52

Scientific Name

Ostyra spp.

Ostyra carpinifolia Ostrya virginiana

Pasania

Platycarya strobilacea

Populus spp.

Populus balsamifera Populus deltoides Populus fremontii Populus grandidentala Populus heterophylla Populus nigra Populus tremuloides Populus trichocarpa Prosopis spp.

Prosopis juliflora Prosopis pubescens Quercus spp.

Quercus acuta Quercus acutissima Quercus agrifolia Quercus alba Quercus aliena Quercus bella Quercus brandisiana Quercus chrsolepis I Quercus crispula ' Quercus dentata Quercus emoryi Quercus fabri Quercus falcata Quercus gainbelii Quercus garryana Quercus glandulifera Quercus glauca Quercus grosseserrata Quercus kelloggi Quercus kerii Quercus kingiana Quercus lobata Quercus laurifolia

Common Name

Scientific Name

Common Name

Ironwoods

Quercus lyrata

Overcup Oak

(Hophornbeam)

Quercus michauxii Quercus mongolica Quercus muehlenbergii Quercus myrsinae

Swamp Chestnut Oak

Quercus nigra

Water Oak

Cottonwoods &

Quercus nuttalli

Poplars

Quercus palustris

Pin Oak

Balsam Poplar

Quercus phellos

Willow Oak

Eastern Cottonwood

Quercus prunis

Fremont Cottonwood

Quercus rubra

Northern Red Oak

Bigtooth Aspen

Quercus semiserrata

Swamp Cottonwood

Quercus serrata

Black Poplar

Quercus spinosa

Quaking Aspen

Quercus variabilis

Live Oak

Black Cottonwood

Quercus virginiana

Mesquite

Rhus spp.

Sumac

Honey Mesquite

Rhus glabra

Screw Pod Mesquite

Rhus succedanea

Oaks

Robinia spp.

Black Locust

Robinia neomexicana

New Mexico Black

Locust

Californa Live Oak

Robinia pseudoacacia

Black Locust

White Oak

Salix spp.

Willows

Salix amygdaloides

Peachleaf Willow

Salix exigua

Sandbar or Coyote

\ zs

^ \ fi“

Willow

U o

OSamj^n Live Oak

Salix fragilis

Crack Willow

Salix geyerana

Geyer Willow

Salix lasiandra

Pacific Willow

Emory Oak

Salix lasiolepis

Arrow Willow

Salix nigra

Black Willow

Southern Red Oak

Salix scoulerana

Scouler Willow

Gambel Oak

Sapium discolor

Oregon White Oak

Sloanea sinensis

Taxus spp.

Yews

Taxus brevifolia

Pacific Yew

Clmus spp.

Elms

California Black Oak

Ulmus americana

American Elm

Ulmus campestris

English Elm

Ulmus laevis

Fluttering Elm

California White Oak Laurel Oak

Ulmus montana

Mountain Elm

MATERIALS FOR FORMULATING A FRUITING SUBSTRATE 53

Cereal Straws For the cultivation of Oyster mushrooms, cereal straws rank as the most usable base material. Wheat, rye, oat and rice straw perform the best. Of all the straws, I prefer wheat. Inexpensive, readily available, preserving well under dry storage conditions, wheat straw admits few competitors. Furthermore, wheat straw has a nearly ideal shaft diameter which selectively favors the filamentous cells of most mushrooms. Chopped into

1- 4 inch lengths, the wheat straw needs only to be pasteurized by any one of several methods. The approach most easily used by home cultivators is to submerge the chopped straw into hot water ( 1 60° F., 7 1 0 C.) for 1 -2 hours, drain, and inoculate. First, fill a metal barrel with hot tap water and place a propane burner underneath. (Drums should be food grade quality. Do not use those that have stored chemicals.) A sec ond method calls for the laying of straw onto a cement slab or plastic sheeting to a depth of no more than 24 inches. The straw is wetted and turned for 2-4 days, and then loaded into a highly insulated box or room. Steam is introduced, heating the mass to 1 60° F. (7 1 0 C.) for

2- 4 hours. (See Chapter 18 for these methods.)

The semi-selectivity of wheat straw, especially after pasteurization, gives the cultivator a two-week “window of opportunity” to establish the gourmet mushroom mycelium. Wheat straw is one of the most forgiving substrates with which to work. Outdoor inoculations of pasteurized wheat straw with grain spawn, even when the inoculations take place in the openair, have a surprisingly high rate of success for home cultivators.

Rye straw is similar to wheat, but coarser. Oat and rice straw are finer than both wheat and rye. The final structure of the substrate depends upon the diameter and the length of each straw shaft. Coarser straws result in a

Figure 38. Oyster mushrooms growing from my previous book, The Mushroom Cultivator.

looser substrate whereas finer straws create a denser or “closed” substrate. A cubic foot of wetted straw should weigh around 20-25 lbs. Substrates with lower densities tend to perform poorly. The cultivator must design a substrate which allows air-exchange to the core. Substrate dynamics are determined by a combination of all these variables.

Paper Products (Newspaper, Cardboard, Books, etc.)Usingpaperproducts as a substrate base is particularly attractive to those wishing to grow mushrooms where sawdust supplies are limited. Tropical islands and desert communities are two examples. Paper products are made of pulped wood, (lignin-cellulose fibers), and therefore support most wood-decomposing mushrooms. In recent years, most printing companies have switched to soybean-based inks, reducing or almost eliminating toxic residues. Since many large newspapers are

ments and hundreds of others are listed in Appendix V. Using rice bran as a reference standard, the substitution of other supplements should be added according to their relative protein and nitrogen contents. For instance, rice bran is approximately 12. 5 % protein and 2% nitrogen. If soybean meal is substituted for rice bran, with its 44% protein and 7 % nitrogen content, the cultivator should add roughly 1/4 as much to the same supplemented sawdust formula. Until performance is established, the cultivator is better off erring on the conservative side than risking over-supplementation.

A steady supply of supplements can becheaply obtained by recycling bakery waste, especially stale breads. A number of companies transform bakery by-products into a pelletized cattle feed, which also work well as inexpensive substitutes for many of the additives listed above.

Whichever materials are chosen for making up the substrate base, particular attention must be given to structure. Sawdust is uniform in particle size but is not ideal for growing mushrooms by itself. Fine sawdust is “closed” which means the particle size is so small that air spaces are soon lost due to compression. Closed substrates tend to become anaerobic and encourage weed fungi to grow.

Wood shavings have the opposite problem of fine sawdust. They are too fluffy. The curls have large spaces between the wood fibers. Mycelium will grow on shavings, but too much cellular energy is needed to generate chains of cells to bridge the gaps between one wood curl and the next. The result is a highly dispersed, cushionlike substrate capable of supporting vegetative mycelium, but incapable of generating mushrooms since substrate mass lacks density.

The ideal substrate structure is a mix of fine

and large particles. Fine sawdust particles encourage mycelia to grow quickly. Interspersed throughout the fine sawdust should be larger wood chips (1-4 inches) which figure as concentrated islands of nutrition. Mycelium running through sawdust is often wispy in form until it encounters larger wood chips, whereupon the mycelium changes and becomes highly aggressive and rhizomorphic as it penetrates through the denser woody tissue. Tire structure of the substrate affects the design of the mycelium network as it is projected. From these larger island-like particles, abundant primordia form and can enlarge into mushrooms of great mass.

For a good analogy for this phenomenon, think of a camp fire or a wood stove. When you add sawdust to a fire, there is a flare of activity which soon subsides as the fuel bums out. When you add logs or chunks of wood, the fire is sustained over the long term. Mycelium behaves in much the same fashion.

Optimizing the structure of a substrate is essential for good yields. If you are just using fine sawdust and wood chips (in the 1-4 inch range) then mix 2 units of sawdust to every 1 unit of wood chips (by volume). (Garden shredders are useful in reducing piles of debris into the 14 inch chips.)

Although homogeneity in particle size is important at all stages leading up to and through spawn generation, the fruitbody formation period benefits from having a complex mosaic of substrate components. A direct relationship prevails between complexity of habitat structure and health of the resulting mushroom bed.

A good substrate can be made up of woody debris, chopped corncobs and cornstalks, stalks of garden vegetables, vines of berries or grapes. When the base components are disproportionately too large or small, without connective particles, then colonization by the mushroom mycelium is hindered.

M ushroom strains vary in their ability to convert substrate materials into mushrooms as measured by a simple formula known as the “Biological Efficiency (B. E.) Formula” originally developed by the White Button mushroom industry. This formula states that

31 1 lb. of fresh mushrooms grown from 1 lb. of dry substrate is 100% biological efficiency.

Considering that the host substrate is moistened to approximately 75% water content and that most mushrooms have a 90% water content at harvest, 100% B. E. is also equivalent to ' m growing 1 lb. of fresh mushrooms for every 4 lbs. of moist substrate, a 25% conversion of wet substrate mass to fresh mushrooms or

m achieving a 10% conversion of dry substrate mass into dry mushrooms.