Grain spawn is the most popular type of oyster mushroom mycelium among mushroom growers who grow large quantities of mushrooms. Grain spawn is used mixed with plant raw materials and these raw materials are packed into bags, from which oyster mushrooms then grow.
Why use grain spawn? This is the most convenient way to introduce mycelium evenly throughout the entire thickness of the substrate. Therefore, the mycelium hyphae spread in all directions.
The mycelium quickly overgrows, so spores of harmful microorganisms (contaminants) do not have time to conquer the substrate before the oyster mushroom mycelium.
These are fungal hyphae that have grown after inoculation of a culture (fungal strain) onto one of the carriers:
The cultures themselves are a liquid nutrient solution containing mushroom tissue that is grown under sterile conditions.
What are the types of spawn?
Depending on the material on which the mycelium is planted, it is divided into substrate, grain and on sticks.
Substrate spawning is most often done on sawdust.
Dowel spawn or also called Plug Spawn is used to inoculate wood (logs or stumps) to grow oyster mushrooms outside.
If a fungal culture is inoculated into steamed sterile grain, grain spawn is obtained.
This spawn is called the "mother" spawn. This process is carried out by specialized laboratories for growing mycelium.
When the mycelium has completely colonized the grain, the mother spawn is again inoculated into the grain: a small portion of the mother spawn is mixed with sterile grain and placed in an incubator. After complete overgrowth, laboratories sell such spawn to mushroom growers.
Why does mycelium need grain?
The grain is very nutritious and contains all the necessary substances for the full development of oyster mushroom mycelium.
Many mushroom growers believe that the best spawn comes from millet. It is small, and it has much more growing points than other types of grains.
This is true, but you need to take into account the quality of your substrate.
If you pour hot water over the raw material (hydrothermal heat treatment), some of the contaminant spores will survive.
The oyster mushroom mycelium will eat all the nutrients of a small grain of millet, but will not have time to absorb the mass of the substrate.
Then competitive molds and bacteria will have an advantage over oyster mushroom mycelium.
It seems to me that the best carrier is oat. Oats have a large but light grain. Therefore, in one kilogram of spawn there will be many more grains than, for example, wheat.
And its nutritional value is higher, especially in the surface part of the grain, where the skin is located, and it is quite thick in oats.
In many countries, rye is considered the best grain for spawning. But I haven't worked with rye, so I can't say anything.
In those countries where the predominant agricultural crop is rice, it is used for the production of spawn. And oyster mushroom grows well on a substrate of sawdust or rice straw when adding this grain spawn.
If stored incorrectly, the growth and formation of primordia occurs directly in the spawn package.
The mycelium breathes through filters. If the mycelium is of high quality and hyperactive, mushroom pins begin to form directly under the filters - after all, the largest amount of fresh air gets there.
In this photo we see the beginning of this process - a convex, round formation.
It consists of a mass of hyphae that are ready to begin producing primordia - the ovaries of fruiting bodies.
Such spawn can be sown without problems, you will have blocks with high yield.
But in the illustration below you see not primordia, but whole fungal drusen grown on the surface of the briquette. The photograph shows torn filters that burst under the pressure of growing splices.
To prevent this phenomenon, follow the rules and storage temperature of grain spawn.
If you received it in the same form as in the photo from the transport company, immediately call the manufacturer, send a photo and resolve the issue of replacement.
If you stored the bags incorrectly, try to tear off the sprouts, mash the grains and sow them into bags with a higher dose - 4-5%.
Be sure to label these bags to determine the yield.
But don’t rely too much on the harvest, because the mycelium has wasted a lot of energy on the growth of these bunches and has most likely become inactive.
Bunches of oyster mushrooms can appear not only under filters, but in any place where the cellophane is broken.
If you want to grow some oyster mushrooms to eat, you can try growing these mushrooms on grain. This cute hobby allows you to grow oyster mushrooms on unexpected materials like egg cartons or toilet paper.
You need to buy a package of grain spawn and add it to the grain that you have sterilized.
However, this method is definitely not suitable for growing oyster mushrooms in large quantities.
And I’m not an expert in hobbies.
The grain is not suitable for growing oyster mushroom fruiting bodies for two reasons - firstly, it is too expensive. And secondly, many grains have too much nutrition.
Your substrate may be spoiled because it contains a lot of nitrogen. And there bacteria begin to develop, which, processing nitrogen, release ammonia. Ammonia kills oyster mushroom mycelium.
