Forecasting matsutake mushroom formation has been a guessing game for all. Many have considered fall rains to be a primary influence. Yet recent studies have noted bumper and banner crop years with little or no rain  prior to, and during fruiting. The influence of rain considered to be only a cooling agent, beginning formation, or fruiting ( Alexander, Pilz , et al, Environmental Management Vol. 30, No 1, pp. 129-141). Studies conducted in 1995, near Diamond Lake, clearly indicated moisture effects were confined to mushroom size.

Fall temperature changes have been documented as a major influence in all stages of production. Subsequent forecasts based on these changes have been considered 100% accurate (5 areas, 60 years examined, Canada, California, and Oregon).

Temperatures changes cause of mushrooms to form, grow and can cause a flush. Temperature changes are an easily monitored, reasonably accurate method to determine volume, location, and time of emersion. Temperatures likely initiate biological, chemical, or mycological changes, in host and/or mycelia matt. These changes are unknown to scientist I questioned.

The ideal formation would consist of rain and cooling, followed by a 6 to 9 degree warming for as long as possible, a deeper cooling, accompanied by rain, and a warming, with cold nights and moderately warm days. Some of the best crops in the Central Oregon Cascades have occurred with all most no rainfall. 1997 is one of those seasons around Chemult and Crescent Oregon.

The general needs are easy to understand. Cooling begins the process, warmth forms pens (tiny mushrooms), deeper cooling begins flush, warming promotes fruit growth. Changes such as too much warming, extended cooling, or too deep cooling, at any stage, will limit or stop production.

Forecasting is also closely tied to forest farming. Manipulation of canopy closure is "fruitless" if formation patterns only occur every 5 or 6 years. Some areas are known to fruit every 8 - 10 years.

The following graphs show relations between falling fall temperatures and fruit production in hardwood habitat. Three day average air temperature is used to plot points. Seven day averages are used to plot in pumice soils, Cascades. Pumice soils cool much slower. A statistical evaluation is available.