Hypsizygus tessulatus

A delicious species, H. tessulatus falls under the umbrella concept of the Japanese "Shimeji" mushrooms. Firm textured, this mushroom is considered one of the most "gourmet" of the Oyster-like mushrooms. Recently, this mushroom has been attributed to having anti-cancer properties. I ncreasingly better know, this obscure mushroom compares favorably to P. ostreatus and P.pulmonarius in North American, European and Japanese markets.

Mycelial Characteristics: Mycelium white, cottony, resembling P. ostreatus mycelium but not as aerial. Also, the mycelium of H. tessulatus does not exude the yellowish-orange metabolite nor does it form the classically thick, peelable mycelium, two features that are characteristic of Pleurotus species.

Mircroscopic Features: This mushroom produces white spores.

Suggested Agar Culture Media: Malt Yeast Peptone Agar (MYPA), Potato Dextrose Yeast Agar (PDYA), Dog Food Agar (DFA), or Oatmeal Yeast Agar (OMYA)

Spawn Media: The first two generations of spawn can be grain. The third generation can be sawdust or grain.

Substrates for Fruiting: Supplemented sawdust. Good wood types are cottonwood, willow, oak, alder, beech, or elm. The effectiveness of other woods has not yet been established. It seems that straw does not provide commercially viable crops unless inoculated up to 25% of its weight with sawdust spawn.

Yield Potentials: 1/2 lb. of fresh mushrooms per 5 lb. block (wet weight) of supplemented hardwood sawdust/chips.

---Growth Parameters---

Spawn Run:

• Incubation Temperature: 70-75* F (21-24* C)
• Relative Humidity: 95-100%
• Duration:30-45 days
• CO2: >5000 ppm
• Fresh Air Exchanges: 0-1 per hour.
• Light Requirements: n/a

Primordia Formation:

• Initiation Temperature: 50-60* F (10-15* C)
• Relative Humidity: 98-100%
• Duration: 7-12 days
• CO2: 500-1000 ppm
• Fresh Air Exchanges: 4-8 per hour
• Light Requirements: 500-600 lux

Fruitbody Development:

• Temperature: 55-65* F (13-18* C)
• Relative Humidity: (85) 90-95%
• Duration: 5-10 days
• CO2: 2000-4000 ppm
• Fresh Air Exchange: 2-4 per hour
• Light Requirements: 400-600 lux

Cropping Cylce:

• Two crops, three weeks apart.

Comments: A quality mushroom, Buna shimeji is popular in Japan and is being intensively cultivated in the Nagano Prefecture. The only two mushrooms which come close to this species in over-all quality are H. ulmarius or Pleurotus eryngii.

In the same environment ideal for Shiitake (i.e. normal light, CO2 less than 1000 ppm), strains of H. tessulatus produce a stem less than 2 inches tall and a cap many times broader than the stem is long. When the light is reduced and the carbon dioxide levels are elevated, the mushrooms metamorphosize into the form preferred by the Japanese. Here again, the Japanese have set the standard for quality.

In the growing room, abbreviated caps and stem elongation is encouraged so that forking bouquets emerge from narrow mouthed bottles. Modest light levels are maintained (400 lux) with a higher than normal carbon dioxide levels (>2000 ppm) to promote this form of product. From a cultivator's point of view, this cultivation strategy is well merited, although the mushrooms look quite different from those found in nature. This cultivation strategy is probably the primary reason for the confused identifications. When visiting Japan, American mycologists viewed these abnormal forms of H. tessulatus, a mushroom they had previously seen only in the wild, and suspected they belonged to Lyophyllum.

Many of the strains of H. marmoreus cultivated in Japan produce dark gray brown primordia with speckled caps. These mushrooms lighten in color as the mushrooms mature, becoming tawny or pale woody brown at maturity. Most strains obtained from cloning wild specimens of H tessulatus from the Pacific Northwest of North America are creamy brown when young, fading to a light tan at maturity, and have distinct water-markings on the caps. The differences seen may only be regional in nature.

This mushroom does not exude a yellowish metabolite from the mycelium typical of Pleurotus species. However, it has been found that H. tessulatus produces a mycelium-bound toxin to nematodes, similar to that present in the droplets of P. ostreatus mycelium. This discovery may explain why it is not likely to see a nematode infestation in the course of growing Hypsizygus tessulatus.

Given the number of potentially valuable by-products from cultivating this mushroom, entrepreneurs might want to extract the water soluble anti-cancer compounds and/or menatacides before discarding the waste substrate.

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