Biostimulants – choosing a star performer

Biostimulants could be the missing link that help growers overcome some of the issues experienced in peat free growing. But with many different biostimulant products on the market, it’s important to choose the right one for your crop.

When I say that watching this summer’s Olympic Games Paris 2024 made me think of biostimulants you may think I’ve gone more bonkers than its opening ceremony. But – hear me out.

I’m sure you’ll agree that the Olympics’ huge range of different categories – from swimming to American soccer – means that even the most non-sporty of people can find at least one event in the Games that they enjoy spectating. The quadrennial event is also a reminder of the wide range of sports that are out there for us to try. (Note to self – I really must sign up to a triathlon, once and for all!)

And just as there’s arguably a sporting activity that’s suited to each of us, there’s a biostimulant that’s right for your crop.

But before we race ahead of ourselves, what, exactly, are biostimulants?

Sam Rivers, ICL’s Technical Manager for Controls, explained during this summer’s Hort Science Live event (not quite the Olympics, but an epic event nevertheless) that biostimulants are products that when applied to plants or their rhizosphere. Stimulate natural processes which  can benefit the plants’ nutrient uptake, nutrient efficiency, tolerance to abiotic stress and crop quality – independent of their nutrient content.

Biostimulants can be based on a wide range of substances, including microorganisms such as beneficial bacteria (eg. Bacillus subtilis) and beneficial fungi (eg. Mycorrhizal fungi). They’re also commonly-based on seaweeds (eg. Ascophyllum nodosum) and there are yeast-based products (eg. Saccharomyces cerevisiae) available too. Also on the market are biostimulants based on humic substances (eg. humic acid), metabolites (including amino acids), and inorganic substances such as silicon.

Choosing a star performer

Basically, biostimulants help the plants to become fighting fit “athletes” in the competitive business of growing. What they are not, however, is a replacement for precise, targeted (controlled/slow release) nutrition and robust IPM practices, asserted Sam. He also noted that it’s important to understand that not all biostimulants are the same. “There are thousands of different products out there. And I do think they sometimes get grouped into one category – so it’s important to understand the differing effects they each have on plant growth.”

Given that UK growers are rapidly switching to peat-free growing, Sam is busily investigating how biostimulants can be used to overcome some of the issues growers are experiencing during this transition. He said: “Generally speaking, there are numerous benefits to using plant microbes. For example, they are extremely beneficial to soil productivity – they can help break down plant residues and improve soil carbon and pH. When we talk about peat free growing media we look at the raw materials and how they’re processed. Woodfibre is super-heated, coir is steam-sterilised – we see that the growing media becomes quite sterile.”

“But in media like bark, we see that they are among the most biologically-active products on the market. In fact, The Forestry Commission published a study looking at this and actually found that bark has a really high number of phytopathogens such as phytophthora and pythiums. This doesn’t necessarily mean that you are seeing them from a growth perspective – it’s just that the likelihood might increase if you have the perfect conditions for their growth. So, we have to really understand how the different growing media mixes  being used might have different microbial content – and a lot of research you see on this is actually done in soils. But when we talk about containerised nursery stock it’s a fairly different picture.”

Going for gold

This is where Vitalnova TriBoost (now available in a 5kg pack) is sprinting ahead of its competitors. Part of ICL Ornamental Horticulture’s Vitalnova range, it consists of three live microbial strains that – following extensive research – have been specially selected to optimise the soil microbiome, improve soil structure, and bolster root development and plant vigour.

Sam explains: “Bacillus subtilis helps with the fixation of nitrogen, and increases the availability of phosphorus, potassium, and zinc. Enterococcus faecium has been researched to positively influence and induce plant growth hormones such as gibberellins, and then Lactobacillus shows improvement in overall plant health.”

Also sprinting out of the blocks is Vitalnova Prime, which is derived from the yeast Saccharomyces cerevisiae. Yeast cell walls are rich in amino acids and peptides which are known to act as natural elicitors within the plant – stimulating natural processes and improving plant quality traits.

A new version of Vitalnova Prime will soon be available and registered under the EU’s Fertiliser Product Regulations (FPR). In the spirit of good sportsmanship, biostimulants must now be FPR registered. To meet these new EU requirements, the products must be extensively and independently trialled. The UK is fast behind the EU and is expected to finalise its own stringent regulatory approach in the near future.

ICL’s biostimulant products are therefore undergoing further trials to meet the requirements for this new legislation. “We’re futureproofing the use of these products in ornamentals,” said Sam. “Going forward, this gives you [growers] a lot more confidence because the claims we make for them will be supported by a robust amount of data and a registration, ultimately.”

Ahead of its competitors, ICL was one of the first companies to have a biostimulant product – the turf sector’s H2Pro TriSmart wetting agent – registered under the new FPR.

The company is also busily trialling some potential new biostimulant products, such as one based on nitrogen-fixing bacteria and is already FPR-registered for use in agriculture. In future, the product could be used in peat-free growing in horticulture in place of traditional fertilisers to help reduce nitrogen inputs. “It has proven efficacy, but we need to look at it from an ornamentals perspective,” explained Sam.

He concluded: “Biostimulants can help overcome some of the issues seen in peat free, but its key to understand what biostimulant you’re actually using – and what effect it’s having on plant growth to get that benefit.”

Fair play! So, now that the flame of the 2024 Olympic torch has gone out, will biostimulants become part of your peat-free production regime? And will I finally do that triathlon? I certainly hope so!