Chili pepper extract and garlic extract are two important types of plant-derived natural products in agriculture. Simply put, garlic extract is mainly used as a “plant antibiotic” for sterilization and disease prevention, while chili pepper extract (mainly referring to industrial chili peppers) plays a unique role in biopesticides and a wider range of industrial fields due to substances such as capsaicin extracted from it.
Agricultural Applications of Garlic Extract
The core value of garlic extract lies in its powerful bactericidal and disease-resistant potential, primarily achieved through its active ingredients (such as allicin) and related derivative compounds.
Direct Application as a Plant-Derived Fungicide
Garlic extract has been developed into formal pesticide products for the control of bacterial diseases in specific crops. For example, China has approved an 8% garlic extract microemulsion for the control of bacterial angular leaf spot in cucumbers, applied via spraying (25-50 ml per acre). Its mechanism of action lies in allicin’s competitive inhibition of sulfhydryl compounds essential for pathogen growth, leading to protein inactivation and thus inhibiting pathogen growth.
Developing Novel Pesticides as a Lead Compound
The naturally occurring disulfide compounds in garlic have provided inspiration for scientists. A research team at South China Agricultural University, based on garlic extract, designed and synthesized a series of more structurally stable and more active disulfide derivatives. Among them, a derivative named compound D7 exhibited extremely high inhibitory activity against *Ulva pineapple*, the bacterium that causes bacterial leaf blight in rice (half-maximum effective concentration was only 0.87 μg/mL), and showed low toxicity to non-target organisms such as earthworms and bees, providing a new approach for the control of bacterial diseases in rice.
As a biostimulant, garlic extract can enhance crop immunity.
Garlic extract not only has direct bactericidal effects but also enhances the crop’s own resistance. A 2025 study showed that specific garlic extract nanoliposome formulations (such as EliceVakcina) significantly upregulated the expression of stress- and defense-related genes (such as PR1 and PR2) in peas and activated the thiamine (vitamin B1) biosynthesis pathway (increasing vitamin B1 content by 14.3%), thereby effectively preventing *Fusarium oxysporum* infection in peas.
Agricultural and Related Applications of Chili Pepper Extracts
It’s important to distinguish between two concepts: the chili peppers we commonly eat and “industrial chili peppers.” Ordinary chili peppers are primarily used as vegetables, while industrial chili peppers, due to their extremely high spiciness (more than 10 times hotter than ordinary chili peppers), are mainly used to extract capsaicin and capsanthin, which have wide applications in agriculture and specialized industries.
Preparation of Green Biopesticides
Capsaicin extracted from industrial chili peppers is a key raw material for manufacturing biopesticides. These biopesticides can be used to control agricultural pests. Compared to chemical pesticides, they are low in toxicity, have low residue, and are environmentally friendly, aligning with the development direction of green agriculture.
Production of Environmentally Friendly Repellents
Capsaicin also has a very special use: in the production of environmentally friendly repellents. It can be added to coatings and applied to cables, optical fibers, ships, and other facilities, utilizing its strong irritant properties to effectively repel rodents, shellfish, and other organisms from feeding and attaching, thus providing protection.
Extraction of Natural Colorants (Capsanthin)
Capsanthin extracted from industrial chili peppers is a high-quality natural orange-red pigment that can be used as a food additive or for dyeing fabrics. In order to obtain high capsanthin content, chili varieties with high pigment content (such as Pigment W7 and Pigment No. 5) are specially cultivated, with a capsanthin content of 2.5% to 5%.
Comprehensive Comparison of Garlic Extract and Chili Pepper Extract
| Comparison Dimensions | Garlic Extract | Chili Pepper Extract |
| Core Active Ingredients | Allicin, disulfide compounds, sulfur-containing organic matter | Capsaicin (capsaicin) |
| Main Mechanism of Action | Binding with sulfhydryl groups inactivates pathogen proteins; induces systemic resistance in crops | Contact and repellent effects; affects the nervous system of pests |
| Main Target Pests | Phytophthora blight, late blight, bacterial angular leaf spot, wilt | Red spider mite, root-knot nematode, cabbage caterpillar, aphid |
| Application Forms | Crude extract, microemulsion, nanoliposomes, pesticide lead compound | emulsion, nanoformation, repellent coating |
| Unique Advantages | Induces disease resistance, biostimulatory activity, synergistic effect | Strong repellent effect, significant contact killing effect, EPA residue limit exemption |
| Concentration Effect | Low concentration promotes growth, high concentration inhibits pathogens | Higher concentrations result in better killing effect |
Summary and Outlook
Significant progress has been made in the application of chili pepper and garlic extracts in agriculture:
1.Garlic extract, as a “plant antibiotic,” exhibits excellent performance in bactericidal and disease-preventing effects, not only directly inhibiting pathogens but also inducing crop immunity. The application of new formulations such as nanoliposomes has further enhanced its efficacy.
2.Chili pepper extract, as a “biorepellent and insecticide,” shows good effects against mites, nematodes, and other pests. The US Environmental Protection Agency’s recognition of its status as a biochemical pesticide has laid the regulatory foundation for its global application.
3.Future Development Directions:
- Formulation Optimization: New formulations such as nanotechnology and microemulsions will further improve the stability and bioavailability of extracts.
- Synergistic Combination: The synergistic effects of garlic with other plants (such as agapanthus) warrant in-depth research.
- Mechanism of Action Research: In-depth analysis of the molecular regulatory mechanisms of extracts on pathogens and crops using omics technologies.
With the development of green and organic agriculture, these two types of plant-derived extracts will play an increasingly important role in crop protection.
If you are interested in applications on a specific crop or specific formulations of a particular type of extract, I can provide you with more detailed information.