw

The straw was then laid out to cool and bags stuffed tightly as done previously. The process is shown below.

Stuffing bags

The completed bags were pierced as before and hung in a row in the Nine Palms Ranch gazebo in a diffused light situation. This arrangement is shown below.

Hanging bags

In the first two weeks or so, it was apparent that the mycelium again was expanding in the substrate. The first fruiting of mushrooms occurred between weeks three and four. Bags were checked periodically to ensure that mushroom fruiting bodies located the pre-established "x-cuts" in the bags. In most cases, fruiting bodies found the holes successfully. In a some, however, additional lancings were required. Additionally, during the latter stages of the fruiting process, a water spray bottle was used to mist mushroom caps that appeared to be drying. Periodic inspection was needed for this purpose.

A typical bag showing initial flush fruiting is shown in the following figure. Notice that some of the caps occur where there are no holes (near the bag bottom) and hence the need for occasional re-lancing of the bags.

Initial flush fruiting

A mushroom dish was prepared for all workers at the Nine Palms Ranch facility. An excellent dish for sampling oyster mushrooms is to eat them in battered fritters. A Turkish dish called Mantar Kizartmasi using a simple flour-based batter was prepared and accompanied by a savory dipping sauce from Greece called Skordalia. Recipes for these two dishes are included in Appendix B.

Results and Findings

In summary, a significant amount of Blue Oyster mushrooms were grown at the Nine Palms Ranch facility. The encouraging work of Phase 1 will form a basis for follow-up mushroom work in our Master Gardener program. Summaries of findings versus hypotheses are as follows:

1. Bag cultures will work in a non-sterile environment
   This was proven to be true and all bags produced fruiting bodies.
2. The spring temperature range will support Blue Oyster mycelium expansion and mushroom fruiting
   This was proven to be true even though actual temperatures fell outside the ideal temperature range for this mushroom variety which is 55°F to 75°F. All nights were cooler than the 55°F lower limit for this summer Blue Oyster mushroom culture. There were also some days where the temperature exceeded 75°F.
3. Method of harvesting and storage will be adequate for group serving
   This was only partially true as a number of mushroom caps were picked in a relatively dry state. They had to be rehydrated prior to use.

Lessons learned

One bag lagged all others in fruiting mushrooms. Team members could not explain this and possible reasons were given such as contaminants present or perhaps a lower ratio of mushroom spawn for the amount of substrate straw in the bag. This bag had to be rehydrated as the substrate was drying. It then fruited with about the same amount of mushrooms as the others. Quantification and adherence to specific proportions of spawn to straw substrate will allow better investigation during phase 2. Also the method of piercing the bags with a knife proved to be crude and haphazard. Some of the holes were larger than others and probably accounted for premature drying. In phase 2, a four bladed arrowhead will be used to produce all air holes in a uniform manner.

Timing of fruiting bags proved to be another issue. The team had to resort to harvesting some mushrooms fairly dry, then hydrating them before blanching and freezing. This proved satisfactory, but for culinary purposes, mushroom should be harvested, kept cold for a few days and then served. This particular Blue oyster variety had significant texture. They were tougher than the more common tree oyster mushroom, which is Pleurotus ostreatus. The Blue Oyster mushroom is best served fresh if possible.

Phase 2 ideas (to be developed further)

In phase 2, we hope to duplicate success using selected alternatives. In this phase, we are again going to grow Blue Oyster mushrooms, but quantifying results primarily using production weights as in other Nine Palms Ranch trials. In this phase, we will look at alternatives in substrate media such as rice straw versus wheat straw, amounts of spawn added, evaluating age/refrigerated spawn productivity, weighing bag culture productivity versus other container approaches like small laundry baskets etc.

In the next phase, we will capture spores from fresh fruiting bodies of the Blue Oyster mushroom. Researching this, the approach will rely on an identification approach used used successfully for wild mushroom ID. This involves creating spores patterns on clean glass squares hinged together. After the spore print, the hinged second piece of glass is sandwiched over the first and then secured with tape. The spores would then be captured in a sterile environment. These spores are now transportable to homes (possibly at Nine Palms Ranch) for Petri dish work. The idea is to grow our own spawn blocks starting with these spore print droppings. A laminar flow hood (donated to the trial) will be used for this purpose.

As part of phase 2, we are working on trying to cultivate corn mushrooms known as Cuitlacoche (Ustilago maydis) in an Earth Box off the Nine Palms Ranch campus to prevent contamination with other trial corn crops.

Phase 3 (details depend on Phase 2 results)

This phase will occur in wet time of the fall. We can choose different mushrooms to grow such as standard Tree Oyster mushrooms, Shiitake and others, using various approaches such as bags, logs and possibly sewing them in the winter gardens as companion crops.

Conclusion

The bag method of mushroom cultivation can be successfully implemented under typical home garden conditions, with appropriate care.

Appendix A

Blue Oyster Mushroom Trial - Step by Step Process

1. Prepare one-third bail of straw by cutting to 3- or 4-inch lengths.
2. Prepare large can of water adding straw at 180°F.
3. Estimate water volume and add pickling lime.
1. Proportion pickling lime to 1/2 cup for 10 gallons.
2. Check pH and ensure it is about 10+ to 12.
3. Sanitize a pitchfork in the hot water.
4. Pasteurize straw for 90 minutes maintaining temperature at 160°F.
5. Prepare 10 bags with sealed bottoms, each about 2 feet long.
6. Place pasteurized straw on a table for cooling.
1. Clean table or use clean tarp.
2. Use pitchfork to heap straw on the table.
3. Let straw cool on the table until about 80°F.
7. Pack bags.
1. Proportion spawn (about a half pound of spawn per bag).
2. Pack bags tightly with alternate layers of straw and 1/4-inch spawn between each layer.
8. Seal bags tightly on the top with twine.
9. Lance the bags appropriately using a sanitized instrument.
10. Hang the bag in the shaded, airy place.
11. Check bags for fruiting bodies.
1. Lance bags to release caps if necessary.
2. Mist fruiting bodies as necessary to prevent drying.
12. Harvest mushrooms and store for food preparation.

Appendix B

Kizartmasi Turkish Beer Batter Fritters

1 cup beer (strong near beer used)
3/4 cup flour
1/4 cup corn meal
1/8 tsp salt
1/8 black pepper
1 pound oyster mushrooms
2 tbsp onion powder
2 tbsp garlic powder

Whisk beer, flour, meal and spices into batter. Cut mushrooms into bite size pieces and stir into batter. Drop into hot vegetable oil. Fry until golden yellow then drain. Serve with Skordalia sauce.

Greek Skordalia Sauce

2 tbsp walnuts
3 tbsp French bread
6 tbsp mashed potatoes
2 tsp garlic to taste
1/2 cup red wine vinegar
1 tbsp salt
1 tbsp black pepper
1/2 cup olive oil
Juice of one lemon

Blenderize ingredients together into smooth sauce, adjusting seasoning or adding water as needed.