How wild fungi adapt to heat and drought, and what growers can learn
Wild fungi live in changing conditions. A hot, dry spell can affect the hidden network of mycelium beneath the soil or inside a log, as well as the mushrooms that appear above ground. Different fungi respond in different ways: some grow in sheltered places, some hold on to water for longer, and some are better suited to dry conditions than others.
For mushroom growers, these adaptations offer useful ideas. They also show why there is no single solution for every crop. The best approach is to understand the needs of your chosen strain, keep an eye on its growing conditions and make careful adjustments when the weather changes.
The hidden life of a fungus
A mushroom is the visible part of a much larger organism. Most of the fungus is made up of mycelium: a fine network of threads called hyphae. It grows through soil, leaf litter or wood, where conditions may be cooler and damper than the air above.
The mushroom, or fruiting body, is more exposed. It can lose water quickly in warm, dry air. A fungus may therefore remain alive in the soil or wood even when the conditions are too dry for it to produce mushrooms.
Fruiting also depends on the species and its surroundings. Some fungi grow with trees, while others break down dead wood or plant material. They do not all respond to heat and drought in the same way.
How wild fungi find and hold on to water
Where a fungus grows can help it cope with dry weather. Leaf litter, shaded ground and decaying wood may hold moisture for longer than open, exposed areas. Some fungi also grow in partnership with trees. Their mycelium connects with the tree’s roots, exchanging nutrients for carbon from the plant. This relationship may help some fungi access water from deeper in the soil, although it does not work the same way for every species.
The mushroom itself may also affect how quickly it dries out. In a study of five mushroom genera, researchers found that the cap’s outer layer helped reduce water loss. How well it did this varied between the fungi studied. You can read the research on fungal cap skins and water loss for more detail.
These are examples of how particular fungi cope in particular settings. A mushroom growing in woodland may benefit from shade, deep soil or a relationship with a tree. A cultivated mushroom growing on a prepared block has different conditions to work with.
Why heat and drought affect fungi differently
Heat can change how a fungus grows, but tolerance varies between species and strains. In laboratory research on oyster mushroom mycelium, heat exposure changed the activity of proteins involved in the fungus’s stress response. The mycelium showed signs of damage during the treatment, then recovered after it was returned to a cooler temperature. A stress response can help an organism cope, but it does not mean the stress has no effect.
Water stress also affects fungi differently. A US Forest Service study of 55 fungal isolates from 18 species found wide differences in how well they continued to grow as water became less available. Some isolates were more tolerant than others, including isolates within the same species.
This variation is a useful reminder for growers. A general description of a mushroom species cannot tell you exactly how every strain will respond to your growing space. The conditions used in research may also differ from those in a home or commercial growing setup.
What growers can learn
Choose a strain suited to your growing conditions
Check the supplier’s guidance for the strain you are growing, particularly its recommended temperatures. The conditions needed for mycelium to colonise a substrate may differ from those needed for mushrooms to form, so follow the instructions for each stage.
A strain described as heat-tolerant still needs suitable growing conditions. Avoid assuming that warmer temperatures will help it grow faster, or that every strain of one species will behave in the same way.
Look at the whole growing environment
Temperature, humidity, substrate moisture and fresh air all matter. They can also affect one another. For example, ventilation brings in fresh air but may also change the temperature and humidity around the crop.
A study of cultivated oyster mushrooms found that high temperature combined with low humidity was associated with lighter, thinner caps and lower fresh weight under the conditions tested. The result applies to that particular growing system, but it illustrates why it helps to monitor more than temperature alone.
When you check conditions, take readings near the crop. The air by a doorway or on the far side of a room may be different from the air around a fruiting block. During a hot spell, pay attention to the substrate as well as the room.
Keep moisture balanced
Too little moisture can restrict growth. Too much can limit air exchange and encourage unwanted organisms. Follow the guidance for your growing system, and avoid treating extra misting as a substitute for managing the wider environment.
The aim is to keep the crop’s conditions steady and suitable for its strain. Wild fungi may have ways of persisting through dry spells, but that does not mean cultivated crops benefit from being put under stress.
Keep simple records
A short growing log can help you understand how a crop responds to your setup. Note the strain, dates, temperature, humidity, watering or misting, ventilation changes and anything you notice about the mushrooms.
If the crop changes during warm weather, these notes can help you spot whether it is a one-off or a recurring pattern. Where possible, adjust one condition at a time. If you change temperature, humidity and airflow together, it is harder to tell which change made a difference.
Plan for seasonal changes
If your growing space becomes warmer in summer, think ahead. Check whether your strain is suitable for the conditions you can provide, consider how you will maintain fresh air, and make sure you can monitor the space during the hottest part of the day. Keep crops away from direct sunlight and heat sources where possible.
Fruiting can also vary with the weather. A delay or change in appearance does not automatically mean a crop has failed. Compare what you see with the strain’s growing guidance and your notes before making a major adjustment.
Wild fungi show how varied the responses to heat and drought can be. Some benefit from sheltered habitats or particular relationships with plants; others tolerate dry conditions better than their neighbours. For growers, the practical lesson is to understand the needs of the strain, monitor the conditions around the crop and make careful adjustments when the weather changes.
Explore Merit Mushrooms’ fresh mushroom range to discover the variety of cultivated mushrooms available.
Comments