Inoculating Logs - Cornell Small Farms (2024)

EXPERT OPINION: Inoculation Methods

“Sawdust spawn allows the inoculator to work faster than with a dowel and hammer. Also, I believe that sawdust spawn leaves less room for contamination because the spawn is not touched by your hands.”

- Nick Laskovski, Dana Forest Farm

EXPERT OPINION: Strain Choice

“Most growers in cooler climates tend to use Wide Range strains in the majority of their logs. I recommend that people always start here and then branch out into the WW and CW strains.”

- Steve Gabriel, Wellspring Forest Farm, Mecklenburg NY

EXPERT TIPS: Cold Weather Strains

“I’ve been using the cold weather strain Snowcap for several years (from Field and Forest), and have been harvesting them for more than two weeks (they started pinning in early April) - with no cover. They sailed right through the last cold snap (low-20s, daytime temps not much above freezing) and are coming on strong now.

“I am shocking 20 logs per week of those that didn’t ‘wake up’ naturally, and they are also pinning happily now.

“For people in the North Country like me (20 miles from Canada/we get below-40-degree nights right into June, and again by late August), you might consider diversifying your strains.

“I highly recommend SNOW CAP, and also BOLSHOI BREEZE. Both can keep fruiting right into November - and tend to pick up when the WR and Warm-weather strains poop out.”

-Robert Wagner, North Woods Shiitake

Spawn Type

Bolts can be inoculated with sawdust spawn, plug spawn, or thumb spawn. There are advantages and disadvantages to each. Plug spawn is very simple to use—the only tool needed is a drill and hammer or mallet. The drawbacks are that plug spawn is slightly more expensive per log than sawdust spawn, the mycelium may take a while to migrate into the sapwood of the log, and the inoculation operation is significantly slower than the sawdust spawn method. Sawdust spawn is slightly cheaper than plug spawn, but it requires a special tool (inoculator), either purchased or homemade, to insert the sawdust into the hole. In addition to its lower cost, the mycelium contained in sawdust spawn moves out into the log more quickly, giving somewhat faster produc- tion. This guide specifically describes the sawdust spawn method, which is more common for commercial enterprises.

Choosing Spawn Strain

Mushroom supply catalogs describe strain categories that differ in the tem- perature range at which they fruit. Each category described below includes several strains (varieties) of spawn and each of these is a genetically unique clone. The differences between each strain temperature category are also summarized below. Generally speaking, we recommend trying a variety of different strains to see what works best under your specific conditions. By us- ing a combination of strains, many growers are able to maximize the length of their fruiting season.

People sometimes wonder if there is a taste difference between different strains. Although there isn’t data on the subject, commercial growers tend to find that cold weather strains produce shiitake with a more intense flavor. Try a few strains and see what you think. If you intend to try only one strain the first time around, we recommend a WR strain.

• Wide Range (WR) Strains: These are the favorite among both commercial growers and beginners. They are reliable. Fast spawn run and fruiting al- low a faster return on investment. WR strains can be force fruited easily and recover vigor more rapidly after fruiting.

• Warm Weather (WW) Strains: Warm Weather strains produce the highest quality mushrooms during the hot summer months and early fall. They respond well to soaking for commercial production, and tolerate warmer soak water than other strains. They are also often recommended for grow- ing Shiitakes on some of the softer hardwoods, such as red maple.

• Cold-Weather (CW) Strains: These tend to fruit in early spring and late fall. These strains require a longer spawn run than other stains. They won’t re- liably fruit after being forced, so most people let the natural rise and fall of wintry temperatures initiate fruiting. See side-bar for more information about cold weather strains.

Using Cold Weather Strains to Extend Season

Cold weather strains are well suited to the Northeast where the growing season is short and the time frame for fruiting wide range and warm weather Shiitake strains can be limited. Since cold weather strains fruit during the transition times from spring to summer and summer to fall, they can be used as a strategy for season extension. Even though cold weather strains do not respond well to shocking, Northeast-based growers with enough cold weather strain logs can supply late spring and fall markets when other mushroom growers can’t. Learn more about season extension using cold temperature strains on page 31.

Log inoculation is a three step process. First a series of small holes are drilled into each log. Each hole is then tightly packed with spawn. Lastly, the surface of each hole is covered with wax to ensure optimal mycelium growing conditions and reduce contamination by other fungi species. Each step is described in detail on pages 20 through 22.

This process can be quite repetitive and time consuming; however, many growers have found innovative ways to speed it up. For example, you can solicit volunteer help by hosting an inoculation party or informal mushroom inoculation class; see page 17 for more details. You may also want to consider setting up a small assembly line. Building an inoculation table is a great way to save time and your back. Ideally, you will want a table that keeps the log from rolling over when you are working with it, but also makes it easy to move the log from one station to another. Some handmade inoculation tables are pictured below to offer inspiration.

A black-and-white illustration of the inoculation process from drilling to waxing. Drawing by Carl Whittaker.