Emma Wilson
Mushrooms are a fun and rewarding crop to grow, but they are susceptible to contamination. Contamination is the presence of unwanted organisms or microorganisms that interfere with mushroom growth and can cause long-term problems or crop failure. The most common contaminants are bacteria, mould, and pests. To avoid contamination, it is essential to maintain proper sanitation and use sterile substrates and equipment. This includes sterilizing your growing medium and tools, as well as practising good personal hygiene, such as washing your hands and wearing clean clothes. Additionally, controlling the temperature and humidity of your growing environment can help prevent mould growth. Even with these precautions, contamination may still occur, but by implementing these practices, you can reduce the chances of it affecting your mushroom crop.
How to Avoid Mushroom Contamination
| Characteristics | Values |
|---|---|
| Growing Environment | Avoid open-air growing, use a grow tub that is mostly closed |
| Sanitation | Wash hands, wear gloves, a face mask, and clean clothes |
| Sterilization | Use a laminar flow hood, a still air box, or a pressure sterilizer |
| Substrate | Keep substrate at or below field capacity (68% hydration), use pasteurization or sterilization to prevent unwanted microbes |
| Equipment | Use a clean knife, scissors, or cutting implement |
| Storage | Do not store the kit for too long, avoid growing in warm and humid weather |
Explore related products
What You'll Learn
Sterilise equipment and growing environment
The equipment and growing environment must be thoroughly sterilised to prevent contamination and ensure successful mushroom growth. This is especially important for high-nutrient substrates, which are more prone to contamination by bacteria and mould.
Pressure Cooker
A pressure cooker is a common method for sterilising mushroom substrates, as it can achieve the required temperature and pressure for sterilisation. Small-scale growers can use a pressure cooker that maintains a pressure of 15 PSI. Before using a pressure cooker, it is crucial to inspect it for any damage, such as dents, bulges, or cracks, and ensure that all components, including seals and screws, are in good working order.
Alternative Methods
For those without access to a pressure cooker, other methods can be employed to sterilise equipment and substrates. One option is to use a steam steriliser, which can be purchased or, in the case of barrel steam sterilisers, built at home. While these may not reach the same temperatures as a pressure cooker, they can still achieve temperatures close to sterilisation levels. Additionally, a microwave can be utilised for sterilisation, although only small batches can be processed at a time.
Pasteurisation
While pasteurisation does not achieve complete sterilisation, it is a suitable method for low-nutrient substrates. Pasteurisation involves maintaining a temperature of around 70°C (158°F), which is sufficient to reduce the number of competing organisms. This method may require a longer processing time and can be achieved through a DIY approach to building the necessary equipment.
Post-Sterilisation
After sterilisation, it is essential to allow the substrate to cool for at least eight hours before inoculation. Maintaining aseptic conditions during this stage is crucial to prevent contamination by other organisms.
Mushroom Magic: Spores and Their Names
You may want to see also
Maintain hygiene and sanitation
Maintaining hygiene and sanitation is key to avoiding contamination when growing mushrooms. The human body is the greatest source of contamination in mushroom cultivation. Human hands and clothes carry countless bacteria and spores that can ruin crops. Therefore, it is important to take a shower, wash your hair, and use hand sanitiser before handling mushrooms. Wearing clean clothes, such as a lab coat or scrubs, is also recommended. Additionally, consider using laboratory gloves and a face mask or mouth covering to avoid breathing or speaking near the mushrooms, as this can introduce contaminants.
To ensure a sanitary environment, it is crucial to understand where contamination may originate. Mushrooms are susceptible to bacteria, moulds, and animal pests. Discolouration, such as yellow or brown spots or streaks, is one of the most obvious signs of contamination. It is also important to maintain a clean and sanitised growing space. Use a laminar flow hood, which includes a filter pad, fan, and High Efficiency Particulates Air (HEPA) filter, to reduce airborne contamination. If a flow hood is not feasible, a more affordable option is a still air box, which is effective for small-scale projects.
Proper sanitation extends to the tools and equipment used in mushroom cultivation. Isopropyl alcohol, commonly found in pharmacies, can be used for cleaning and sanitation. Additionally, pasteurisation and sterilisation are essential to treat mushroom substrates and eliminate microscopic competition from unwanted microbes. Sterilisation can be achieved using pressure sterilisers, ensuring that only the desired fungi have the opportunity to grow.
To prevent the spread of contamination, it is crucial to act quickly. If contamination is detected, isolate the affected area and dispose of any contaminated substrates, grains, or tools. Seal the contaminated material in a plastic bag and sanitise the affected area and surrounding workspace. Regular monitoring of the growing operation is essential to identify signs of contamination early on and prevent widespread crop failure.
Oyster Mushrooms: Sunlight or Shade?
You may want to see also
Prevent over-hydration
Water is essential for mushroom growth, but it's easy to overdo it, which can lead to poor yields, crop failure, or mould. Mushrooms prefer a substrate that is about 60-70% water. This means that for every 100 grams of substrate, you should add 60-70 grams of water.
To prevent over-hydration, it's important to monitor the moisture content in both the air and the substrate. Humidity sensors, such as those offered by NiuBoL, allow growers to continuously monitor moisture content, ensuring it remains within the optimal range for mushroom growth. Regularly check sensor readings and adjust humidity levels as needed, based on the type of mushrooms being cultivated. Record data to track environmental conditions over time. Consistent monitoring and timely adjustments to humidity levels are key to preventing common cultivation issues such as excessive moisture.
Additionally, maintaining a consistent level of humidity is crucial. Fluctuations in moisture levels can stress the mycelium, impacting the overall health and yield of the crop. Cultivators can establish a routine that includes regular misting and monitoring to ensure their mushrooms thrive.
To gauge the hydration level of the substrate, you can use the "squeeze test." Take a small amount of substrate in your hand and give it a gentle squeeze. If water droplets appear on the surface, the substrate is likely too wet. The substrate should be kept at or below field capacity (68% hydration).
Finally, it's important to avoid overwatering by ensuring the mushroom kit is not located in an enclosed space or in direct sunlight. Avoid placing it near heat sources, such as radiators, cupboards, or cabinets. Keep the topsoil damp, especially the edges, as they tend to dry out faster.
Reconstituting Shiitake Mushrooms: A Quick Guide
You may want to see also
Explore related products
Use a laminar flow hood
A laminar flow hood is an effective way to prevent contamination when growing mushrooms. It creates a clean, sterile environment by blowing air through a High-Efficiency Particulate Air (HEPA) filter, which captures contaminants such as dust, spores, and bacteria. This filtered air moves in parallel lines across the work surface, pushing potential mushroom contaminants away and creating a sterile workspace.
The laminar flow hood provides a consistent flow of clean air over a workbench, allowing cultivators to perform tasks such as inoculation without introducing airborne contaminants. The ideal air velocity for a laminar flow hood is 100 feet per minute or 0.5 meters per second. It is important to maintain this speed as too fast or too slow will cause turbulence, reducing the sterile area.
There are two main types of laminar flow hoods: horizontal and vertical airflow. Horizontal hoods are more common for mycology work due to their large surface area and airflow design, which protects the work area from contamination. Vertical hoods, on the other hand, blow air vertically downward from above the cultivator. The choice between the two depends on specific project requirements, available workspace, and personal preference.
When building a laminar flow hood, it is important to use a specific type of HEPA filter. An H13 or H14-rated filter is recommended as it removes more than 99.97% of particles at 0.3 microns in diameter. Additionally, the filter should be replaced every 5-10 years, depending on usage. The rest of the construction can be made from materials such as stainless steel or plastic polymers.
Laminar flow hoods can be purchased pre-built or DIY kits are available for those who want to build their own. While they may be expensive, they are a worthwhile investment for those serious about mushroom cultivation, significantly reducing the chances of contamination and ensuring consistent yields.
Button Mushrooms: Cancer Causers or Not?
You may want to see also
Choose the right substrate
Choosing the right substrate is crucial for successful mushroom cultivation, akin to how different plants prefer specific types of soil and growing conditions. Mushrooms derive their nutrients from the substrate, so it is important to select one that suits your chosen mushroom variety.
There are various types of substrates available, and some common ones include manure, compost, sawdust, straw, wood chips, hardwood dowels, logs, leaf litter, and cardboard. Logs are a popular choice for mushroom cultivation, as they mimic the natural conditions in which mushrooms grow, often resulting in tastier and higher-quality fungi. However, it is important to note that freshly cut logs should be avoided, as trees possess natural fungi-preventing properties while they are alive. Instead, it is recommended to store freshly cut logs in a clean and dry environment for a few months before inoculating them with mushroom spawn.
When selecting a substrate, it is essential to consider the nutritional content and the potential for contamination. Mushrooms are susceptible to bacteria and mould, which can develop faster than mushroom mycelium, hindering their growth. Therefore, it is crucial to choose a substrate that can be effectively pasteurized or sterilized to reduce the risk of contamination.
Some substrates, such as soybean hulls, can be dense and hold excessive moisture, creating low-oxygen conditions that slow down mycelial growth or lead to contamination. In such cases, it is important to carefully monitor and adjust moisture levels and employ proper sterilization methods to mitigate contamination risks.
Additionally, certain mushroom varieties may require specific substrates. For example, Wine Cap mushrooms thrive in outdoor beds composed of Wood Lovr and straw, while CVG (Coco Vermiculite Gypsum) is a beginner-friendly substrate blend that is lightweight, contamination-resistant, and suitable for small-scale indoor cultivation.
Harvesting Mushrooms: When to Pick Minotub Varieties
You may want to see also
Frequently asked questions
Mushroom contamination refers to the presence of unwanted organisms or microorganisms that interfere with mushroom growth and cause long-term problems or crop failure.
Contamination can come from bacteria, moulds, and animal pests. The human body is also a significant source of contamination, as human hands and clothes can carry bacteria and spores that can ruin crops.
To prevent contamination, it is essential to maintain proper sanitation, use quality spawn and substrate materials, and implement pest management strategies. Sterilization of equipment and substrates is crucial, and it is also important to control the concentration of airborne particles in the growing environment.
Discolouration is one of the most obvious signs of contamination. For example, the presence of yellow or brown spots or streaks on the surface of mushrooms or the growing medium. Contamination by Trichoderma, a common type of mould, can be identified by its fluffy appearance rising from the substrate.
![McKesson Cotton Tipped Applicator, 6 in [100 Count] Long Sterile Medical Swabs, Individually Wrapped, Wood Shaft](https://m.media-amazon.com/images/I/61y4nxRNd2L._AC_UY218_.jpg)
