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Preparing For Inoculation

Picking The Right Shiitake Strain

 

If you inoculate the logs yourself, order your spawn (the form of the shiitake fungus that grows through the log) from a reputable dealer 1 to 2 months before you plan to cut your trees. Spawn producers may not have the most desirable strains available if you wait too late to order. Give the spawn dealer your desired shipping date so your spawn will be as fresh as possible.

 

Fruiting Temperature Requirements

 

There are several shiitake strains (varieties) available. They are usually categorized by fruiting temperature requirements. Shiitake will generally fruit (form the edible mushrooms) at log temperatures between 41 and 86 degrees F.

 

· Cool season strains fruit at 41 to 68 degrees F.

· Wide range strains fruit at 50 to 80 degrees F.

· Warm season strains fruit between 50 and 86 degrees F.

 

Strains may also vary in productivity, appearance, mushroom size and length of time it takes to fruit.

 

Environment

 

Select strains that will fruit in the environment where you plan to develop your shiitake garden. If you plan to use the shade of a maple tree, inoculate logs with a warm season strain for summer fruiting. If you want to harvest mushrooms in winter, inoculate logs with a cool season strain. A wide range strain can be used for spring and fall production. Logs grown indoors should be inoculated with a strain that grows at the temperature of the growing room you plan to use.

 

Condition and Appearance Of Spawn

 

All strains can be purchased as sawdust or dowel spawn (Figure 1). Your spawn should be white and fluffy when you receive it (Figure 1). There should be little or no liquid in the bottom of the bag. If there are green patches (Trichoderma, a weed fungi), contact the vendor and ask for new spawn.

 

Figure 1. Dowel (left) and sawdust spawn (right) are used for log inoculation.

 

 

If the spawn is brown and loose, the mycelium is not well knitted and it was sent to you before it was ready for you to use. You can store unknitted spawn at about 65 to 70 degrees F in a moist environment for a few weeks, to see if it will turn white, or you can return it and ask for your money back or a white bag of spawn. If you receive your spawn more than a few days before you plan to inoculate, you should place it in the refrigerator or a very cool basement. Move spawn to room temperature about 24 hours before you plan to inoculate. When ordering a preinoculated log or sawdust block, make sure you tell the supplier the fruiting temperature conditions, so you will get the right inoculated strain.

 

Selecting The Best Trees

 

Type

 

The three types of trees most often used for production of shiitake mushrooms are white oak, red oak, and sweetgum. White oaks are the most productive and are bothered the least by invasions of foreign or weed fungi. But, white oaks require the most patience, since it usually takes 8 to 12 months from inoculation before the mushrooms first begin to fruit.

 

Red oak and sweetgum have softer wood and will produce mushrooms in 6 to 8 months. They also require more careful management since they are more susceptible to other fungi, bark peeling, and rapid water loss.

 

Shiitake mushrooms will also grow on American hophornbeam, ironwood, laurel oak, cherry, sassafras, sycamore, tulip poplar, and hickory. How well the shiitake mushrooms grow on logs from these trees depends on how much care you give the logs and how well you control moisture, temperature, and exposure to other fungi. Other types of trees can be used for growing shiitake mushrooms, but under the best of conditions, you will only harvest a few mushrooms per log.

 

The actual location of the growing tree is also important. The more fertile soils will produce trees with more nutrients and sugars. Trees located on rocky hillsides and in very wet sites are less nutrient rich.

 

Area Of Sapwood

 

Since shiitake mushrooms feed primarily on sapwood, trees selected for inoculation should have a large sapwood area. You can determine the area of sapwood by looking at the end of a log after the tree has been cut. Most of the trees in a particular area will have similar sapwood to heartwood ratios. The lighter or outermost wood is the sapwood and the darker or inner wood is the heartwood (Figure 2). A small amount of sapwood means that the log will probably produce mushrooms for less than 2 years.

 

Figure 2. The lighter, outermost wood is the sapwood and the darker, inner wood is the heartwood.

 

 

Cutting And Buying Shiitake Logs

 

Cutting

 

Logs should be harvested during the dormant season from live, healthy trees. Cutting your own logs is an option only if you have a chain saw and easy access to hardwood trees. Be sure you take a buddy along if you cut your own logs. If you can, cut the tree down 7 days before you plan to inoculate. Logs can then be cut to size and moved to the inoculation site immediately.

 

Trees left in the woods should remain uncut and untrimmed for 7 to 10 days. Then, cut them to size and inoculate within a few days. The diameter and length of the log will depend on how heavy you want your logs. A log 40 inches long, 8 inches in diameter will weigh about 60 pounds. A log 40 inches long, 4 inches in diameter will weigh about 25 pounds.

 

Buying

 

Buying logs to inoculate can be difficult because the logs must not be split or the bark damaged. They must also be of the type, length, and diameter you specify. Most log cutters will charge from $0.50 to $1.00 for a log 40 inches long and 4 to 6 inches in diameter. Agree to accept and pay for only those logs meeting your specifications.

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