Growing America’s Future in Natural Rubber

Katrina Cornish is the Center Director for the U.S. Arid Land Agricultural Research Center (ALARC) in Maricopa, AZ, and a leading U.S. scientific expert on alternate rubber and latex production, processing, and production. Dr. Cornish and her research team are dedicated to developing sustainable agricultural systems, protecting natural resources, and supporting rural communities in arid and semi-arid regions through interdisciplinary research.

Welcome Dr. Cornish to Under the Microscope:

UM: What is the current state of U.S. domestic rubber production? Where is it grown in the U.S.?

KC: Natural rubber is a critical raw material for the security of the U.S. All sectors of our economy and defense absolutely depend on natural rubber. At the moment, all commercial natural rubber is imported, mostly from Southeast Asia. 

Three crops are being grown for rubber and latex in the U.S.: 

Guayule is a desert crop native to the Chihuahuan Desert of Mexico and southern Texas. It can live for at least 40 years in the wild. Wild Mexican guayule provided about 25% of the rubber needed by the early automotive industry in the U.S. When guayule is processed using an aqueous extraction process (which I invented at ARS in the 1990s), the rubber particle integrity is maintained, and a high-quality latex is the end product. Guayule solid rubber (gel-free) can be made from the latex or directly extracted with organic solvents. Guayule is grown in southwestern states, such as California, Arizona, and Texas. It can also be grown in New Mexico and some parts of Nevada, Utah, and Oklahoma. 

Rubber dandelion is native to Kazakhstan and adjacent regions. The rubber is produced in root laticifers (specialized latex-producing pipe-like vessels). The rubber does contain a gel fraction like the tropical rubber tree natural rubber. Rubber dandelion is grown as an annual crop. It is currently in several states and can be grown in most of the U.S. 

Sunflower was originally researched as a rubber crop by ARS and Colorado State University. One company is currently growing it in Missouri, North Carolina, and Kansas. Sunflower natural rubber is a lower molecular weight rubber but is highly promising as an active processing aid. 

Guayule field ready to harvest. (Photo by Katrina Cornish, ARS) 

UM: Is it hard to grow natural rubber in the U.S.?

KC: Not really. It would be hard to grow the rubber tree here, because it is a tropical tree. Also, tapping rubber trees can be too labor intensive for our workforce. 

However, guayule agronomy is well understood. Many farmers are interested in growing it as an alternative to alfalfa and cotton. It needs much less water, and irrigation water is severely restricted in the southwest. It is also grown as a perennial with seasonally independent annual harvests. Management practices are different depending upon whether a farmer is growing the crop for latex or for solid rubber.    

Rubber dandelion can also be easily grown in the northern states, but it is not yet fully domesticated. Stand establishment by direct seeding and weed control are major issues. The Ohio State University is developing naturally selected herbicide resistant lines, which will greatly help. This species may also prove useful as a winter crop in the southern U.S. 

UM: What are the benefits of using natural rubber versus synthetic products?

KC: Natural rubber and natural rubber latex are used in about 50,000 different products. In many of them, it is essential because the synthetic rubbers lack the properties needed. For example, airplane tires are 100% natural rubber, as are bushings, earthquake isolators, tank treads, snowmobile tracks, and many film and foam products. Even car tires are 50% natural rubber, and ones for electric vehicles have a higher percentage. Natural rubber is crack resistant, highly durable, and resilient. It has good heat dispersion and can take hundreds of thousands of deformations without damage over a wide temperature range. It is the best elastomer for ultracold applications. Synthetic rubbers are more solvent, chemical, and oil resistant than natural rubbers. 

UM: What are the key goals of ARS research related to developing domestic sources of natural rubber and latex?

KC: The key goals are:

• Understanding what slows down the biochemical process of making rubber.
• Increasing rubber yield by increasing the concentration of rubber particles produced in the rubber synthesizing tissues.
• Identifying and selecting plants that continue to synthesize rubber throughout the year, not just during the winter.
• Optimizing management practices to maximize rubber yield/acre.
• Developing seed stocks to support farmers.
• Developing robust and scalable extraction and purification technologies.

UM: How has ARS research contributed to reducing U.S. reliance on imported natural rubber?

KC: ARS has overcome most, but not all, of the technical obstacles preventing widespread adoption of rubber producing crops. Biochemical studies have revealed rate limiting metabolic steps to increasing rubber concentration, and a full set of molecular tools has been developed and proven. The enzyme complex responsible for making high quality rubber has been partially characterized. The material properties and composition of guayule latex and rubber have been determined, allowing identification of best products to prototype. 

Many prototypes of high value products have been made. ARS is hoping to build a latex extraction pilot plant at ALARC. When brought into operation, this will be able to supply sufficient latex to foster guayule research at multiple laboratories and companies, and lead to investment into processing infrastructure. This is the major limitation of domestic production.

 
Students, staff and faculty from the University of California, Merced (UC Merced) help with vacuum harvesting ripe guayule seed from ALARC fields under a Material Transfer Agreement with UC Merced and Texas Tech University, members of the U.S. National Science Foundation’s Engineering Research Center (ERC): Transformation of American Rubber through Domestic Innovation for Supply Security (TARDISS) partners. (Photo by Katrina Cornish, ARS)

UM: In what ways do scientific and technological innovations support stronger, more resilient supply chains in the rubber and latex sector?

KC: Scientific and technological innovations are focused on all aspects of rubber crop domestication: increasing yield, through the combination of increased biosynthesis and biomass, improving harvestability, extraction efficiency, and quality, valorizing coproducts, and inventing new products that confer market advantages or address unmet needs. Our current supply chain is enormously long and controlled by other countries. Domestic production is the only way to increase our supply chain resiliency. This includes bringing latex and rubber product manufacturing back to the U.S.. Rubber crops will also demand extensive processing infrastructure and a new industrial agricultural and industrial workforce across the U.S. 

UM: What major challenges arise when attempting to scale domestic rubber crops from minimal acreage to large‑scale production?

KC: The main issue is competing directly with low-grade Hevea rubber, which is not feasible for small-scale producers against massive commodity markets. Instead, guayule rubber should target niche markets, leveraging its superior qualities to justify higher prices. Guayule natural rubber and latex outperform synthetics and some high-grade Hevea in specific applications and can be used to make films that are softer, stretchier, and stronger than alternatives.

UM: Why is it strategically important to focus first on low‑volume, high‑margin markets when building a new U.S. rubber and latex industry? 

KC: It is the only way. Building full rubber independence without using product sales to fund expansion would cost more than the entire GDP. Production and extraction will start small but need to be profitable enough to support growth and through an iterative process will engulf more products into production pipelines until commodity scale is reached.

Early targets here include products used in aerospace and medicine. An important product that can uniquely be made with guayule natural rubber latex is the balloon that holds a tracheal tube in place when a critically ill patient is intubated in the intensive care unit. 

UM: What obstacles must be overcome to establish large‑scale rubber crop farms across the U.S.? 

KC: The primary obstacle is establishing extraction facilities associated with suitable downstream manufacturers. These, potentially, could be small or large and small ones could be owned and operated by farm co-ops. We also need programs to encourage farmers. Associated seed production will be essential to support scaling up. Fortunately, both guayule and rubber dandelion make large amounts of seed.  

UM: How do you see the natural rubber market expanding in the future? How does that benefit farmers? 

KC: The demand for natural rubber increases every year and will not level out until the entire world is developed and everyone has access to cars and roads. This will require at least twice the natural rubber currently produced. However, Hevea production acreage is pretty much already saturated, and oil palm competes for the same land without requiring the same degree of labor. New rubber tree acres would require massive destruction of our remaining rainforests, so it is not a viable solution. 

Thus, most of the projected increase in demand must come from alternatives, and the U.S. is one of only a few countries that have enough land. By 2050, we can have 17 million acres of rubber producing crops in the U.S. and be fully independent.

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