Growing Rice Straw Mushrooms

Sheryl:  One of the edibles I found interesting in Cambodia was what they call Rice Straw Mushrooms which are grown above ground but nowhere could I find the exact science so I called on another rare fruiter Paul William who lives in San Francisco who knows his fungi and the following article is what he sent me. I also rang Tom May, a fungi expert who works at the Botanical Gardens in Melbourne as I couldn’t source this particular mushroom here in Brisbane and he said that it had been found recently in lawns in Darwin and was written up in 2006 in Australian Mycologist Volume 25 Part 2 page 65.

To summarize the bible of mushroom cultivation, "Growing Gourmet and Medicinal Mushrooms" by Paul Stamets, the Paddy Straw Mushroom (Volvariella volvacae) are prodigiously fast-growing and thrives at 75-95 F. (24-35 C.) and dies below 45/7 (F/C) degrees.  It is growable outdoors, using simple, low-tech methods (in contrast to most other mushrooms).  The time from inoculation to fruiting is "awesomely fast, giving competitors (mould) little opportunity to flourish.  After the rice harvest, farmers mulch their rice straw into mounds and inoculate with commercial spawn.

Substrates for Fruiting: "Straw, preferably rice, hardwood sawdusts.  Wheat straw also supports fruitings, although not nearly as well as supplemented composted rice straw.  Once study showed that the best supplement for wheat straw is wheat bran (5%) and/or cotton hulls (10%).  The pH optimum for fruiting falls between 7.5 and 8.  This mushroom can be grown on uncomposted staw-based substrates, although yields are substantially improved is the substrate is "fermented" or short-cycle composted.   If the rice straw is composted with supplements for 4-5 days, pasteurized and inoculated, yields can be maximized.  The heat generated within the composting straw/cottonseed hull mass accelerates the growth of the thermophilic and heat-tolerant Volvariella volvacae.

Soaked straw is thrown into a tapering, trapezoid-shaped, open top and bottom, plywood form.  Soaked cottonseed hulls are thrown around the outer inside edge of the frame, and then inoculated with grain spawn.  Additional layers of straw/cottonseed hulls are layered down inside the wooden form in the same fashion.  After 4-6 layers, the frame is lifted off.    The mounds may be covered with plastic, or with heavy layers of straw which is kept moist.  In as short as 7 days, mushrooms form. A plastic tunnel can help to maintain humidity and warmth."

The most comprehensive English book on the cultivation of this mushroom is by S.T. Chang, published in 1972 entitled "The Chinese Mushroom (Volvariella volvacae): Morphology, Cytology, Genetics, Nutrition and Cultivation".

 

Authored by: 
Paul William
Sourced from: 
Sub-Tropical Fruit Club of Qld. Inc Newsletter June - July 2007
Date sourced: 
27/03/2013