Fungi large and small, enemies and allies, are a part of our everyday lives. They are particularly common in some gardens. In fact, overly humid or wet gardens have a greater tendency to have fungal problems. This is because fungi prefer low light and wet, undisturbed conditions.

Many fungi reproduce by releasing spores, which are tiny groups of cells that float through the air in the hopes of landing in a hospitable area to form a new colony. Spores from common local fungi are often already present in gardens and are just awaiting proper conditions to begin growth.

Continuous available moisture encourages spore growth, and humidity above 70% is ideal for fungal growth (although outbreaks can occur at lower levels). Air circulation can also have a strong influence on fugal growth, since poor air movement can create pockets of high-humidity air around plant material.

Since fungi do not use chlorophyll, they have few light requirements (hence why they often prefer darker areas). Fungal outbreaks can start in as little as 24 hours of appropriate conditions.

When it comes to fungi in the garden, prevention is easier than treatment. So, keeping humidity under control, removing decomposing plant material and the elimination of standing water are the best methods to avoid an initial outbreak.

If a colony becomes established, it must be treated in most cases for the plant to survive. Correction of environmental issues, removal of colonized plant material, chemical fungicides and biological fungicides are all options for treatment.

Here is a list of some of the more common fungi found in gardens (and some specific ways to avoid them):

  • Stem rot is a fungus that can develop on, and kill off, overwatered seedlings. Once contracted, it is usually fatal, but can be avoided in the first place by proper watering.
  • Root rot is also caused by overwatering plants, but again can usually be avoided with proper watering and root aeration.
  • Gray mold attacks areas of poor air circulation and can usually be avoided with some combination of proper ventilation, trimming areas of dense growth and trying the plant open to allow for internal airflow.
  • Powdery mildew is another moist garden fungal menace, common to appear, but with several treatment options including milk and other homemade remedies.
  • Verticillium wilt is a destructive fungus that invades and grows inside infected plants, an almost always fatal and untreatable arrangement.
  • Dutch elm disease is another terminal fungal ailment.

On the more friendly fungal side, yeast is a fungus commonly used to make bread rise and create the alcohol in wine and beer. Edible mushrooms can be grown at home using logs inoculated with the proper mushroom spores (some mushrooms can be toxic, so make sure of the identity of any mushroom considered for consumption).

Fungi also help out in the garden. They assist in plant decomposition and the conversion of waste plant material into compost by breaking down large and woody plant material into forms more accessible to further decomposition by bacteria. Mycorrhizal fungi have also formed symbiotic relationships with plants.

Mycorrhizae are found naturally occurring in healthy “live” soil, where they eat the carbohydrates provided by the plants and, in return, assist the plant in drought resistance, blocking their environmental niche from pathogenic fungi and nutrient uptake. Of particular use is their ability to increase phosphorus uptake, which dramatically increases over non-infected plants.

In the end, there are good fungi and there are some unpleasant ones. Like with everything else, make friends with the good and avoid the bad where you can.