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Trichoderma biocontrol agents: Types, uses, modes, and their powerful impact 

Theme: Biocontrol agents

Overview

What are Trichoderma biocontrol agents?

Trichoderma biocontrol agents are fungi that can control a wide range of plant pathogens and are one of the most used microbial biocontrol agents. Nearly 200 commercial biopesticide products based on this fungal group are available in the Americas, Europe, Asia, and Africa.

Trichoderma fungi naturally occur in most types of soil, where they play a vital role in the ecosystem’s health. Specific species and strains are particularly efficient at suppressing plant pathogens. These are then isolated and developed into Trichoderma biocontrol products.

As a result, there are around 20 Trichoderma species in the biocontrol market. Among the registered species, there are Trichoderma harzianum, Trichoderma viride, and Trichoderma asperellum.

A microscopic view of hyphae and conidia of the fungus Trichoderma viride
Microscopic view of Trichoderma viride conidia (asexual spores). © CABI

Uses of Trichoderma biocontrol agents

Trichoderma biocontrol agents are effective against many types of pathogens, both soil and foliar.

For instance, Trichoderma can target pathogenic fungi, such as Rhizoctonia, Fusarium, and Verticillium. Trichoderma fungi can also control some oomycetes, such as Pythium and Phytophthora, which cause root rot.

Although Trichoderma species collectively control a wide range of pathogens, certain species might target more effectively specific pathogens. For example, Trichoderma stromaticum can be used against the witches’ broom pathogen, a problematic pest of cacao, notably in Brazilian orchards. This biocontrol agent can be used as part of the Integrated Pest Management of cacao.

In addition to controlling diseases, Trichoderma fungi have positive effects on plants and support healthy crops. They can promote plant growth and improve their resistance against pests and diseases.

You can apply Trichoderma biocontrol agents in several ways, including seed treatment, seedling dip, soil application or foliar spray. Trichoderma fungi can also be used on crops throughout post-harvest storage.

These biocontrol agents come in many forms. Trichoderma products include liquid suspensions that can be mixed with water or sprayed directly. Pellets containing Trichoderma fungi are applied in the soil. Powder is also a common Trichoderma formulation and can be used for dry seed treatment, for instance.

Modes of action of Trichoderma biocontrol agents

Trichoderma fungi can control pathogens in different ways. They can directly affect the pathogen or can help the plant fight the disease.

Direct approach

When Trichoderma fungi are directly fighting one or several pathogens, they have several modes of action. These are:

  • Mycoparasitism: Trichoderma fungi directly parasitize and feed on a pathogenic fungus. This kills or limits the growth of the pathogen.
  • Competition: Trichoderma fungi compete with the pathogen for nutrients and space and actively prevent its access to the plant. As a result, the pathogen starves and gets weaker.
  • Antibiosis: Trichoderma fungi produce secondary metabolites that inhibit the growth of the pathogen, or even kill it.
A microscopic view showing a fungus, Ampelomyces quisqualis, parasitizing another fungus that cause downy mildew
An example of mycoparasitism with Ampelomyces quisqualis, another fungal biocontrol agent, parasitizing downy mildew (Podosphaera aphanis). Credit: Björn S. via Ficklr CC BY-SA 2.0

Indirect approach

In addition to these direct modes of action, Trichoderma fungi have other more subtle, indirect means by which they can aid a crop in combating a pathogen attack.  

Close contact with Trichoderma fungi, either around or within the roots (the rhizosphere) or the aerial tissue, can have a positive effect on crops. This includes:

  • Induction of the plant’s defence system: the presence of Trichoderma fungi triggers the plants to produce specific substances, which make the plant more resistant to harmful organisms. This is like human vaccination and subsequent immune response.
  • Promotion of plant growth and health: Trichoderma fungi produce special substances called metabolites that are absorbed by the plant. This results in increased plant growth and generally better health, making the plant more resilient to stresses and diseases.  
  • Increase in the uptake of nutrients: Trichoderma fungi can break down nutrients in the soil, which become more available to plants. As a result, the general health of the crop improves.

The presence of these indirect effects is dependent on the Trichoderma species or strain used.

Why are Trichoderma biocontrol agents so successful?

The effectiveness of Trichoderma fungi as biocontrol agents comes from several aspects.

  • They are rapid colonizers: they associate and grow on the plant rapidly, which gives them a competitive advantage over pathogens.
  • They have a broad spectrum of pathogens: indeed, a given species of Trichoderma is usually effective against many pathogens, including soil, foliar, and postharvest pathogens.
  • They have multiple modes of action: the diversity of these effects makes it difficult for pathogens to fight back.  
  • They have a positive impact on plant growth. Trichoderma fungi’s effects go beyond disease control. These biocontrol agents induce changes in the plant that make it better able to defend and resist harmful organisms. Thus, the action on pathogens is amplified.

Watch the video below to see the effect of Trianum-P® (CA, EG, ES, FR, GB, HU, KE, MA, PT, US), a Trichoderma biocontrol agent, on the growth of a tomato plant infected by Fusarium.

What are the benefits of Trichoderma biocontrol agents?

Other than being effective biocontrol agents, Trichoderma fungi have other benefits, such as:

  • They reduce the need for chemical pesticides: Trichoderma fungi can prevent or reduce the use of harmful chemicals, which is safer for the environment and human health.
  • They improve soil health: Trichoderma fungi, in addition to increasing nutrient availability in the soil, enable an expansion of the plant’s root system and access to nutrients. This fungal group also improves soil structure.
  • Plant is in better health: Trichoderma fungi improve plant growth, its resistance and tolerance to stresses.
  • They boost crop yields: Trichoderma fungi decompose organic matter, which becomes available to plants through simpler forms. As a result, plants grow better, and crops are more productive.

Trichoderma biocontrol agents in agriculture

Trichoderma fungi can be used for crop protection in a wide range of production systems. Dependent on manufacturers’ recommendations and national registration, it can be effectively used for:

  • Covered crops, greenhouse or polytunnels
  • Field crops
  • Orchard crops
A grower checking on rows of strawberry plants grown under a polytunnel
Strawberries grown in a polytunnel where Trichoderma fungi can be used to control pathogens. © CABI

You can also use Trichoderma biocontrol agents in forestry or in nurseries for seedling production.

For example, Trichonativa® (CL) is a biocontrol agent containing three species of Trichoderma. You can use it on various fruit crops, such as apples, cherries, and pomegranates. It targets many pathogens, including Alternaria spp. And Botrytis spp. The application of the product depends on the pathogen and the crop.  

To maintain product efficacy, always consult and follow the label’s instructions. For more information, read our “How to use bioprotection products” blog.

Want to find out more about Trichoderma and its role in crop protection? 

See how a Trichoderma biocontrol agent has been successfully applied in Spain for lettuce production in the field. 

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