Algae-derived compounds and extracts are increasingly used in agriculture as crop inputs with protective or stimulating effects. Depending on the claimed function and mechanism of action, these products may fall under one of two fundamentally different EU regulatory frameworks: the Fertilising Products Regulation (EU) 2019/1009 EURlex — in particular its biostimulant provisions — or Regulation (EC) No 1107/2009 on plant protection products (PPP) EURlex. The distinction between these two pathways is one of the most practically consequential classification decisions an algae producer can face, because the data requirements, authorisation timelines and market access costs differ by an order of magnitude.

This chapter covers the PPP framework and the biostimulant/biopesticide boundary. The biostimulant pathway under the FPR is discussed in Fertilising Products and Biostimulants.

Under Article 2(1) of Regulation (EC) No 1107/2009, a plant protection product is defined as a product, in the form in which it is supplied to the user, consisting of or containing active substances, safeners or synergists, and intended for one or more of the following uses:

• Protecting plants or plant products against all harmful organisms or preventing the action of such organisms.
• Influencing the life processes of plants in a manner other than as a nutrient (including growth regulation).
• Preserving plant products.
• Destroying or preventing the growth of undesired plants or parts of plants.
• Preventing or inhibiting undesired growth of plants.

The key phrase is the intended use as communicated on the label or in marketing materials. A product marketed as “protecting against fungal disease”, “controlling aphids” or “suppressing weed growth” is a PPP regardless of its biological origin, and must be authorised as such before being placed on the market in the EU.

This boundary is the most practically important and most frequently misunderstood aspect of algae-derived crop inputs. The distinction is not about the substance itself, but about the claimed function:

• A product claimed to enhance nutrient uptake, drought tolerance, quality characteristics or other physiological processes related to plant nutrition efficiency or stress tolerance → biostimulant under the FPR, if it meets the relevant CMC criteria.
• A product claimed to control, suppress or prevent pests, diseases or weeds, or to act directly against a harmful organism → plant protection product under the PPP Regulation, subject to full PPP authorisation.

In practice, many algae extracts — particularly those derived from brown seaweed (e.g. Ascophyllum nodosum extracts) — have both biostimulant effects (growth promotion, stress tolerance) and documented antimicrobial or fungistatic properties. Marketing a product that has antimicrobial activity with any claim referencing that activity — even implicitly, e.g. “reduces disease pressure” — risks triggering the PPP framework.

The European Commission has addressed this boundary in guidance documents, and EFSA has issued opinions on several algae-derived substances. The defining principle is that it is the product as placed on the market, with its specific label claims and use instructions, that is classified — not the substance in the abstract. A manufacturer can sell the same extract as a biostimulant (no pest-control claims, FPR route) or as a biopesticide (explicit pest-control claims, PPP route) — but cannot do both simultaneously for the same product formulation.

Regulation (EC) No 1107/2009 EURlex contains two provisions relevant to algae-derived PPPs that offer a lighter pathway:

• Low-risk active substances (Article 22): substances that pose a low risk to human health, animal health and the environment may be approved with reduced data requirements and faster timelines. To qualify, the substance must be non-toxic, non-mutagenic and not a persistent organic pollutant, among other criteria. Several algae-derived substances could potentially qualify, but approval still requires a full application to EFSA.
• Basic substances (Article 23): substances that are not primarily used as plant protection products but which are useful in plant protection, are not harmful, and are food or feed products, may be approved as basic substances with a simplified procedure. This route has been used for food-grade substances (e.g. lecithin, sucrose) and could in principle be relevant for certain algae-derived materials already authorised as food additives. The procedure is initiated by a member state or applicant and does not require a Notified Body.

The basic substance route is potentially the most accessible pathway for algae producers, particularly for materials already authorised as food additives (e.g. certain algal pigments or polysaccharides), but it requires demonstrating plant protection efficacy and the absence of relevant risk, which is not trivial.

The PPP authorisation system in the EU operates at two levels:

Before any PPP containing an algae-derived active substance can be authorised in any member state, the active substance itself must be approved at EU level. The procedure:

1. Applicant submits a complete dossier (including identity, physical/chemical properties, efficacy data, toxicological studies, ecotoxicological studies, environmental fate and behaviour, residue data in crops, and analytical methods) to a Rapporteur Member State and to EFSA.
2. The Rapporteur Member State prepares a Draft Assessment Report (DAR).
3. EFSA conducts a peer review of the DAR, including a public consultation.
4. EFSA issues a conclusion on the active substance.
5. The European Commission adopts an implementing regulation approving or not approving the active substance, with specified conditions of use.

This process takes a minimum of 3–5 years and costs several million euros in study generation and application fees for conventional chemistry. For biological substances (including algae-derived materials), data requirements may be somewhat reduced — particularly for toxicological endpoints where a long history of safe use can substitute for some animal studies — but the fundamental structure of the dossier remains the same.

Once the active substance is approved, the formulated PPP must be authorised in each member state where it will be sold. Member states evaluate:

• The efficacy of the product under local agricultural conditions.
• The safety of the formulated product (including co-formulants and adjuvants).
• Compliance with maximum residue levels (MRLs) for crops where applicable.

EU zones (North, Central, South) allow for mutual recognition of authorisations, but market access still requires at least one national authorisation per zone. For biological PPPs, this zonal system can simplify market rollout, but the fundamental member-state-by-member-state character of the authorisation landscape remains.

The following application areas are relevant to algae-derived PPPs:

Certain algae extracts — notably polysaccharide-rich fractions from brown seaweed — stimulate the plant's own defence mechanisms (Systemic Acquired Resistance, SAR, or Induced Systemic Resistance, ISR) without directly killing the pathogen. This mode of action — acting on the plant rather than on the pest — is a grey area in the classification debate. Commission and EFSA guidance has generally treated products with documented SAR/ISR effects and associated disease suppression claims as PPPs rather than biostimulants, but the boundary remains contested and is subject to ongoing regulatory clarification.

Several algae-derived compounds have demonstrated direct toxicity to pests or pathogens:

• Fucoidan and laminarin (brown seaweed polysaccharides) have demonstrated antifungal and antibacterial activity in laboratory and field trials.
• Certain phycotoxins (such as okadaic acid derivatives) have pesticidal properties, though their use as PPPs is unlikely given toxicity concerns for non-target species.
• Microalgae-derived compounds (fatty acids, phenolics) have demonstrated insecticidal and herbicidal activity in research settings.

None of these have completed EU active substance approval as PPPs as of the date of this review, but several are in the pre-registration pipeline or have been subject to EFSA assessments.

Living algae and cyanobacteria have been used as biocontrol agents — for example, cyanobacteria producing natural herbicidal compounds in rice paddies, or microalgae competing with phytopathogens for resources. The regulatory classification of living organisms as PPPs is complex and requires assessment of both the organism and any produced metabolites.

• Fertilising Products Regulation (FPR): Products with biostimulant claims only — and no pest-control claims — may qualify for the FPR biostimulant route, with substantially lower data requirements and no centralised active-substance approval needed. See Fertilising Products and Biostimulants.
• REACH: Algae-derived active substances placed on the market as PPPs are chemical substances under REACH. However, active substances approved under the PPP Regulation benefit from a specific exemption from the REACH registration obligation under Article 15 of REACH.
• Organic farming: Some biopesticides and biocontrol agents are compatible with organic farming rules (Regulation (EU) 2018/848). For a PPP to be usable in organic farming, it must appear on the list of permitted substances in Annex II to the organic regulation. Algae-derived products authorised as PPPs may be eligible for inclusion if they meet the organic criteria.

• Decide on claims before product development: the biostimulant/biopesticide classification decision should be made before significant investment in product formulation, because it determines the entire regulatory strategy. A product with demonstrable pesticidal activity that is marketed with biostimulant claims only remains a regulatory risk — national authorities can reclassify it as an unauthorised PPP if the underlying activity is identified.
• Explore the basic substance route for food-grade materials: for algal materials already on the food market, the basic substance procedure under Article 23 of Regulation (EC) No 1107/2009 may offer a lower-cost route to plant protection use. This is underused by the algae sector.
• Document mode of action carefully: regulatory outcome depends heavily on the documented mechanism of action. Producers developing algae-derived crop inputs should invest in scientific studies that clearly characterise whether the effect is on plant physiology (biostimulant) or on the pest/pathogen (biopesticide), because regulators will require this evidence in either case.
• Budget realistically for PPP authorisation: the full PPP pathway — active substance approval plus national product authorisations — typically requires 5–10 years and €3–8M in direct costs (studies, application fees, regulatory affairs). This is a scale of investment that requires either a consortium approach or a licensing partnership with an established crop protection company.
• Monitor the regulatory evolution: the EU is actively working on measures to facilitate biopesticide authorisation, including faster timelines for biological active substances and better mutual recognition. The regulatory environment for algae-derived PPPs is improving, but slowly.

See also: Fertilising Products and Biostimulants | REACH and Chemicals Regulation | Organic Production and Certifications | Purpose, Scope and Sources

Last reviewed: September 2026.