Learn about oyster spawn, including some of the top strains and species, and it will be easier for you to grow your own oyster mushrooms at home

The strain used and oyster spawn source is crucial to the success of any grower. Mushroom strains are different individuals of a certain species. Similar to how all people are Homo sapiens but each of us has a unique set of genetic information, which results in a unique expression of traits. In a mushroom the expression of different traits can mean a variety of things. Morphology, yield, preference and ability to grow on certain substrates, storability, speed of colonization, environmental parameters for fruiting and ability to withstand competing organisms all can be determined by strain.

Strains can be discovered or developed through two approaches. The first is through finding and isolating a fruiting body in the wild. These strains need to be trialed and observed to learn their particular expression of different traits. Some of these traits can be observed when the wild mushroom is found. Recording data like the substrate found on, fruiting temperature, region, fruit body shape and color, size of fruiting is very valuable. Strains can also be developed and selected for certain traits through sexual reproduction in a laboratory. Certain desired traits like high yield and wide fruiting temperature can be encouraged through breeding. Strains with a history of use and distinct recorded traits are highly valuable to every grower.

Here is a look at oyster spawn strains I like:

1) Blue Oyster Amycel 3015: This strain produces clusters of mushrooms with large caps whose color ranges from blue to white. The mycelial growth is fast and fruiting can happen within a wide range of temperatures between 50-75 degrees Fahrenheit.

2) Blue Oyster Lambert 123: Another strain that is high yielding with fast mycelial growth. The mushrooms grow clusters, which are small and dense. This makes packaging easier.

3) Blue Oyster Pearl: This beautiful blue oyster is best grown at lower temperatures, between 50-65 degrees Fahrenheit. The caps tend to be large and thick when grown at low temperatures.

4) Yellow Oyster AM1: This vibrant yellow oyster mushroom likes to fruit at higher temperatures between 60-80 degrees Fahrenheit. The caps are typically small and numerous, with a large edible stem mass. The yields run medium to high.

5) White Oyster Elm A: This white oyster colonizes aggressively, helping keep contaminants out. The fruiting temperature ranges from 55-80 degrees Fahrenheit. The caps are large and the mushroom can fruit singularly or as clusters.

6) Pink Oyster VDE-1: This strain produces pink to red fruiting bodies between the temperatures of 60-85 degrees Fahrenheit. This mushroom cannot survive temperatures below 40 degrees F. This strain is extremely fast colonization and it has the ability to grow on a wide range of substrates.

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Understanding types of oyster spawn: Sawdust and grain

Oyster spawn type and source has a large impact on yields. The two most common types of oyster spawn used in cultivation are sawdust and grain spawn.

Grain spawn gives one major advantage by supplying a pre-colonized nitrogen source to the substrate. This can help to increase yields of low nitrogen substrates like straw or paper waste. Smaller grains like millet are preferred to larger grains like rye or wheat as they allow for more inoculation points from the same amount of inoculum. One pound of rye spawn may have about 200 particles for the mycelium to leap off from while millet will have closer to 500. By using millet, a smaller grain, the mycelium will spread more evenly and abundantly through the substrate. Sawdust spawn can be better than larger grains because of the small particle size.

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Sourcing oyster spawn is an important consideration

Source of the oyster spawn will also factor in to the success of growth and yield achieved in cultivation. Oyster spawn grown or purchased should be free of any detectable contamination. Smell or sight can be used to detect contamination. A bacterial or yeasty smell to the mycelium indicates oyster spawn that should not be used. If patches of green, pink, red, orange, black, or other colors different from the rest of the mycelium are observed, the oyster spawn should not be used. It is tempting to try and remove a small patch of mold on spawn and use it anyways but this will not work. If the mold or bacteria is visible anywhere in the spawn it is present throughout the entire bag. If using aseptic technique, spawn that has been opened outside of the lab should not be used, as airborne contaminants are sure to be present and expanded into the new substrate.

It is important to understand that contamination is not a definitive yes or no answer.

Contamination is more like a spectrum than a black and white decision. For this reason it is critical to track yields and weight of the substrate the mushrooms are grown on. From this information biological efficiency (B.E.) can be found. This is the comparison of fresh mushrooms harvested to dry weight inoculated. Through tracking B.E. a grower can tell if they have contamination even if it cannot be detected. All of the mycelial growth happens on a microscopic level so it is impossible to know through normal inspection exactly what is happening. Only through the tracking of B.E. will a grower truly know if contamination exists.

It is possible for new growers and small growers to grow their own oyster spawn but it will not be the same quality as what is produced in a commercial lab. The level of sterility and effectiveness of the equipment in these labs makes their spawn capable of giving a grower the best yields. If a mushroom grower is going to grow their own oyster spawn they should trial it using the same strain against a commercial spawn producer to see if yield is any different.