Newsletter (NL 2025-06) — Vetiver & citrus greening: attention researchers; A meta review of VGT slope stabilization; Vetiver roots tensile strength; Women farmers, tenure security and Vetiver; Regional Conference in India

In this Newsletter, among others, we present some interesting observations and research findings that underscore the importance of further research for deepening and expanding our understanding of how the Vetiver System can contribute to a climate-resilient, sustainable future. The first comes from Dr. Mani Skaria, whose observations in his citrus plantations led him to hypothesize that Vetiver may have an important role to play in the management of the devastating disease of citrus trees known as “HLB” or “citrus greening”. Citrus greening is considered one of the most serious threats to the citrus industry worldwide. The other comes out of reviews and research on the tensile strength of Vetiver roots, a critical factor for Vetiver’s role in slope stabilization and in bioengineering designs. One recent study (Chakraborty and Khan, 2024) suggests that the tensile strength of Vetiver roots may be significantly less than 75 MPa, a figure established by Nilaweera & Henchaovanich (1996) and wdely cited and used. Another (Torres, et al, 2020) study, however, found that it may be significantly greater than 75 MPa.  Given that quantitative field studies are as yet still limited, with much of the published data evaluating vetiver’s effects coming from laboratory bench-scale experiments and/or computer simulations, more field research is clearly called for to better quantify impacts at relevant geospatial scales.

Vetiver: Sustainable/Resilient Citrus Farming and a Call for Research

Dr. Mani Skaria, a distinguished plant pathologist and the visionary behind the US Citrus Company in south Texas, shared his pioneering work on integrating Vetiver grass into citrus cultivation with an audience at the recent Regional Vetiver Conference in Raipur, Chattisgarh, India.

In his presentation, he outlined the formidable obstacles confronting citrus growers in South Texas; a region plagued by a volatile climate, swinging from devastating freezes to prolonged droughts. Compounding these weather extremes is the persistent threat of Citrus Greening Disease (HLB), a tremendously destructive illness spread by the Asian Citrus Psyllid (ACP). It has spread across over fifty-eight countries across Asia, America, Africa, Oceania, and the Caribbean, and has resulted in billions of dollars in losses for the citrus industry worldwide. At present there is no cure for infected trees and control of the psyllid vector with pesticides is costly and challenging as the psyllids develop resistance to chemical pesticides.

Drawing on his own experiences, Dr. Skaria detailed the remarkable and well-documented benefits of interplanting Vetiver with citrus trees. During severe drought conditions, Vetiver’s deep root system has helped retain soil moisture, reducing the need for irrigation. In the face of freezing temperatures, the dense foliage of Vetiver provides a natural, insulating blanket, shielding vulnerable young citrus trees from the cold.

The potentially most groundbreaking aspect of Dr. Skaria’s presentation was his preliminary field observations regarding Vetiver’s potential impact on pest management. He noted that citrus trees interplanted with Vetiver appeared to show less pressure from the Asian Citrus Psyllid. Dr. Skaria hypothesizes that the dense, high-silica foliage of Vetiver may create a physical or sensory barrier that deters the psyllid.

As Dr. Skaria has noted this is a promising, yet anecdotal, finding from a specific field setting. It remains to be substantiated by rigorous research and, therefore, should not be considered either a proven or a recommended control practice at this stage.

However, the implications of this observation, if validated, would be profound. A non-chemical, plant-based method for deterring ACP could revolutionize the global fight against HLB, which currently relies heavily on costly chemical insecticides. Dr. Skaria’s observation serves as an urgent and compelling call to the scientific community. We strongly encourage entomologists, plant pathologists, and agricultural researchers to design and conduct controlled studies to determine if Vetiver grass can be a scientifically validated, effective component in an Integrated Pest Management (IPM) program for citrus. Verifying this potential could unlock a new, sustainable tool for an industry in critical need of solutions.

Dr. Skaria’s work provides a powerful testament to the multifaceted benefits of Vetiver. His presentation is a must-watch not only for its insights into sustainable agriculture but also for its potential to spark a new and vital avenue of scientific inquiry.

Review Confirms Vetiver as a Premier Climate-Adaptive Tool for Slope Stability

A comprehensive review published in 2024 in ASCE’s Natural Hazards Review makes a very good contribution to our understanding of Vetiver grass as a critical, nature-based tool for addressing the increasing threat of landslides fueled by climate change. The paper, “Soil Bioengineering Using Vetiver for Climate-Adaptive Slope Repair: Review,” by Avipriyo Chakraborty and Dr. Sadik Khan, synthesizes findings from 131 publications to illustrate Vetiver’s effectiveness in slope stabilization.

The review highlights that rising global temperatures are leading to more frequent and intense rainfall events, which are a major trigger for landslides worldwide. In this context, soil bioengineering with Vetiver emerges as an effective, cost-efficient, and environmentally friendly alternative to traditional, hard-engineering methods.

Key Findings from the Review:

Mechanical and Hydrological Powerhouse. The strength of the Vetiver System lies in its dual mechanical and hydrological function.

• Deep, Strong Roots: Vetiver’s dense, bushy root system can grow up to 3 meters deep, mechanically reinforcing the soil. Studies show the roots possess a high tensile strength of at least 17 MPa (see tensile strength article, below), which significantly increases the soil’s shear strength and cohesion.
• Reduced Water Pressure: Vetiver effectively reduces pore water pressure, a primary cause of slope failure, by absorbing excess soil moisture through evapotranspiration. Field monitoring has shown a significant drop in pore water pressure on slopes planted with Vetiver compared to non-vegetated slopes.

  

• Improved Stability: Numerous numerical analyses confirm that planting Vetiver increases a slope’s Factor of Safety (FOS). One study on a high-plasticity clay levee showed Vetiver could maintain a stable slope (FOS = 1.4) during a major storm, whereas the unrooted soil failed (FOS = 0.6).
• Early Warning System: Soil reinforced with Vetiver roots exhibits ductile behavior (i.e., being pliable and flexibility), meaning it can undergo greater deformation before failure. This characteristic can provide a valuable early warning of an impending landslide.

Proven Performance and Adaptability. The review confirms Vetiver’s wide-ranging applicability and effectiveness.

• Runoff and Erosion Control: Vetiver is highly effective at reducing surface runoff and soil erosion. Field studies in various climates and soil types have demonstrated runoff reductions of up to 69%.
• Climate and Soil Tolerance: The paper reaffirms Vetiver’s remarkable adaptability. It thrives in tropical, dry, and temperate climate zones (Köppen-Geiger classifications A, B, and C) and a vast array of soil types, including challenging sandy silts and high-plasticity expansive clays. In the United States, it has high growth potential throughout the Southeast, much of the South-Central region, and parts of the West Coast.
• Shallow Landslide Solution: The authors note that Vetiver’s impact diminishes with depth, making it an exceptionally well-suited solution for the common problem of shallow landslides, where the slip surface is within the root zone.

A Community-Based, Cost-Effective Solution. Beyond its technical merits, the review emphasizes Vetiver’s significant socioeconomic benefits.

• Low Cost, Easy Implementation: Vetiver is cost-effective and requires less initial maintenance compared to traditional structural solutions. Crucially, it can be implemented without heavy machinery, making it ideal for community-based initiatives, especially in remote areas.
• Economic Opportunities: The cultivation of Vetiver can create income opportunities for local communities. Its fragrant roots are used to produce valuable essential oils for the cosmetic and perfume industries, and its leaves can be used for handicrafts.
• Environmental Co-Benefits: Vetiver is also a powerful tool for phytoremediation, capable of removing heavy metals and other contaminants from soil and water.

This extensive review provides compelling, consolidated evidence that Vetiver grass is an affordable, long-lasting, and multi-beneficial technology for landslide mitigation. As the world seeks sustainable and resilient solutions to climate change impacts, the Vetiver System stands out as a proven, practical, and community-empowering approach to protecting our landscapes and infrastructure.

Study Suggests That Vetiver Root Tensile Strength May Be Significantly Higher Than Design Standards

A comprehensive experimental study by Torres et al. (2020), published in Informes de la Construcción, provides robust new data on the tensile strength of vetiver grass roots, with findings that could significantly impact future bioengineering designs. The research found that the actual tensile strength of vetiver roots tested was substantially higher than the 75 MPa value commonly used in slope stabilization designs.

The investigation was extensive, involving 305 tensile strength tests performed on the primary root system of vetiver plants. To ensure broad applicability, the vetiver was planted in three different soil types—silty sand (SM), uniform sand with silt (SP-SM), and low-compressibility clay (CL)—and tested at various growth stages, ranging from 4 to 65 weeks.

Key Findings:

• Significantly Higher Strength: Across all soil types and ages, the study found a mean tensile strength of 118.50 MPa and a mode (the most frequently occurring value) of 131.71 MPa.
• Design Standard Undervalued: The results show that the widely accepted design value of 75 MPa may be highly conservative. In this study, 75 MPa corresponds to approximately the 5th percentile of the experimental data, meaning 95% of the tested roots exhibited higher strength.
• Strength vs. Diameter: The study confirmed previous findings that tensile strength is inversely proportional to the root’s diameter; smaller-diameter roots exhibit higher tensile strength. The ultimate load a root can bear increases with its diameter, following a predictable power-law relationship.
• Influence of Growth Conditions: Statistical analysis indicated that both the soil type and the age of the plant have a statistically significant influence on the root’s tensile strength. The study was conducted under controlled tropical climate conditions without subjecting the plants to water stress, which may influence root development.

This research raises the question that the vetiver root system may be much stronger than previously assumed in many engineering applications. The mean value of 118.50 MPa—more than 50% higher than the 75 MPa standard—would suggest that bioengineering designs using vetiver for slope stabilization may have a greater margin of safety than calculated. The authors recommend further studies to analyze the effect of cellulose content and “pull out” resistance for a more complete understanding of vetiver’s remarkable capabilities.

Managing Land for a Greener Future: How Women and Women’s Tenure Rights Can Drive Climate-Smart Farming with VS

Globally, women comprise approximately 43% of the agricultural labor force in the Global South. In Sub-Saharan Africa, this figure can approach 50% or more, with female-headed households alone accounting for approximately 20–30% of farms. In Latin America, women represent around 20–30% of agricultural workers, while female-headed farming households  in Nicaragua, Colombia, Guatemala, Peru, Honduras, and El Salvador being a prominent feature. South Asia also has substantial female participation rates, averaging between 30–45%, with female-headed households comprising roughly 10–20%. In Southeast Asia, women’s participation reaches about 50% in countries such as Vietnam, Laos, Cambodia, and Indonesia, with female-headed farms typically between 15–20%. East Asia, notably China, sees women making up approximately 40–45% of agricultural laborers, though female-headed households are much fewer, around 10–15%.

This is extremely important to note when considering how to scale up the Vetiver System for climate-smart farming. Evidence shows that female farmers tend to be more motivated than their male counterparts to adopt sustainable agricultural practices, invest in long-term resource management, and prioritize soil and water conservation. For example, studies in Sub-Saharan Africa reveal that women-led farms exhibit higher rates of erosion control, agroforestry, and organic methods. Similarly, in South Asia and Southeast Asia, female farmers regularly employ conservation agriculture techniques, such as crop diversification and reduced chemical input usage. In Latin America, women farmers, particularly heads of households, are amongst the most active participants in land conservation and watershed management initiatives. East Asian women farmers also exhibit strong tendencies towards resource-conscious agriculture, influenced by societal roles emphasizing community well-being and long-term productivity.

Women’s good stewardship, however, is frequently faced with significant barriers. In particular, the lack of secure land tenure is a critical impediment; when women have secure rights to the land they farm, they are demonstrably more likely to invest in long-term conservation measures, such as planting trees and implementing soil conservation structures. Conversely, where their tenure is insecure, the incentive for such long-term investment is diminished. A recent report from Landesa, a global land rights organization, underscores this critical link between empowering women with secure land tenure and advancing climate change mitigation and adaptation efforts. The report’s findings, when viewed alongside the proven benefits of the Vetiver System for soil and water conservation, present a powerful case for focusing on female-headed smallholder households as key agents of sustainable agricultural transformation.

The Landesa report, “Women’s Land Tenure Security as a Pathway to Climate Change Mitigation and Adaptation,” argues that secure land rights for women are not just a matter of social equity but a vital strategy for building a more climate-resilient world. The report identifies three primary avenues through which this positive impact is channeled: sustainable management of forest resources, increased long-term land investments, and an expanded range of response options to climate shocks.

For female-headed smallholder households, the connection between land tenure and long-term investment is particularly pronounced. The report highlights strong evidence from Sub-Saharan Africa showing that when women have formal or documented rights to their land, they are significantly more likely to invest in sustainable land management practices. These investments include crucial soil and water conservation measures, which are the cornerstone of climate adaptation in agriculture.

This is where the Vetiver System comes in as a simple, low-cost, and highly effective tool to combat soil erosion, conserve water, stabilize slopes, and help in the control of some important insect pests. For smallholder farmers, establishing vetiver hedgerows can dramatically improve soil health and moisture retention, leading to more resilient and productive farms.

However, the decision to invest in a long-term solution like the Vetiver System, which requires time and labor to establish, is heavily influenced by a farmer’s confidence in their future access to and control over the land. The Landesa report emphasizes that the “durability, robustness, and completeness” of women’s land rights are essential for expanding their capacity to respond to climate change.

The report finds that insecure tenure often forces women into short-term, survival-oriented farming practices, neglecting long-term land stewardship. Conversely, when a female-headed household has secure tenure, the incentive to plant vetiver and reap its long-term benefits—such as reduced crop failure during droughts and protection of fertile topsoil—increases substantially.

A compelling, albeit inverse, example from the report illustrates this point: a study in Malawi found that men in matrilocal communities, where they have less secure land tenure, were less likely to invest in soil conservation measures, including planting vetiver grass. This finding reinforces the principle that secure tenure is a powerful motivator for long-term, land-improving investments, regardless of gender.

Bottom line: When female-headed households own or feel secure about the land they farm, they invest in exactly the kinds of soil- and water-conserving measures that Vetiver excels at. Efforts aimed at women’s tenure security can provide an entry point for delivering durable climate resilience and livelihood gains for some of the most vulnerable farmers by including making Vetiver planting material accessible, supporting women-specific extension, and reinforcing local conservation-related norms, and thus accelerate Vetiver System adoption.

Consideration, then, for translating these insights to Vetiver System uptake by female-headed smallholder farms includes:

• Vetiver = a “long-term land investment”. The report confirms that women invest in permanent soil-conservation infrastructure once their rights are clear and durable. Programs aimed at securing tenure should explicitly list Vetiver planting among the incentivized investments.
• Target the tenure–technology bundle, not technology alone. Bundle land certification with Vetiver starter kits (slips + training) for newly titled women. In Rwanda, for example, there was a post-regularization surge in bund/terrace building; Vetiver would have served that purpose and is much easier and cheaper than terrace and bund building.
• Leverage women’s collective action for communal slopes, riparian strips, etc. Community forest/user groups that include women manage resources more sustainably and share income more equitably. Embedding Vetiver in the workplans of such groups (e.g., for gully plugging or riverbank protection) multiplies impact and ensures maintenance.
• Address custom and labor constraints head-on.  In matrilineal Malawi, security encouraged women to plant Vetiver grass, while insecure men hesitated. Where customs still sideline women, pair Vetiver promotion with mediation of inheritance norms, women-centered labor-sharing groups, and access to micro-credit or cash-for-work for initial planting.
• Count Vetiver hedgerows as an “adaptation option” in climate-finance proposals. The report notes that complete rights expand women’s response options, including irrigation and diversification. Because Vetiver reduces runoff, captures sediment, and can be harvested for handicrafts or mulch, it fits donor definitions of both mitigation and adaptation—funding windows that prioritize gender-responsive land tenure can thus underwrite Vetiver roll-outs.
• Monitor women-specific benefits. Evidence gaps remain on how tenure-enabled conservation translates into women’s income and bargaining power. Capture sex-disaggregated data on hedgerow length planted/maintained, reductions in labour/time for erosion control, revenues from Vetiver by-products, and reinvestment decisions within the household.

Landmark Regional Vetiver Conference Organized in India

The Regional Conference on Vetiver cum National Advisory Meeting for Sustainable Development was convened on 4–5 June 2025 in Raipur, Chhattisgarh in India. The conference brought together over 60 practitioners, researchers, and policymakers to share advances in Vetiver System technologies and chart a path for regional scale-up . Hosted by JACS Rao, IFS (R), CEO of the Chhattisgarh State Medicinal Plants Board and supported by The India Vetiver Foundation. A key objective of the conference was to leverage Vetiver’s broad range of benefits, particularly to provide better income for poor farmers in Chhattisgarh, to enhance soil health, and for water conservation.

Technical presentations spanned bioengineering applications—such as vetiver biochar for soil amendment and vetiver-derived ethanol for biofuel—to innovative models of community engagement under government schemes. Notably, discussions highlighted successes in integrating Vetiver hedgerows with water-body rejuvenation and the potential for formalizing Centres of Excellence to standardize best practices in planting, maintenance, and monitoring. Practitioners from diverse backgrounds—including geotextile innovators, desert-greening specialists, and Ayurvedic scholars—contributed case studies demonstrating Vetiver’s versatility.

Collaborative proposals emerged for Memoranda of Understanding with local agencies, support for water harvesting projects, and follow-up “road shows” in major Indian states to extend Vetiver adoption beyond Chhattisgarh.

Closing with a commitment to draft a “Raipur Declaration,” the conference underscored collective enthusiasm for regional conferences leading up to India’s hosting of the 8^th International Vetiver Conference (ICV-8) in 2027. Attendees expressed their gratitude to Mr. JACS Rao and his team for creating a transformative platform, setting a benchmark for future Vetiver events in India.