Morel Cultivation

Indoor morel cultivation at Gourmet Mushrooms Inc. in Scottville, MI.

Around this time of year here in Michigan, many morel fanatics are heading into the woods in search of this prized fungus. Many people I know have coveted sites where they collect morels year after year. The locations of many of these morel hunting grounds are kept as closely guarded secrets passed down through families. I can understand why this is done, morels can be difficult to find and are incredibly delicious; prized by both amateur hunters and gourmet cooks alike.

Morels are the fruiting bodies of species of the fungal genus Morchella. The higher fungi are made up of two main divisions, the basidiomycetes and the ascomycetes. Most of the common edible fungi belong to the basidiomycetes, which have a typical “mushroom” morphology. However, morels are unusual in that they are cup fungi relatives in the ascomycetes, which also include truffles and bakers and brewer’s yeasts. Although there is some disagreement on the nuances of morel taxonomy, the general consensus is that there are three main clades of morels: the Elata clade (black morels), the Esculenta clade (yellow morels) and the Rufobrunnea clade (blushing morels). Within these clades there are many different species that can be difficult to distinguish and whose distinctions are debated by experts (1).

In Western North America the annual commercial value of morels is between $5 and $10 million, making them one of the more valuable forest products, and because of difficulties in cultivation in many markets sales of wild collected morels still outpace that of cultivated products (2). As of 2007, the largest exporters of dried morels were India, Pakistan, Turkey, Nepal, Bhutan, the United States, Canada, and China, while Europe made up the largest import market (2). Although morels can be abundant outdoors, they can be hard to find, product is limited, and finding sufficient yields can be timely and labor intensive. Because of these drawbacks and their desirability in gourmet cooking, attempts have been made to cultivate morels, both in outdoor fields and in indoor growing facilities.

Outdoor morel cultivation is typically performed in farmland or forests, with China being the biggest producer. Dim light is required so morels are either grown in the shade of the forest or using a shade covering. The morel spawn is planted directly into the ground in the fall with harvest the following spring. There have been two major developments leading to the increase in farmed morel production, the development of higher yielding strains, typically from the Elata/black morel clade and the use of exogenous nutrient bags (3). The nutrient bags are plastic bags filled with plant-based nutrients (grain, rice hulls, etc.) that are cut and placed on the soil to serve as a longer-term additional nutrient source (4). Despite these improvements in cultivation techniques the product is still seasonal, labor intensive and vulnerable to climate and pests (3).

In order to overcome these limitations, we have been piloting indoor cultivation of morels in our facility at Gourmet Mushrooms, in Scottville, MI, to produce fresh morels year-round. An indoor morel cultivation method was first developed in the 1980s by Gourmet Mushrooms’ own Dr. Gary Mills and colleagues (5), involving growing morels in trays. The morel cultures are inoculated from an agar plate culture into bags with a layer of cooked grain and a top layer of hydrated soil, which promotes the formation of sclerotia. Sclerotia are a mass of fungal tissue that serves as a nutrient reserve, with proper sclerotia formation critical to morel cultivation. The cultures incubate for 5 weeks, until the hardened sclerotia mass is formed. After which the sclerotia is planted in trays with compost and nutrient supplements. Once planted the morel trays are incubated in a climate-controlled room and regularly watered. Seven days after planting the cultures are induced by heavy watering in order to hydrate the sclerotia and stimulate hyphal growth from the sclerotia, critical to fruiting. A few days after induction the conidia, or asexual spores, begin to form, followed by the formation of primordia, which will continue to grow into a fully mature morel fruit body. After 38 days of cultivation the morels are harvested.

No matter where they come from morels are always delicious. I like them simply fried up in butter on high heat, Wolfgang Puck likes to put them in omelets, they are also great in pasta sauces and soups. Further, studies have suggested morels have medicinal properties, including anti-tumor, anti-inflammatory and neuroprotective effects (3,6).

Citations:

1. Richard, F. et al. True morels (Morchella, Pezizales) of Europe and North America: evolutionary relationships inferred from multilocus data and a unified taxonomy. Mycologia 107, 359–382 (2015).

2. Pilz, D. et al. Ecology and management of morels harvested from the forests of western North America. USDA For. Serv. - Gen. Tech. Rep. PNW-GTR 1–165 (2007). doi:10.2737/PNW-GTR-710

3. Liu, Q., Ma, H., Zhang, Y. & Dong, C. Artificial cultivation of true morels: current state, issues and perspectives. Crit. Rev. Biotechnol. 38, 259–271 (2018).

4. Tan, H. et al. Multi-omic analyses of exogenous nutrient bag decomposition by the black morel Morchella importuna reveal sustained carbon acquisition and transferring. Environ. Microbiol. 21, 3909–3926 (2019).

5. Ower, R. D., Mills, G. L. & Malachowski, J. A. United States Patent: cultivation of Morchella. (1986). doi:10.1016/j.(73)

6. Nitha, B., Meera, C. R. & Janardhanan, K. K. Anti-inflammatory and antitumour activities of cultured mycelium of morel mushroom, Morchella esculenta. Curr. Sci. 92, 235–239 (2007).