The increasing demand for alternatives to synthetic and traditional chemistries has led to a surge in the use of biologicals. Biologicals, derived from natural sources, such as microorganisms, plant and seaweed extracts, and minerals, offer a promising alternative or complement to conventional crop management practices. They encompass a wide range of products, including biostimulants and biocontrols, each with unique mechanisms and potential benefits. Generally, biostimulants can enhance plant growth, nutrient uptake and stress tolerance, while biocontrols offer a biological approach to managing pests and diseases. However, the relative novelty of the biologicals market brings challenges, including a lack of standardization and transparency, making it crucial for growers to carefully evaluate products before incorporating them into their operations. This article provides a short guide to understanding the complexities of biologicals, focusing on the importance of understanding mode of action (MoA) and observing crop responses for effective product selection and utilization.

Unraveling the Mode of Action: The Foundation of Informed Product Selection

The MoA is the cornerstone of understanding how a biological product interacts with the plant or its surrounding environment to produce the desired effects. A clear understanding of the MoA is essential for making informed decisions about product selection, application timing and expected outcomes. When evaluating a biological product, don’t settle for vague claims or marketing jargon. Instead, engage in a detailed discussion with your supplier, asking specific questions to uncover the precise mechanisms behind the product’s purported benefits.

What is the specific mode of action of this product?

This is the most critical question. General statements like “improves plant health,” “enhances stress resistance,” or “boosts nutrient uptake” are inadequate. Demand a detailed explanation of the specific mechanisms involved. For instance, if a product claims to improve nutrient uptake, ask about the specific nutrients affected, how uptake is enhanced, the duration of the effect and the scientific evidence supporting these claims.

Has this MoA been proven in your specific product?

Don’t assume a product will work as claimed simply because it contains an ingredient known to have certain effects. For example, the presence of humic acids in a product doesn’t automatically guarantee improved soil structure. Request specific research data, such as field or greenhouse trials, demonstrating the product in its final formulation exhibits the claimed MoA.

Why are application timing, rate and method important?

A well-defined MoA should provide a clear rationale for recommended application practices. If a supplier dismisses the importance of application timing, rate or method (e.g., in-furrow vs foliar), it raises concerns about the validity of the MoA. Just as we demand precision and evidence-based recommendations in critical areas like healthcare and food safety, we should hold biologicals to the same rigorous standards. A credible supplier should be able to explain why specific application practices are necessary to optimize the product’s effectiveness.

Has this been proven in your specific crop?

Avoid extrapolating results from one crop to another without scientific backing. Ensure the product has been tested and proven effective in your target crop. Inquire about the presence and functionality of the biological pathways and genetic mechanisms required for the MoA to operate in your specific crop. Differences in crop physiology, genetics and developmental stages can significantly influence a product’s efficacy.

Observing Crop Responses: Validating Effectiveness in the Field

While a thorough understanding of the MoA is essential, observing how your crop responds to a biological product provides valuable real-world insights into its effectiveness. The following are general observations that may indicate a positive response to biostimulants, recognizing that responses can vary significantly depending on the crop, product type and environmental conditions:

Improved Stress Resistance, Tolerance, or Recovery

•  Stress Resistance: This might manifest as reduced wilting or foliage loss during periods of drought, excessive heat or flooding compared to untreated plants.

• Stress Tolerance: Look for reduced yield loss despite prolonged exposure to abiotic or biotic stresses. Plants may still exhibit signs of stress, but the overall impact on yield and quality should be minimized.

• Recovery: Observe for faster recovery from stress events, such as drought or heat, compared to untreated plants. This could include a quicker resumption of growth, minimized yield loss after the stress is alleviated, or even enhanced stress resistance in subsequent seasons for perennial crops due to epigenetic priming.

Enhanced Crop Quality

• Color: Improved color development, particularly richer or deeper colors in fruits and vegetables, can indicate increased anthocyanin production. This can enhance the visual appeal and market value of produce.

• Consistency: Observe if a greater proportion of the yield meets higher quality standards for size, shape and uniformity. This can lead to better pricing and reduce the amount of produce falling into lower quality grades.

• Taste/Flavor: Improvements in BRIX levels, which measure sugar content, as well as increased levels of flavanols, condensed tannins and other flavor-related compounds can enhance the taste and flavor profile of the crop. These improvements may translate to premium prices and increased consumer preference.

• Nutritional Profile: Some biostimulants can influence the nutritional composition of crops, leading to increased antioxidant production, improved fatty acid profiles, or a more desirable balance of essential nutrients, which can add value to the crop.

Effects on Harvest Timing and Crop Development

Some biostimulants may promote slightly earlier harvest, depending on the specific crop and the criteria used to determine harvest maturity. This can be advantageous for growers, allowing them to bring their produce to market sooner.

Mild, Transient Stress Response

It’s not uncommon to observe a mild stress response within the first 48 hours after applying a biostimulant. This might manifest as slightly slowed growth or a localized hypersensitive response, characterized by minor cell death or damage. This transient response typically indicates the plant’s adaptation to the product and should resolve within seven days. If the stress response persists beyond this timeframe, it could suggest that the application rate was too high or the timing was not appropriate for the crop’s developmental stage.

Biocontrols: Assessing Effectiveness in Disease Management

When utilizing biocontrols for disease management, look for the following indicators of success:

• Reduced disease incidence: This indicates that the biocontrol agent is effectively preventing or limiting the establishment of the disease in the crop.

• Delayed disease onset: Even if the disease eventually appears, a delay in its onset can give the crop a competitive advantage and potentially reduce overall disease severity.

• Slowed disease progression: This suggests that the biocontrol agent is actively suppressing the development and spread of the disease within the plant.

• Measurable disease remediation: In some cases, biocontrols can actively reduce the severity of existing disease symptoms, contributing to plant recovery.

• Potential benefits for pesticide resistance management programs: By providing an alternative and often multifaceted and complex MoA, biocontrols can play a valuable role in managing pesticide resistance, prolonging the effectiveness of conventional disease management tools.

Getting the Right Answers

It can be difficult and confusing to get the answers to these questions, both for growers and for the suppliers manufacturing and producing the products. At Foresight Agronomics, we utilize Transcriptomic analysis, a study of how products affect crop gene expression, to figure out the right questions to ask and get answers to these questions. We specialize in the complexity and nuance of biological product research and development. We utilize cutting edge molecular biology tools like Transcriptomic analysis to demystify biologicals and provide reliability and credibility that helps growers and agriculture suppliers feel good about their biological product recommendations and investments.

Biologicals offer a compelling pathway toward more resilient agricultural systems. However, navigating the complexities of this evolving market requires a discerning approach. By prioritizing a thorough understanding of the MoA and carefully observing crop responses, growers can make informed decisions about product selection and application, maximizing the potential benefits of biologicals. Integrating scientific knowledge with practical field observations empowers growers to effectively incorporate these valuable tools into their management strategies.

Layne Ellen Harris, Ph.D, is the principal of Foresight Agronomics, LLC, an agronomic an genomic research consulting company based in She can be reached through her website www.foresightagronomics.com on LinkedIn at Layne-Ellen-Harris-pHd.