by Bill and Mary Weaver
Wisconsin mushroom grower Jeremy McAdams, owner of Cherry Tree House Mushrooms, takes pride in growing his Shiitake and other fancy varieties of mushrooms organically, on logs, with minimal waste and using biodegradable packaging. A former architect, he believes that local, organic, sustainably grown produce is the wave of the future. McAdams started small in his backyard in Minneapolis. Now, only six years later, he has hopes of making a living for his family on their small farm, with two large fruiting houses of mushrooms at the center of the farm business.
After several moves prompted by his operation’s growth, he is now located in Clayton, WI, and has 4,000 oak logs inoculated with mycelium. “I drill the holes for inoculation closer together than some growers,” he commented. “I plan to have a steady supply of Shiitakes from spring through fall.”
After inoculation, although many growers seal the holes with cheese wax, McAdams has found a tool that “enables us to cap the logs much more efficiently with foam caps. We’re working to develop a substitute for foam that can also be used with this tool.”
Shiitakes fruit naturally in spring and fall. To induce summer fruitings, McAdams soaks logs weekly in cold water that is at least 20 degrees colder than ambient temperatures. “It’s unique to Shiitakes that you can force-fruit by soaking. Because I now mostly sell through distributors, using this method is helpful to me. I wouldn’t recommend forced fruiting for smaller growers with, say, 100 logs.
“I give a log two months off between soakings so that usually means a log gives two fruitings each summer with a pound or so of Shiitakes per fruiting.” Forcing fruiting may reduce the useful life of a log.
One satisfying thing about growing mushrooms on logs is that the logs used, which are four-, six- or 8- inches in diameter and can vary in length from about 36 inches to 48 inches, are a size that timber companies leave behind as waste. Mushroom growing makes these logs useful.
Organic, log-raised Shiitakes can have an excellent demand in the right markets. The Shiitake Growers Association (ShiiGA), although “spawned” in Wisconsin, now reaches well outside the Mid-West, with an informative website, www.SHiiGA.org . There are serious growers in many other states, with university research having been done on growing Shiitakes at Penn State, Cornell, North Carolina, Alabama and Idaho, among others.
“With the 48-inch oak logs that I use,” McAdams said, “I can expect about five pounds of Shiitake mushrooms during the life of the log. I inoculate with an aggressive Shiitake strain in spring, and harvest a small harvest that fall. The second year, the harvest is greatest, about two and a half pounds per log. The third year the harvest is a bit lower, and then yields drop in succeeding years.”
Logs for inoculation must be green, living wood that is cut either in the fall after the sap flow has stopped (about when half the leaves have turned color), or in the winter or early spring before the sap flow has restarted, with the bark intact. ShiiGA is helping to link mushroom growers and woodland owners.
The logs must be shaded to keep them from drying out after inoculation. (Tarps are used in winter after cutting to keep logs from freeze drying). “At first I used shade cloth. The logs must also be watered regularly in dry weather.” McAdams held a successful crowd funder on Kickstarter to finance a specialized hoop “fruiting house” to make shading and cooling the logs more efficient, and to prevent the developing mushrooms from drying out or becoming saturated with rain. “I think it’s important to grow in a hoop house if you’re selling to grocery stores where top quality really matters,” he commented.
In his hoop house, which has opaque white sides, the logs stand in a vertical position, to produce the best-shaped mushrooms. Now that his system is set up efficiently, McAdams plans to more than double the number of logs in the hoop house next year by closer spacing of the vertical logs, and also by constructing a second fruiting house that will use the same closer log spacing. “We want to be able to fruit more logs each week to increase production,” he explained.
In the hoop house, the logs are irrigated regularly, simulating rain. The regular irrigations help to keep the logs cooler. “I use no cooling equipment,” he noted. Also, in summer, logs freshly soaked to force fruiting are covered with damp wool fruiting blankets. “The fruiting blankets are sprayed with water every day, and this, combined with good air movement, produces evaporative cooling so that even when the temperature is 80-85 degrees in the fruiting house, the logs themselves are about 10 degrees cooler.
“When I start to see ‘pins’ under the fruiting blanket, I pull the blankets, but continue irrigating regularly. At that point, the mushrooms can tolerate up to 90-degree temperatures. In the peak of summer, it’s usually six to seven days from when I pull the blankets until I can harvest the Shiitakes for one to three days from these logs.”
McAdams dries any excess mushrooms and uses them in his popular value-added mixes and mushroom butters. He also grows several other types of mushrooms, including Namekos on black cherry logs.
Ingrid West of Misty Dawn Farm, is a smaller, but also very successful, grower of Shiitakes. “I sell all I can produce to local restaurants and farmers markets,” she stated. The current president of ShiiGA, West inoculated 250 logs from her own woods two years ago and another 250 logs this past year, to make use of the smaller logs the timber company left behind during her Managed Forest Timber Stand Improvement. West fruits her logs vertically in three carports covered with 90 percent shade cloth.
West was awarded a SARE grant, shared with Field and Forest Products, funding useful experiments. Although Shiitakes have traditionally been grown on oak logs, she is experimenting with the soft wood of aspen and red maple, harder woods like sugar maple in addition to the traditional oak, plus shagbark hickory, using different harvest times and inoculation timings.
Although this is only the second year of the experiment, some observations are already evident. On the soft aspen wood, there was a good harvest the first year, “likely because the mycelium was able to colonize the softer wood more quickly.” This might be a useful finding for new growers who need to produce a crop more quickly, but can then produce future crops on harder wood (inoculated at the same time) that takes longer to produce a crop, but has a longer productive life.
Logs were cut from fall through winter and into spring, when the sap was flowing. During sap flow is usually not a preferred time to harvest, and most likely will shorten the productive life of the log, but in West’s preliminary findings (which she stresses are anecdotal only, and will need to be verified by more research), the inoculated logs containing sap, like the softer woods, fruited more quickly. The spring log harvest timing might also make the logs more economical for growers to purchase. This preliminary research has exciting future implications. Please visit www.ShiiGA.org for more information.
Growing Shiitake mushrooms organically on logs
by Bill and Mary Weaver