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Is There Toxigenic Mould in Wood Chip Mulch?

Toxigenic mould in wood chip mulch can be a serious concern for homeowners and gardeners. Mould is a type of fungi that can grow on various surfaces, including wood, and it can produce toxins that can be harmful to humans and animals. In this article, we will discuss what toxigenic mould is, how it can affect wood chip mulch, and what you can do to prevent it from growing.

What is Toxigenic Mould?

Toxigenic mould, also known as toxic mould, is a type of mould that produces toxins known as mycotoxins. These toxins can be harmful to humans and animals if they are inhaled or ingested. Some common types of toxigenic mould include Aspergillus, Stachybotrys, and Fusarium.

Toxigenic mould can grow in a variety of environments, including damp or humid areas. It can also grow on a wide range of materials, including wood, paper, and textiles. In the case of wood chip mulch, the mould can grow on the surface of the mulch or within the layers of the wood chips themselves.

How Does Toxigenic Mould Affect Wood Chip Mulch?

Toxigenic mould can grow on wood chip mulch if the conditions are right. The mould needs moisture, a food source, and a warm environment to thrive. Wood chip mulch can provide all of these conditions if it is not properly maintained.

If toxigenic mould grows on wood chip mulch, it can produce toxins that can be harmful to humans and animals. These toxins can be inhaled or ingested, and they can cause a range of health problems, including respiratory issues, allergies, and even cancer.

In addition to the health risks, toxigenic mould can also affect the appearance of wood chip mulch. The mould can cause the mulch to change color and become discolored or spotted. It can also produce a musty or unpleasant smell.

What Sort of Toxigenic Mould is Found in Wood Chip Mulch?

In a study looking at the mycoflora of wood chips to be used as mulch, a total of 114 types of fungi were identified from 2500 wood chips(Hoover-Litty and Hanlin, 1985). There were 82 genera and, out of them, Trichoderma, Fusarium, Chaetomium, Aspergillus, Rhizopus and Graphium accounted for 48.6% of the isolates were pathogenic (Hoover-Litty and Hanlin, 1985). None of the other species occurred in more than 5% of the samples (Hoover-Litty and Hanlin, 1985). Wood chips, bark mulches and composts can also contain other types of fungi such as slime molds, bird’s nest fungi, stinkhorns and mushrooms (University of Massachusetts Amherst, 2011). Under healthy aerobic soil conditions, the harmless fungi probably outcompete the pathogenic fungi.

Preventing Toxigenic Mould in Wood Chip Mulch

There are several steps you can take to prevent toxigenic mould from growing in your wood chip mulch. Here are a few tips:

  1. Keep the mulch dry: One of the most important things you can do to prevent toxigenic mould is to keep your wood chip mulch dry. This means avoiding overwatering your plants and keeping the mulch away from areas that may be prone to standing water.
  2. Add fresh mulch regularly: Over time, wood chip mulch can break down and become compacted. This can create a warm and moist environment that is ideal for mould growth. To prevent this, it is a good idea to add a fresh layer of mulch to your garden regularly.
  3. Avoid using mulch that is already mouldy: If you are purchasing wood chip mulch from a store or supplier, be sure to inspect it carefully before using it. Avoid using mulch that appears to be mouldy or has an unpleasant smell.
  4. Properly store mulch: If you have leftover mulch, be sure to store it in a dry place. Do not leave it outside where it may become wet and create a breeding ground for mould.
  5. Remove and dispose of mouldy mulch: If you notice that your wood chip mulch has become mouldy, it is important to remove and dispose of it as soon as possible. This will prevent the mould from spreading and will protect your health and the health of your plants.


Toxigenic mould in wood chip mulch can be a serious concern for homeowners and gardeners