Applications of Organosilicon in agriculture

What is Organosilicon?

Organosilicon is a crucial and multifunctional adjuvant in agriculture. While not a pesticide or fertilizer itself, it significantly enhances the effectiveness of pesticides and fertilizers, thus often referred to as a “super helper for efficient agriculture.”

Organosilicon surfactants are a class of nonionic compounds renowned for their unique molecular structure, which contains silicon atoms. This structure endows them with superior properties unmatched by traditional surfactants. One of their most notable characteristics is their ability to drastically reduce the surface tension of water-based spray solutions. For example, at a concentration of only 0.1% (by weight), they can reduce the surface tension to approximately 20-23. With a surface tension of mN/m, significantly lower than traditional surfactants, this low surface tension allows spray droplets to spread rapidly and evenly across the leaf surface, covering a larger area and ensuring more uniform contact with the target material. In addition to its excellent spreading properties, silicone surfactants are also known for their superior wetting and penetrating properties. The waxy cuticle on plant leaves typically hinders chemical absorption, but solutions containing these silicone-based adjuvants penetrate more easily. This facilitates faster and more efficient absorption of active ingredients by plant tissues.

Driven by the growing demand for high-performance agrochemicals and the increasing adoption of sustainable agricultural practices, the global agricultural silicone market is experiencing robust growth. It is projected to reach $1.5 billion by 2025, with a CAGR of 7% over the forecast period (2025-2033). Key drivers include the increasing demand for enhanced crop protection, improved soil health, and increased agricultural productivity. The growing prevalence of plant diseases and pests, along with increasing concerns about the environmental impact of traditional agrochemicals, is driving the adoption of silicone solutions.

What products can organosilicon be compounded with?

Organosilicon is an excellent adjuvant in agriculture and can be compounded with a variety of products. Its compounding targets can be divided into three main categories: pesticides, fertilizers, and other plant growth regulators/biostimulants.

When organosilicon is mixed with pesticides:

1. Insecticides/Acaricides

• Contact pesticides: such as pyrethroids (e.g., lambda-cyhalothrin), organophosphates (e.g., chlorpyrifos). Organosilicon helps the pesticide coat the insect’s body and penetrate the waxy layer on the insect’s surface, significantly improving contact effectiveness.

• Systemic pesticides: such as imidacloprid, thiamethoxam, etc. Organosilicon promotes rapid absorption and translocation of the pesticide by plant leaves, causing pests to be poisoned more quickly when feeding.

• Effects: Increases knockdown speed, reduces dosage, and is particularly effective against small pests or those with waxy protection (e.g., aphids, whiteflies, scale insects).

2. Fungicides

• Protective fungicides: such as mancozeb, chlorothalonil, etc. These pesticides need to form a uniform film on the plant surface to prevent pathogen invasion. The strong spreadability of organosilicon allows for more comprehensive coverage, leaving no blind spots.

• Systemic fungicides: such as triazoles (tebuconazole, difenoconazole), methoxyacrylates (pyraclostrobin), etc. Organosilicon can promote their penetration and absorption, making the effect faster and deeper.

• Effectiveness: Especially suitable for pathogens that infect on the underside of leaves (such as downy mildew), ensuring that the solution reaches hard-to-reach areas.

3. Herbicides

Functions: This is an area where organosilicon has been very successful.

• Improved penetration: Helps herbicides penetrate the waxy and cuticle layers of weed leaves, especially for hard-to-control broadleaf and perennial weeds.

• Enhanced resistance to rain washout.

Precautions:

Selective herbicides: Extra caution must be exercised when using them, as organosilicon may increase the risk of herbicide damage to crops. Always strictly follow the instructions to confirm whether the herbicide allows the addition of organosilicon.

Non-selective herbicides: such as glyphosate, glufosinate. Adding organosilicon can significantly improve the speed and effectiveness of weed control, especially in dry conditions, when weeds are mature, or when the waxy layer is thick.

When organosilicon is used in combination with fertilizers:

1. Foliar Fertilizers

• Macronutrient foliar fertilizers: such as nitrogen, phosphorus, potassium, etc.

• Micronutrient foliar fertilizers: such as calcium, magnesium, boron, zinc, iron, etc. This is the most common compound combination.

• Effects:

Significantly improves nutrient absorption efficiency and quickly resolves nutrient deficiencies.

For elements like calcium, which have poor mobility within plants, adding organosilicon during foliar supplementation can increase their absorption and translocation.

2. Liquid Organic Fertilizers/Biostimulants

• Amino acid-based, alginic acid-based, and humic acid-based fertilizers.

• Effects: Organosilicon can promote the absorption of these macromolecules or active substances by leaves, allowing their biostimulatory functions (such as root promotion and stress resistance) to be exerted more quickly.

When organosilicon is used in combination with other plant growth regulators:

• When combined with growth regulators such as gibberellic acid, brassinolide, and sodium nitrophenolate.

• Effects: Promotes the absorption of regulators, making their effects more rapid and consistent. However, the risk is that it may amplify the effects of the regulators or cause phytotoxicity; therefore, the concentration must be carefully controlled.

Crucial Precautions and Contraindications

1. Primary Principle: Test Before Widespread Application

Before mixing any new product, always conduct a “compatibility test” in a small container. Mix the components in the predetermined proportions, shake, and let stand for 15-30 minutes. Observe for any precipitation, flocculation, stratification, heating, or clumping. If any abnormalities occur, do not mix.

2. Strictly Adhere to the Usage Concentration

More organosilicon is not better! Excessive concentration can easily cause phytotoxicity, manifesting as leaf burn and wilting. It is essential to strictly follow the recommended concentration on the organosilicon product instructions, typically a dilution ratio of 3000-5000 times.

3. Avoid Mixing with These Products

Mineral oil/emulsifiable concentrates: These already have strong penetrability; mixing them may exacerbate phytotoxicity.

Sulfur-containing preparations: Such as lime sulfur mixtures and certain sulfur suspensions, which may react with organosilicon at high temperatures, increasing the risk of phytotoxicity.

Alkaline pesticides: such as Bordeaux mixture (copper-calcium preparation) and rosin mixture, may lose their effectiveness in an alkaline environment due to the potential damage to their organosilicon structure.

Some pesticides prone to causing phytotoxicity: Exercise extreme caution during the crop’s sensitive growth stages.

4. Environmental and Crop Factors

Avoid high temperatures and strong sunlight: Use with caution when temperatures exceed 30℃ or under strong sunlight, as this closes plant stomata and softens the waxy layer, making them more susceptible to phytotoxicity.

Sensitive crops and stages: Use with caution during the seedling, flowering, and tender shoot stages. For some pesticide-sensitive crops (such as peaches, plums, and apricots), a small-scale trial should be conducted first.

5.Prepare and use immediately: Mixed pesticide solutions should be used as soon as possible and should not be stored for extended periods to prevent loss of effectiveness or adverse reactions.

Summary Table

Compound Category	Specific Examples	Main Functions	Key Risks/Cautions
Insecticides/Acaricides	Imidacloprid, Lambda-cyhalothrin	Enhances contact and systemic action, covers insect bodies	May increase toxicity to beneficial insects such as bees
Fungicides	Mancozeb, Tebuconazole	Provides comprehensive coverage, promotes systemic absorption	Caution: Potential interactions with sulfur-containing formulations
Herbicides	Glyphosate	Significantly improves penetration into weeds	High risk of crop selectivity, exercise caution
Follicular Fertilizers	Micronutrient Fertilizers, Amino Acid Fertilizers	Greatly improves nutrient absorption efficiency	Excessive concentration may burn leaves
Plant Growth Regulators	Brassinolide	Promotes absorption, more consistent effects	May amplify phytotoxicity or regulatory effects

In summary, organosilicon plays the role of a “performance enhancer” in agriculture. Through its superior wetting, spreading, and penetrating abilities, it significantly improves the utilization rate of pesticides and foliar fertilizers, thereby achieving multiple goals such as cost savings, reduced residues, enhanced efficacy, and environmental protection. The scientific use of organosilicon is a crucial technology in the development of modern precision agriculture and green agriculture.