Published Oct 31, 2013

Fungus Among Us- Beginning Farmer Photo Essay

By Marc Strobbe

As a member of Practical Farmers’ Savings Incentive Program Will Lorentzen is exploring a business based on vegetables, free range livestock, and mushrooms. He is also working to create a mushroom grower’s cooperative for Iowa farmers. Will’s passion for mushroom cultivation is readily apparent, as is his joy at sharing it with others.

So much of the story is left untold by these photos, they show the end result of weeks of inoculation in the case of the shiitake and one day a week with the oysters.

The shiitakes start with selecting the right trees to cut for the logs, oaks are best but several other hardwoods work well also. Trees must be cut after all the leaves have fallen and before they grow back, when the tree is dormant, otherwise the bark will slip. Holes are drilled in the logs and filled with pegs or sawdust that is colonized with the desired train of mushrooms. These pegs or sawdust are called spawn. Next the holes are waxed shut using hot cheese wax, veggie wax, or beeswax. Finally the logs are arranged in a crib stack (Pic #1) if they are warm weather or wide-range varieties. If they are cold weather strains lean them on a line or rail (Pic #2) and wait.

Depending on the strain they will start to fruit on their own six to eighteen months later (Pic #3). At that point you can “force fruit” them for the predictable harvest needed for commercial production. This is done by soaking the logs for 24-36 hours, then leaning them on a rail and thumping them with a rubber mallet. Depending on temperature and moisture they are harvest-able about two weeks later, then they need to rest for a couple months.

Cold weather strains do not do well with forcing and stay leaning together in place for the life of the log. They typically fruit in early spring and late fall, further extending the season. Shiitake logs typically last one year per one inch of thickness. They usually sell for $12 per pound retail and 9$ per pound wholesale.

Oyster mushrooms are much quicker, with a colonization period of 2-4 weeks depending on strain and ratio, but it is a little more complicated. The medium, in my case straw, needs to be pasteurized using heat or chemical means, such as hydrogen peroxide or builders lime. The spawn, usually colonized grain or sawdust, is pitched into the pasteurized medium and mixed thoroughly. Finally the inoculated medium is stuffed into bags (Pics #4 and #6) or buckets (Pic #5) and set in a cool dark place to wait.

I have been looking into more reusable and sustainable containers for the grow out. The buckets work great and the clusters are easy to harvest. Once tiny mushrooms appear the containers are set in a prepared production location. With proper irrigation harvest-able mushrooms will flush within a week. Each bag or bucket will flush 3 times before it is spent. Oyster mushrooms generally go for $14 per pound retail and $8 per pound wholesale.

My mushroom production building is meant to control temperature and pests in order to prolong the ideal production conditions. Pic #5 shows the white covering on the south-facing side to diffuse the light to help keep it cooler inside the building than outside. I could put a heater to extend the season further, but right now I just push as hard as I can during the season I am given. I am currently trying to keep it as low tech as possible, and always experiment to find ways to make it a less intimidating crop to grow for other beginning farmers.