Oyster Mushroom Field Day
MUNICIPAL YARD TRIMMINGS AS SUBSTRATE-BASE FOR THE
COMMERCIAL PRODUCTION OF OYSTER MUSHROOMS
(Pleurotus ostreatus, P. pulmonarius, Pleurotus spp.)
November 1998 to December 2001
Investigators: María de la Fuente, Principal Investigator, Farm Advisor and County Director, and
Rosa María Gordillo, Research Associate, UCCE Santa Clara County.
Location: UC BAREC (Bay Area Research and Extension Center)
90 N. Winchester Blvd.
Santa Clara, CA 95050
Sponsors: City of San Jose Environmental Services Department, through its program San Jose in
Partnership with Agriculture (Michele Young)
Amycel – Spawn Mate, Inc. (Lupe Bañuelos)
BFI Organics Division (Hilary Gans, Gil Cheso and Jose Dueñas)
Automatic Rain Company (Jorge García)
UC BAREC (Zak Mousli)
A) Economic Importance.
Total mushroom production worldwide has increased more than 18-fold in the last 35 years from about
350,000 Ton in 1965 to about 5,810,000 Ton in 1999. The bulk of this increase happened during the last 15
years. A considerable shift has occurred in the composite of genera that constitute the mushroom supply.
During the 1979 production year, the button mushroom Agaricus bisporus accounted for over 70% of the
world's supply. By 1999, only 30% of the world production was A. bisporus. In 1998 to 99, the United
States produced about 900 million pounds of mushrooms. Agaricus bisporus accounted for over 80% of
total mushroom production value while Pleurotus spp. (Oyster mushroom) and Lentinula edodes (Shiitake)
were among the main specialty genera cultivated. For the past 10 years, specialty mushroom production
has increased an average of 30%. Based on recent and historical trends, it is expected that diversification
of the mushroom industry will continue in the country. The development of improved technology to cultivate
each species more efficiently, will allow consumer prices to decline and therefore demand to increase. The
culinary (and some times medicinal) advantages offered by specialty mushrooms bode well for the
continued growth and development of the specialty mushroom industry worldwide.
Assembly Bill 939 of the Integrated Waste Management Act required a 25% diversion of the state’s waste
from landfills by 1995, and a 50% diversion by 2000. The city of San Jose not only wants to be in
compliance with the Act, but additionally wants to find a new approach for the management of California’s
waste stream and perhaps have an impact on local agriculture.
Organic food and fiber are gaining popularity in both the United States and abroad. It is a $ 1 billion industry
that spans from the farmer’s market to major manufacturers of foods such as baby foods and tomato
sauces. The certified organic acreage in California has grown from 5,000 acres in 1986 to more than
50,000 acres by 1996. There are over 700 California organic farmers and organic food handlers.
Santa Clara County's agricultural main commodity is button mushrooms, the best-known type of cultivated
edible fungi. They represent annual average revenue for the County of $35-38 million dollars.
Santa Clara County agriculture is mainly composed of small farm ethnic growers that rely in methods other
than conventional for crop management, and could easily make the transition into organic agriculture,
provided they are properly trained and learn the criteria to be certified.
B) Biological or Environmental Importance.
The nutritional value of Pleurotus is comparable to mushroom and other edible fungi, and in some aspects
higher than other food products. Oyster mushroom life cycle can be completed in 12 to 15 days. This
means a potential production of 20 to 30 cycles a year.
The primary ingredients used for Pleurotus spp. commercial production is chopped wheat straw or
cottonseed hulls or mixture thereof. The substrate formula is spawned and filled into clear or black
perforated polyethylene bags, jars, plastic boxes or other containers, and then incubated for 12 to 14 days.
Since Pleurotus is a wood decomposing, saprophytic or parasitic fungus, in nature it grows abundantly on
standing and fallen alder, cottonwood and maple. Being a primary decomposer also grows on a wide
variety of cellulosic wastes. This species efficiently utilizes its substrate. Its ability to fruit on a single
component substrate, to permeate the straw rapidly while tolerating high carbon dioxide levels and to
produce abundant crops within a short time period, makes it ideal for home or low scale cultivation
C) Geographical Perspective
Santa Clara County is one of the most ethnically diverse areas in the nation. According to the 1990 Census,
the County population is: non-Hispanic Whites (58.1%), non- Hispanic Blacks (3.5%), Asian / Pacific
Islander (16.8%) and Hispanic Origin (21%) groups. Within the Asian / Pacific islander group, Chinese and
Japanese make up the highest percentage; most of these people are already culturally aware of the oyster
mushroom and they use it in their cuisine. This is giving the area a potential direct market, plus the
opportunities for exportation.
a) Development of alternative uses for municipal yard trimmings and grass clippings.
b) Environmentally controlled evaluation of the efficacy of three substrate formulas for commercial
production of oyster mushroom.
c) Evaluation of variety response to production methods of oyster mushroom for commercial purposes.
d) Provide an alternative of specialty crop for the area; an opportunity for produce diversification for the
growers, the existing markets, gourmet stores, and other consumers.
e) Study the consumer awareness and preference for a relatively new food product, oyster mushroom.
f) Study the marketing potential for oyster mushroom at a local, state, national and international level.
A) Development of Mushroom House
A shed (about 15’ x 17’) was modified to achieve semi-controlled conditions for oyster mushroom growing at
BAREC. See diagram. External walls and ceiling were insulated with insulation boards, Tuff-R Blackore ®,
an insulating sheathing made by Celofex ®, consistent of semi-rigid carbon black-filled polyisocyanurate-
foam with aluminum foil faces on both sides of about ¾ inch thickness. This gives an insulation coefficient
Wooden floors were twice treated with waterproof varnish.
Easy assembly 18” depth, 36” long by 18” wide plastic shelves, made into 4, 5 or 6 tiers (58”, 72”, or 86”)
height according to slopped ceiling (6’10” to 10’ height), were distributed to accommodate maximum
capacity and permit air flow and laborer movement in the shed. Shelf system is heavy-duty made of high-
impact plastic resin, for indoor and outdoor use, that will not rust, stain, peel or bend, and that with equally
distributed weight can hold up to 750 pounds per 5 assembled shelves. The shelves are vented, thus
preventing mold and mildew development, and feet raise shelf off floor, allowing dripping of water excess,
airflow and cleaning undersurface.
Total Height 82”
Height to ceiling
in the front
Working Height 70”
Height to ceiling
In the back
Temperature of substrate was measured and monitored with 4 pocket thermometers, all metal with a 1-inch
dial for spot-checking bags, and a 5-inch stem. Air temperature and relative humidity in the shed was
monitored with a battery operated LCD digital thermometer/hygrometer (Thermo-Hygro ®), which also
shows temperature maximums and minimums. Relative Humidity was adjusted through a time-set semi-
automated misting system (Raindial – Irritrol Systems ® Model RD 600 Ext). The pipes were distributed
along the production areas on the ceiling, with Turbo-Flo ® Misters, which are extremely low flow (1/2 gph)
with a very small droplet size. They work excellently as misting/humidifying and indoor cooling devices.
The misters were hookup to PVC pipes connected to an automatic anti-siphon valve and a Y-Filter
applicator. The system was connected to a brass gate valve used as a main system shutoff and to the
Irritrol System, a rain-dial series electronic controller, with an advanced design hybrid controller for water
applications. The station can be set to run times 1-59 minutes or 1-5.9 hours. The system also has a 4-E
Spin Clean Series Filter (API ®) which design forces incoming water through a directional nozzle plate. This
creates a high velocity, centrifugal action that force debris to rotate down the stainless steel screen and to
the holding basin at the bottom of the filter.
The experimental units consisted of autoclavable translucent bags with microporous filter patch that allows
gas exchange but prevents the passage of contaminant spores. The bags’ dimensions are 21 x 8 x 4 ¾
inches and because they are heat tolerant were ideal for sterilization of substrate material before spawning.
They can hold up to 25 pounds of material.
B) Experimental Design.
Three substrate formulas based on compost from city yard trimmings and grass clippings recollections, with
or without additional supplements; at least two production techniques with two or three commercial oyster
mushroom varieties (or strains); with multiple (more than 30 experimental units) replicates, in a bi-factorial
random plots statistical design.
Substrate Formulas: BFI - Yard Trimming Fine Compost (YTFC) (’99)
BFI - YTFC + Amycel Spawn Mate ® (’99)
BFI – Composted “Woodovers” + YTFC (3:1) (’00)
Production Techniques: Commercial Pasteurization (’99 & ’00)
Solarization (’99 & ‘00)
Commercial Varieties: Pleurotus pulmonarius Amycel 3014 ® (’99)
Pleurotus ostreatus Amycel 3015 ® (’99 & ‘00)
The project received in-kind donations of substrate ingredients from commercial composter (BFI Organics
®); the supplement and spawns from commercial spawn business (Amycel – Spawn Mate, Inc. ®), the
automated misting system from Automatic Rain Company, and the pasteurization treatment of the bags from
Royal Oaks Mushrooms in Morgan Hill.
D) Data Collection.
Flush intervals, number of breaks or flushes, yield per flush, size and weight of fruiting bodies, color, grade,
yield per experimental unit, total yield and biological efficiency.
E) Methods of evaluation used in reaching objectives.
Statistical analysis (ANOVA) to prove differences between the substrate formulas, production techniques
and production times, as well as the varietal response, to the several data to be collected. Field Days at
BAREC with growers and industry, with tasting sampling of some dishes made with oyster mushroom,
opportunities for consumer evaluation, and display of nutritional information.
Product samples, pictures of production systems, nutritional value, and other pertinent information has been
displayed in posters at public festivals or fairs (sampling and tasting) and other similar opportunities for
The three-substrate formulas used in 1999 had different rates of success after spawning. One reason might
have been that we used the lowest recommended commercial rate for spawning, 2%. We did have limited
amount of spawn.
We started with 75 pasteurized bags and only 74 were in production, therefore a 99% of efficiency. We also
had 75 pasteurized bags supplemented with Spawn Mate ®, but only 62 were in production, therefore 83%
efficiency. We started with only 50 solarized bags, and only 39 achieved production status, therefore 78%
Every experimental unit had 5 pounds (2,268 g) of dry matter and were adjusted to 75% moisture content
before and after pasteurization and solarization. It is estimated that during both processes the compost lost
2-3% moisture content, therefore the second adjustment. Final weight of bags was 10.5 lbs. (4,763 g).
They were randomly distributed in the shelves and substrate and air temperature monitored during spawn
running. Average spawn-running time, varied with the substrate. For pasteurized bags was 50 days
average, for pasteurized bags with supplement was 55 days and with solarized bags 75 days. See table 1
and figure 2.
The summarized results of the yields of Pleurotus pulmonarius grown on Yard Trimming Compost, are
shown in table 1 below, and graphic comparison of the yields are shown in figure 1.
Table 1. Summarized Results Yield of Pleurotus pulmonarius grown on Yard Trimming Compost - 1999
Yield / Flush (g) TOTAL Average Yield / Bag (g) xTOTAL
Exp. Units Flush 1 Flush 2 Flush 3 Flush 1 Flush 2 Flush 3
Pasteurized (X) 75 (74) 14651 7339 3851 25841 198 116 66 380
1999 Pasteurized plus SPM 75 (62) 10645 5787 2901 19333 172 98 59 329
Solarized (NA) 50 (39) 5338 2664 1570 9572 137 81 63 281
Pasteurized (X) 50 80 100 25
production Pasteurized plus SPM 55 90 100 22
Solarized (NA) 75 85 120 22
For the year 1999 we are presenting the results of three flushes. Production could have been extended to
two or three flushes more, but we couldn’t gather results, so we stopped it. As shown in table 1 and in figure
2, the average days between flushes varies wit the substrate. There are 30 days difference between first
and second flush for the pasteurized bags, and 20 days difference between the second and third. There are
35 days difference between first and second flush for pasteurized bags plus supplement, and only 10 days
(more like commercial results) between the second and third flush. For the solarized bags, there is only 10
days between the first and second flush (also more like a commercial production), but 35 days between the
second and third one (see figure 2).
Average Yield of P. pulmonarius grown on
Yard Trimming Compost (1999)
150 pasteurized plus
1 2 3
For the year 2000 we are presenting the results of three flushes. Production still occurring and we are
expecting at least two or three flushes more. As shown in table 2 and in figure 4, the average days between
flushes varies with the substrate. There are only 13 days difference between first and second flush for the
pasteurized bags, but 34 days difference between the second and third. For the solarized bags, there is
only 15 days between the first and second flush (also more like a commercial production), but 5 days
between the second and third one (see figure 4).
The two-substrate formulas used in 2000 had also different rates of success after spawning. This year we
used a higher spawning rate, 3% but still we had limited spawn material.
We started with 75 pasteurized bags and only 72 are in production, therefore a 96% of efficiency. We
started with only 45 solarized bags, and only 43 achieved production status, therefore same 96% efficiency.
Although better than last year, we still can improve it if we increase the spawning rate to a more commercial
level 4 to 5% (w/w fresh weight).
Number of days to production for P.pulmonarius
grown on Yard Trimming Compost (1999)
60 plus SPM
40 Solarized (NA)
0 2 4
This year, due to the different consistency and texture of the substrate, every experimental unit had 6
pounds (2,722 g) of dry matter and were adjusted to 80% moisture content before and after pasteurization
and solarization. It is estimated that during both processes the compost lost 2-3% moisture content,
therefore the second adjustment. Final weight of bags was 12 lbs. (5,443 g). They are also randomly
distributed in the shelves and substrate and air temperature monitored during spawn running. Average
spawn-running time, varied with the substrate. For pasteurized bags was 48 days average, a 4 %
improvement from previous year; and for solarized bags 60 days, a 20% improvement from previous year.
See table 2 and figure 4.
The summarized results of the yields of Pleurotus pulmonarius grown on Composted “Woodovers”, are
shown in table 2 below, and graphic comparison of the yields are shown in figure 3.
Table 2. Summarized Results Yield of Pleurotus pulmonarius grown on Composted "Woodovers" - 2000
Yield / Flush(g) TOTAL Average Yield / Bag (g) xTOTAL
Treatment Exp. Units Flush 1 Flush 2 Flush 3 Flush 1 Flush 2 Flush 3
2000 Pasteurized 75 (72) 5520 4301 2412 12233 77 67 52 196
Solarized 45 (43) 5019 1711 478 7208 114 63 48 225
Pasteurized 48 61 85 18
Solarized 60 75 80 10
Table 3 shows a summary of all data collected in the five different substrate treatments. Biological
Efficiency is far below expected. We still need to deal with the heterogeneity of the substrate, and find out
optimum inoculation (spawning) rate to achieve maximum potential production of the substrates
Average Yield of P. pulmonarius grown on
Composted Woodovers - 2000
1 2 3
Number of days to production of P. pulmonarius
grown on Composted Woodovers - 2000
0 1 2 3 4
Table 3. Summarized up-to-date Data Collection for the different treatments Year 1999 and 2000
S u b s t r a t e T r e a t m e n t s
Data Collection YTC+Past YTC+SPM+Past YTC+Solar Woodover+Past Woodover+Solar
Experimental 74 62 39 72 43
Units (bags) EU
% Efficiency 99 83 78 96 96
Number Flushes 3 3 3 3+ 3+
Average days of 25 25 22 18 10
Average g Yield 127 110 94 65 + 75 +
per Flush per EU
Average g Total 349.21 311.82 245.44 169.90 + 167.63 +
Yield per EU
Biological 15.4 13.7 10.8 10.0 + 7.0 +