King Oyster Mushroom - Pleurotus eryngii

Scientific Name: Pleurotus eryngii
Common Name: King oyster mushroom

King oyster mushroom

Pleurotus eryngii is by far the best tasting Oyster mushroom, well deserving of the title, the King Oyster. Popular in Europe, this stout, thickly fleshed mushroom, is one of the largest species in the genus. Preferring hardwoods, this mushroom is easy to grow. Although this mushroom grows on cereal (wheat) straws, the yields are not as substantial as that of Pleurotus ostreatus and Pleurotus pulmonarius on this same material, at the same rate of spawning, unless supplements are added or a unique spawning method is employed.

Mycelial Characteristics: Whitish, longitudinally radial at first, sometimes rhizomorphic, soon thickening and becoming cottony in age.

Microscopic Features: This mushroom produces white spores.

Suggested Agar Culture Media: Malt Yeast Peptone Agar (MYPA) or Potato Dextrose Yeast Agar (PDYA).

Spawn Media: Rye, wheat, sorghum, milo, or millet.

Substrates for Fruiting: Most hardwoods, wheat straw, and cottonseed hulls or wheat bran support fruitings. Currently most grow this on hardwood fuel pellets with 10-20 % Wheat Bran. This mushroom is not as adaptive as P. pulmonarius and P. ostreatus to a broad range of substrates. Nevertheless, many materials can be used. It seems to perform well on recycled, re-sterilized waste Shiitake substrate. However, it is not recommended for commercial purposes unless the preferred wood type or alternative substrate materials were exceedingly scarce or cost-prohibitive. If cultivation this mushroom on wheat straw, the addition of 5-10% cottonseed meal reportedly has the greatest effect in enhancing yield.

Yield Potentials: 1 lb. or mushrooms per 5 lbs. of sterilized sawdust/chips/bran. Wheat straw fruitings, in some experiences, have tallied approximately 1/2 of that from enriched sawdust. The stage at which the mushrooms are picked significantly affects yield efficiencies.

---Growth Parameters---

Spawn Run:

Incubation Temperature: 75* F (24* C)
Relative Humidity: 90-95%
Duration: 12-16 days
CO2: 5000-20,000 ppm
Fresh Air Exchanges: 1 per hour
Light Requirements: n/a
Primordia Formation:

Initiation Temperature: 50-60* F (10-15* C)
Relative Humidity: 95-100%
Duration: 4-5 days ( allow to pin in the bag before opening)
CO2: 500-1000 ppm
Fresh Air Exchanges: 4-8 per hour
Light Requirements: 500-1000 lux
Fruitbody Development:

Temperature: 60-70* F (15-21* C)
Relative Humidity: 85-90%
Duration: 4-8 days
CO2: <2000 ppm ( Co2 concenteration will greatly affect shape of the mushroom. 2-4 exchanges per day will give fat long stems while higher FAE will give short stems with larger caps)
Fresh Air Exchanges: 4-5 per hour (see above)
Light Requirements: 500-1000 lux
Cropping Cycle:

45 days, two crops, 14 days apart
Comments: The King Oyster's stout form, short gills, and thick flesh, coupled with its pleasing flavor strongly commends this species amongst connoisseur growers and chefs. The short gills mean this mushroom releases comparatively fewer spores per lb. of harvested mushrooms. a significant advantage over the other Oyster species. Gary Lincoff reported that this mushroom received the highest acclamations of any of the mushrooms tasted during a culinary tour of mycophagists sampling the treasured mushrooms of Europe. It seems that this is the only Oyster that ships well over long distances and has an extended shelf life.

Although a casing layer has been recommended by other cultivators, some have found its application to be unnecessary. For great fruitings of Pleurotus eryngii, both in terms of yields and quality, some use, 20% bran-enriched alder sawdust. Three weeks after inoculation with grain spawn, the fully colonized bags of sterilized sawdust/chips/bran are brought into the growing room. The top of the bags are horizontally sliced open, resulting in a 3-4 inch plastic wall around and above the surface plane of the mycelium. In effect, these side walls protect the supersensitive aerial mycelium from sudden dehydration. Condensation is promoted. Coupled with a descending fog environment within the growing room, the perfect micro climate for primordia formation is provided.

Zadrazil showed mycelial growth peaked when carbon dioxide levels approached 220,000 ppm or 22%. The stimulatory effect of CO2 on mycelial growth allows this mushroom to grow under conditions which would be stifling for most other mushrooms and lifeforms. Optimum pH levels at the time of spawning should be between 7.5-8.5. On wheat straw, the pH naturally declines to a range of 5.5-6.5, a range ideal for fruiting.

(Information taken from Growing Gourmet and Medicinal Mushrooms, Paul Stamets)