Proposed Registration Decision PRD2025-10, Trichoderma asperellum strain T34 and Asperello T34 Biocontrol

Pest Management Regulatory Agency
26 September 2025
ISSN: 1925-0886 (PDF version)
Catalogue number: H113-9/2025-10E-PDF (PDF version)

Summary

Table of contents

• Proposed registration decision for Trichoderma asperellum strain T34
• What does Health Canada consider when making a registration decision?
• What is Trichoderma asperellum strain T34?
• Health considerations
• Environmental considerations
• Value considerations
• Measures to minimize risk
• Next steps
• Other information

Proposed registration decision for Trichoderma asperellum strain T34

Health Canada's Pest Management Regulatory Agency (PMRA), pursuant to subsection 28(1) of the Pest Control Products Act, is proposing registration for the sale and use of T34 Biocontrol Technical and Asperello T34 Biocontrol, belonging to Biocontrol Technologies, S.L., containing the active ingredient Trichoderma asperellum strain T34, a biological fungicide to be used against certain fungal diseases onoutdoor terrestrial food and feed crops (potato, and field grown lettuce, strawberry and raspberry).

Trichoderma asperellum strain T34 is currently registered for use on greenhouse ornamentals, greenhouse vegetables and cannabis produced commercially indoors. For details, see Proposed Registration Decision PRD2011-21, Trichoderma asperellum strain T34; Registration Decision RD2013-19, Trichoderma asperellum strain T34; PRD2020-03, Trichoderma asperellum strain T34, Asperello T34 Biocontrol; and RD2020-07, Trichoderma asperellum strain T34, Asperello T34 Biocontrol.

In addition to outdoor terrestrial food and feed crops, the proposed use pattern of Asperello T34 Biocontrol includes an additional greenhouse crop (tomato), new application methods, and a rate decrease in greenhouse cucurbit vegetables (Crop Group 9) against gummy stem blight.

An evaluation of available scientific information found that, under the approved conditions of use, the health and environmental risks and the value of the pest control products are acceptable.

This summary describes the key points of the evaluation, while the Science evaluation in the full version of Proposed Registration Decision PRD2025-10, Trichoderma asperellum strain T34 and Asperello T34 Biocontrol provides detailed technical information on the human health, environmental and value assessments of Trichoderma asperellum strain T34 and Asperello T34 Biocontrol.

What does Health Canada consider when making a registration decision?

The primary objective of the Pest Control Products Act is to prevent unacceptable risks to individuals and the environment from the use of pest control products. Health or environmental risk is considered acceptable^{Footnote 1} if there is reasonable certainty that no harm to human health, future generations or the environment will result from use or exposure to the product under its proposed conditions of registration. The Act also requires that products have value^{Footnote 2} when used according to the label directions. Conditions of registration may include precautionary measures on the product label to further reduce risk.

To reach its decisions, the PMRA applies modern, rigorous risk-assessment methods and policies. These methods consider the unique characteristics of sensitive subpopulations in humans (for example, children). They also consider the unique characteristics of organisms in the environment. These methods and policies also consider the nature of the effects observed and the uncertainties when predicting the impact of pesticides. For more information on how Health Canada regulates pesticides, the assessment process, and risk-reduction programs, please visit the Pesticides and pest management portion of the Canada.ca website.

Before making a final registration decision on Trichoderma asperellum strain T34 and Asperello T34 Biocontrol, Health Canada's PMRA will consider any written comments received from the public directly related to the proposed decision in this consultation document.^{Footnote 3} Health Canada will then publish a Registration Decision^{Footnote 4} on Trichoderma asperellum strain T34 and Asperello T34 Biocontrol, which will include the decision, the reasons for it, a summary of comments received on the proposed registration decision and Health Canada's response to these comments.

For more details on the information presented in this summary, please refer to the Science evaluation of PRD2025-10.

What is Trichoderma asperellum strain T34?

Trichoderma asperellum strain T34 is a microbial fungicide active ingredient with multiple modes of action against certain fungal diseases on greenhouse ornamentals, greenhouse vegetables, cannabis produced commercially indoors, potato, and field grown lettuce, strawberry, and raspberry.

Health considerations

Can approved uses of Trichoderma asperellum strain T34 affect human health?

Trichoderma asperellum strain T34is unlikely to affect your health when Asperello T34 Biocontrol is used according to the label directions.

The levels used to assess risks are established to protect the most sensitive human population (for example, children and nursing mothers). As such, sex and gender are taken into account in the risk assessment. Only uses that are determined as having no health risks of concern are considered acceptable for registration.

Potential exposure to Trichoderma asperellum strain T34may occur through the diet (food and drinking water) or when handling and applying Asperello T34 Biocontrol. When assessing health risks, several key factors are considered:

• the microorganism's biological properties (for example, production of toxic by-products);
• reports of any adverse incidents;
• its potential to cause disease or toxicity as determined in toxicological studies; and
• the level to which people may be exposed relative to exposures already encountered in nature to other isolates of this microorganism.

Studies in laboratory animals describe potential health effects from large doses of exposure to a microorganism and identify any pathogenicity, infectivity, and toxicity concerns. When Asperello T34 Biocontrol was tested on laboratory animals, the end-use product was of low toxicity by the oral, dermal, inhalation and pulmonary routes of exposure, not irritating to the skin, and minimally irritating to the eye. There were no signs that it caused any disease in treated animals.

All microorganisms, including Trichoderma asperellum strain T34, contain substances that are potential sensitizers and thus, sensitivity may develop in individuals exposed to potentially large quantities of Trichoderma asperellum strain T34.

Residues in food and drinking water

Dietary risks from food and drinking water are acceptable.

Similar to currently approved uses of Asperello T34 Biocontrol on greenhouse food crops, the proposed new uses on terrestrial food and feed crops may result in residues of Trichoderma asperellum strain T34on treated agricultural crops at the time of harvest. However, populations of Trichoderma spp. on crops measured after application are low and decline over time. As well, no secondary metabolites of toxicological significance are detectable in the formulated product or in the edible parts of crops treated with the end-use product. While Trichoderma asperellum and other related Trichoderma species are abundant in nature, no cases involving foodborne illness have been reported. Moreover, there were no signs of infectivity, and low toxicity was observed when Asperello T34 Biocontrol was tested on laboratory animals. In addition, the likelihood of residues of Trichoderma asperellum strain T34contaminating drinking water supplies is expected to be low as the label has the necessary mitigation measures to limit contamination of drinking water from the proposed uses of Asperello T34 Biocontrol. Consequently, health risks from dietary exposure are acceptable for all segments of the population, including infants, children, adults, and seniors.

Occupational risks from handling Asperello T34 Biocontrol

Occupational risks are acceptable when Asperello T34 Biocontrol is used according to label directions, which include protective measures.

Asperello T34 Biocontrol is currently registered as a commercial fungicide for greenhouse food and non-food crops. The new uses include terrestrial food and feed crops. Workers handling Asperello T34 Biocontrol can be exposed to Trichoderma asperellum strain T34through direct skin or eye contact or through inhalation. To protect workers from exposure to Asperello T34 Biocontrol, the label states that workers must wear personal protective equipment, including a long-sleeved shirt, long pants, waterproof gloves, socks and shoes, and a NIOSH-approved particulate filtering facepiece respirator with any N, R or P filter.

The product label includes measures to restrict access to the treated area for four hours or until sprays have dried or dusts have settled. The proposed new uses do not pose any additional occupational exposure concerns.

The health risks to workers are acceptable when the precautionary statements on the label are observed.

Risks in residential and other non-occupational environments

Estimated risk for non-occupational exposure is acceptable.

Asperello T34 Biocontrol is currently registered as a commercial fungicide for greenhouse food and non-food crops. The product label includes measures to prevent bystander exposure such as reducing spray drift. For the general population involved in pick-your-own raspberry and strawberry activities, health risks are not of concern. Residential and non-occupational exposure to Asperello T34 Biocontrol is therefore expected to be low when the label directions are observed. Consequently, the health risk to residents and the general public is acceptable.

Environmental considerations

What happens when Trichoderma asperellum strain T34 is introduced into the environment?

Environmental risks are acceptable.

The proposed use expansion of Trichoderma asperellum strain T34 to include terrestrial food and feed crops is expected to increase environmental exposure to this microorganism. Following application, Trichoderma asperellum strain T34 is likely able to survive in the environment under favourable environmental conditions (i.e., temperature, humidity) but, over time, populations of Trichoderma asperellum strain T34 are expected to return to natural background levels.

No overt adverse effects to birds, non-target terrestrial arthropods (including honey bees), or non-arthropod invertebrates were observed during testing. Toxicity and/or pathogenicity were observed in testing with fish, aquatic arthropods, and non-target aquatic plants; however, these effects occurred at levels that exceed estimated exposure levels when Asperello T34 Biocontrol is used according to the label directions for use. Aquatic exposure is expected to be negligible since the proposed new applications are soil-directed, and the label will include precautionary statements to limit drift, prohibit application to aquatic environments, and reduce runoff to aquatic habitats. Data previously submitted to support the initial registration of Trichoderma asperellum strain T34 were considered to determine that the risk of harm to wild mammals, soil microorganisms, and terrestrial plants is acceptable.

Based on a critical review of studies, scientific rationales and information from public sources, the risks to birds, wild mammals, fish, non-target terrestrial and aquatic arthropods, non-arthropod invertebrates, soil microorganisms, and plants are acceptable when Asperello T34 Biocontrol is applied according to directions on the label.

Value considerations

What is the value of Asperello T34 Biocontrol?

Trichoderma asperellum strain T34 suppresses or partially suppresses listed diseases on greenhouse vegetable crops and ornamentals, cannabis produced commercially indoors, potato, and field grown lettuce, strawberry, and raspberry.

Asperello T34 Biocontrol is a biological fungicide that will provide an alternative disease management product for use on these crops. This product may reduce the risk of resistance to conventional fungicides, as well as provide growers intending to avoid or minimize the use of synthetic pesticides with an additional tool for disease management.

Measures to minimize risk

Labels of registered pesticide products include specific instructions for use. Directions include risk-reduction measures to protect human and environmental health. These directions must be followed by law.

The key risk-reduction measures being proposed on the label of T34 Biocontrol Technical and Asperello T34 Biocontrol to address the potential risks identified in this assessment are as follows.

Key risk-reduction measures - Human health

The existing risk-reduction measures, including personal protective equipment for workers handling Asperello T34 Biocontrol and a 4-hour restricted-entry interval (REI) until sprays have dried or dusts have settled, are sufficient for the proposed expanded uses of Asperello T34 Biocontrol. A standard drift statement is required to mitigate exposure to residents and bystanders.

Key risk-reduction measures - Environment

The end-use product label will include standard environmental precaution statements to prohibit aerial application, limit drift, and reduce runoff and contamination of aquatic systems from the use of Asperello T34 Biocontrol.

Next steps

Before making a final registration decision on Trichoderma asperellum strain T34 and Asperello T34 Biocontrol, Health Canada's PMRA will consider any written comments received from the public that are directly related to this proposed decision, such as comments directed to the science evaluation, in response to this consultation document up to 30 days from the date of publication (26 September 2025) of this document. If more time is required to provide comments, a request for an extension of up to 15 days can be made before the end of the original 30-day consultation period. Please forward all comments to PMRA Publications, through the Public Engagement Portal (Public Engagement Forms – Consultation Comment).

Health Canada will then publish a Registration Decision, which will include its decision, the reasons for it, a summary of comments received on the proposed decision and Health Canada's response to these comments.

Other information

When Health Canada makes its registration decision, it will publish a Registration Decision on Trichoderma asperellum strain T34 and Asperello T34 Biocontrol (based on the Science evaluation section of PRD2025-10). In addition, the test data referenced in this consultation document will be available for public inspection, upon application, in the PMRA's Reading Room. For more information or if you have questions, please contact the Pest Management Information Service.