Given the ambitious targets set in the Farm to Fork strategy to reduce fertiliser inputs by 20% and pesticide inputs by 50% by 2030 as part of the EU Green Deal, there is currently a big push towards “bio” products as sustainable alternatives for crop production.

Plant biostimulants, biofertilisers and biopesticides are terms discussed as alternative inputs for sustainable crop production but what do these terms mean, and what do these products do?

The different terms (biostimulants, biofertilisers and biopesticides) are confusing, partly because they are largely new concepts and products that fit into the different categories were only recently defined in any kind of legislation.

In 2019, the EU introduced the unifying EU Fertilising Products Regulation for fertilising products, which includes plant biostimulants (regulation (EU) 2019/1009).Under this regulation, plant biostimulants are “substances and micro-organisms which can stimulate natural processes to improve nutrient uptake, nutrient efficiency and crop quality”.

Products often described as biofertilisers also fall under the EU Fertilising Product Regulation, although the term is in fact not used in these regulations which refers to “organic fertilisers” and “soil improvers”. The ingredients of biostimulants and such fertilisers are found under the component material categories of the EU fertilising products.

This overlap in terms and the interchangeable use of biofertilsers and biostimulants has led to considerable confusion regarding the different types of products available.


The European Biostimulants Industry Council (EBIC) explains that the aim of biostimulants is to “ensure that plants have good baseline strength and health, making plants less vulnerable to stress, pests, and other threats, including climate shocks”.

This is a fairly broad definition and many different products fall under this category.

In July 2022, the first CE-marked fertilising products will be available on the market where any claims on the label of these products will need to have been justified by evidence.

Some examples of common plant biostimulants include mycorrhizal fungi and endophytes.

Mycorrhizal fungal inoculum

This type of product contains live fungal spores and other propagules of arbuscular mycorrhizal fungi (AMF) which, when applied to soil, form beneficial associations with plant roots and help them gain access to minerals, especially phosphorus.

There is some evidence that the effect of mycorrhizal fungi on plants extends beyond nutrient gain and that they can also protect crop plants such as wheat, barley and maize from stress, including drought, salinity and disease.

For example, AMF has contributed to the protection of wheat against powdery mildew and root rot caused by fusarium under controlled conditions.

AMF also protected barley plants from take-all disease under controlled conditions.

In terms of nutrient use efficiency, mycorrhizal inoculum can benefit the growth and yield of wheat.

However, this benefit was best seen under low or reduced nutrient input, or under drought stress.

Therefore, the benefit of mycorrhizal inoculum is best achieved under reduced fertiliser application, or under stressful abiotic conditions.

Many products are applied with a sprayer.

Another factor to consider is that although mycorrhizal fungi tend to be quite generalist, ie able to form associations with different plant species, certain mycorrhizal fungi are species-specific.

This makes a difference when choosing between different mycorrhizal inoculum products and so it is always advisable to check the specifications from the manufacturer.


These can be bacteria or fungi which live inside plant tissues (leaves, shoots, roots) but do not cause any disease symptoms.

Beneficial endophytes have been shown to help with yield in barley field trials.

Positive impacts on seedling establishment, nutrient uptake, drought stress and reducing disease susceptibility to fusarium head blight have all been reported under controlled conditions.

UCD and Trinity College Dublin have been working together on this for about eight years to identify beneficial endophytes from wild crop relatives and this recently led to the formation of a spinout company. The fungal endophytes can be applied through seed coatings and research at UCD/Trinity College Dublin is ongoing to discover new beneficial endophytes, as well as combinations of endophytes which could work together to improve plant health.

A mix of microorganisms

Biostimulants can also be a mix of microorganisms. A few years ago, a PhD student (T. Twamley) studied a microbial fermentation product which contains bacteria and yeast from fermentation brewing media.

Spraying wheat with this fermentation product reduced powdery mildew and fusarium head blight (FHB) disease in wheat, but unfortunately it did not significantly decrease septoria tritici blotch (STB).

The reduced disease was partly due to the product switching on defence genes as the plant can detect the presence of bacteria and yeast as part of an immune response. This works a bit like vaccination in animals. This biostimulant also improved grain weight in wheat, even without any disease being present.

At the moment, we are trying to understand what happens when different microorganisms are used or mixed together to see if different sets of defence genes are switched on. This might help in designing products in the future. But, ultimately, we will need to test this in the field.


A very common plant-based biostimulant ingredient is seaweed. Seaweed (Ascophyllum nodosum) contains biomolecules which are extracted and can be converted to shorter bioactive compounds. Such seaweed extracts have been shown to increase plant productivity and crop yield (up to 18% in potatoes) in the field.

Trials using a reduced nitrogen rate of 75% and a seaweed biostimulant increased nutrient use efficiency while maintaining barley yields. Other seaweed products can decrease pod shatter and yield loss in oilseed rape.


This term covers a wide spectrum of products used as plant protection products (PPP) and these fall under the plant protection regulation (EC) No 1107/2009. This regulation lays down rules for the sale, use and approval of any plant protection product in the EU, including conventional synthetic pesticides and biopesticides.

Biopesticides are based on microorganisms or natural products such as chemicals (eg pheromones), natural substances (eg botanicals, biochemicals) and microbials (eg bacteria, fungi, nematodes and viruses).

Trials on UCD Lyons Farm as part of the Bio Crop project. \ Mariluz del Pino-de Elias

The activity and functioning of biopesticides is now being widely researched. For example, at UCD, we are identifying extracts from fungal endophytes that can directly inhibit the growth of ramularia, while at NUI Galway work is ongoing to identify algal extracts that can inhibit growth of the same fungus.

Ultimately, biopesticides are active substances that can reduce the incidence of crop disease and could be used in place of chemical pesticides. In the EU, biopesticides face the same evidence and approval criteria as synthetic pesticides and this can be a barrier to market.

Live microorganisms

With regard to live microorganisms as plant protection products, these rules are expected to be amended this year.

The main aim is to allow better access to sustainable alternatives to chemical pesticides across the EU

The new rules will take account of the latest scientific evidence and help speed up the approval and authorisation of microorganisms for use as active substances in plant protection products. The main aim is to allow better access to sustainable alternatives to chemical pesticides across the EU, which can also be used in organic agriculture.

Evaluation of efficacy remains essential

As part of a Department of Agriculture, Food and the Marine-funded project called “BioCrop”, we are testing available biostimulants while developing new biostimulants and biopesticides.

The project will also look at the cost of these and perform a lifecycle sustainability assessment.

This project is a collaboration between UCD, Teagasc, Trinity College Dublin, NUI Galway and partners including Brandon Bioscience, NovaQ, CropBiome, Glanbia and the University of Seville.

The field trials are assessing three different products in barley trials at UCD Lyons Farm to see if they can be used to further reduce fertiliser applications without compromising yield and for any positive impact on plant health.

Endophyte seed coatings are also being trialled by Teagasc at Oak Park and assessed for yield and quality.

These will also be assessed for any impact on disease incidence, including their impact on ramularia leaf spot and barley yellow dwarf virus.

Over the last few years, the number of studies showing that biostimulants and biopesticides can improve nutrient use efficiency, yield, stress and crop health issues have increased. These have predominantly been tested with horticultural crops but evidence for their use and effectiveness in tillage field crops lags behind.

Researchers on the project

  • UCD – Angela Feechan, Saoirse Tracy, Rainer Melzer, Fiona Doohan, Grace Cott, Carl Ng, Paul McCabe, Michael Wallace, Fionnuala Murphy.
  • Teagasc – Steven Kildea, Louise McNamara, Fiona Thorne.
  • Trinity College Dublin - Trevor Hodkinso.
  • NUI Galway - Zoe Popper.
  • Comment

    Field trials are needed, such as those conducted as part of “BioCrop” over the next few years, to determine if these products can contribute to reducing conventional inputs for crop production. Such trials need to test the broad range of different ingredients to determine if these products can contribute to reducing conventional inputs for crop production.

    With the powers that be aiming to ease the burden of evaluation to free up availability of such products, it is essential that they are proven to work in the markets in which they are targeted.

    To not insist on this basic requirement of any purchased product would be to set back their acceptance as alternative or complementary solutions to the production of field crops.

    The CE-marked fertilising products from July 2022 will help to certify this.

    There is also a need to ensure that any of these products have no unintended consequences in terms of food safety and environmental health, characteristics which are at the centre of the evaluation of synthetic pesticides. Just because something is naturally occurring does not mean it is universally safe and the converse is true of synthetic products.

    The EU Plant Protection Regulation will help to ensure the safety of these products.

    However, the development of these growth-enhancing alternatives in combination with an ability to harness different elements of nature to help protect our crops and food must be advantageous in the longer term.

    It is possible that this type of basic research will help identify improved natural control systems which take place in a healthy soil. This might be harnessed by soil husbandry and rotational management to help do these things naturally without any or little purchased interventions.

    Key points

  • The Farm to Fork strategy aims to reduce pesticide use by 50% in the EU.
  • Plant biostimulants, biofertilisers and biopesticides, are terms suggested as alternative inputs for sustainable crop production.
  • The interchangeable use of biofertilsers and biostimulants has led to considerable confusion regarding the different types of products available.
  • BioCrop is a new project which is testing biostimulants and biopesticides in the lab and the field.
  • Some of these products have been shown to prevent disease and help to improve nutrient use efficiency.