Biostimulants: What They Are & How To Use Them

There are numerous challenges facing the agriculture and horticulture industries today, many of which are a direct result of industrial activity and climate change. Unsurprisingly, the things that put more stress on humans — more extreme temperatures, increasing amounts of radiation, heavy metals, soil salinity, and pollution — put more stress on plants as well. In an interesting twist, biostimulants appear to be able to make our crops better able to handle these stresses (referred to as abiotic stresses). Read on to find out what plant biostimulants are and how they could help to boost your crops.

What Are Biostimulants?

Biostimulants, or plant biostimulants (PB), are substances or microorganisms that are applied in minute quantities in order to improve a plant’s uptake of nutrients and increase its ability to tolerate abiotic stress. The end goal is to make agriculture more efficient and also more sustainable by reducing the amount of fertilizers and pesticides needed.

While biostimulants are currently marketed under the labels of “fertilizers” or “pesticides” to fit the existing EPA categories, neither label is actually correct. Rather, they are organic and inorganic substances that contain hormone-like compounds, beneficial bacteria, acids, minerals, and other microorganisms that work to optimize a plant’s ability to adapt to its environment and make more efficient use of the resources in the soil.

The Top Biostimulants on the Market

While it’s a relatively new field of production, there are already several kinds of biostimulants on the market:

1. Inorganic Compounds

This category of plant biostimulants includes mineral-based molecules such as phosphites from phosphorous acid and minor elements such as silicon.

2. Beneficial Microbes

Beneficial microbes include live fungi or beneficial bacteria that “inoculate” the soil and help the plant to better defend themselves against pests and disease. Bacillus pumilus is an example of a beneficial bacterium that is currently being marketed for use as a fungicide.

3. Plant and Seaweed Extracts

Seaweed and algae are well known for their nutrient content and the presence of plant hormones like cytokinins. Biostimulants containing plant extracts are thought to stimulate the metabolism of the plants where the extract is applied and strengthen the plant’s own response to threats.

4. Humic and Fulvic Acids

Humic and fulvic acids can be found in topsoil where organic matter has broken down. Examples of biostimulants include worm castings and worm tea, which are both intended to be diluted before use.

5. Protein Hydrolysates

Just as amino acids and small peptides form the building blocks of proteins in the human body, they also help to synthesize proteins in plants — affecting the plant’s development and its ability to tolerate stress.

6. Biopolymers

This final category includes animal and plant-derived molecules like chitosan from crustacean shells that are used for plant defense and yield increase.

Choose the Right Plant Biostimulants

With so many kinds of biostimulants available, choosing one to try on your crop can seem like a daunting task. To make the decision easier, decide on a crop you’d like to focus on and a specific outcome that you’d like to see. For instance, would you like to see less powdery mildew on the leaves? More fruit? More plant growth? A reduction in the amount of pesticides or fertilizers needed? 

Once you’ve decided on your goals, look at the biostimulants that are available, and select those that are suited to your crop type and/or those that have delivered the results that you’re after. Ideally, you would choose a product that lists all of the specific ingredients and has third-party lab-test results to back up any claims that it makes.

Take a Research-Based Approach

1. First, Do No Harm

After selecting the biostimulant(s) that you plan to use, test the product on a small area of plants and keep them under observation for a week. If the product doesn’t cause any phytotoxicity or other harmful effects on the plants, you can go ahead and apply it to a larger area.

2. Keep a Control Group

After performing your initial test, apply the plant biostimulant to an entire field or section of your orchard according to the instructions on the label. Keep the same amount of plants untreated to compare the results both with and without. Make sure that all of the other conditions (irrigation, fertilization, etc.) are exactly the same in order to clearly identify the products’ effects.

3. Record the Results

As the season progresses, record the effects of the product as you go, measuring something that’s easy to quantify:

• Color
• Plant yield
• Leaf size
• Plant height
• Presence or absence of disease
• Presence or absence of pests
• Amount of fertilizer needed
• Amount of pesticide needed

It can also be helpful to record any environmental conditions that might also have an effect on your crop, as the effect of environmental changes on the effectiveness of biostimulants is thus far unknown. 

4. Follow Up

At the end of the harvest, you should clearly be able to see how the biostimulants affected your crop according to the parameters you decided to measure. You can then use this information to plan for the following year and either switch to a different biostimulant, apply the product to a larger area, or return to your former practices if the product had an undesirable effect.

Enhance Your Yield with Plant Biostimulants from Fruit Growers Supply Company

A pioneer in the California industry, Fruit Growers Supply continues to be dedicated to helping growers increase their yields in an economically and environmentally sustainable way. Over the past 110 years, we’ve seen a lot of changes and innovations develop and are excited to share the most recent developments. For niche biostimulants, soil amendment products, custom irrigation, and anything else you might need for your crops, contact our knowledgeable team today!