Back in 2021, as the world was struggling with the pandemic-related supply chain meltdown, one of the critical raw materials that became very hard to find was rubber. While supply chain issues tied to shipping snags have since been resolved, natural rubber supplies remain under threat from a combination of disease and shifting climate patterns. Researchers seeking out new sources of rubber have found some promising alternatives, including sunflowers and dandelions.
Nearly all the world’s rubber supply – roughly 90% – comes from Southeast Asia. Specifically, Thailand, Indonesia, Vietnam, and Malaysia accounted for roughly 70% of global export values in 2023. Côte d’Ivoire (Ivory Coast) in Africa has become a top supplier in recent years as well.
Most of the rubber trees in big production countries are clones of seeds exported from the plant’s native South America. Hevea brasiliensis, also called the Pará rubber tree, originated in the Amazon rainforest and is the source of 90% of all natural rubber produced. However, you would be hard pressed to find any rubber plantations in South America today due to a catastrophic blight disease that wiped out the industry back in the 1930s.
Major production countries maintain tight biosecurity measures, including restricted travel and trade from South America, but most believe it’s only a matter of time before South American Leaf Blight makes its way to Southeast Asia. In fact, there have been rumors that it’s already in Thailand and India. Experts warn that if the leaf blight were to make it from South America to Asia, the disease could wipe out most of the world’s natural rubber supply in short order.
Regardless of whether the blight from South America crosses borders, other local blights and lethal pathogens, such as white root disease, have jumped from palm plantations to rubber trees. The pathogens have spread exponentially amid an increase in frequent flooding, which along with drought are also increasingly impacting production.
The world’s dependence on rubber runs a lot deeper than many may realize. In the US alone, rubber is used in some 50,000 different products, including shoes, clothing, sporting goods, medical equipment, a multitude of household items, and more. That’s in addition so the roughly 330 million tires produced in the US annually. In total, America imports around 105 million tons of the stuff every year.
Although synthetic rubber can be produced from petrochemicals, natural rubber has unique properties which even these synthetics can’t match: natural latex gloves are more resistant to tear than nitrile ones, while aircraft tires use natural rubber for its high elasticity and resistance to hea.
Natural rubber is harvested mainly in the form of the latex. Over 2,500 plants produce various forms of latex , according to Katrina Cornish, professor of horticulture and crop science and food, agricultural and biological engineering at Ohio State University, “but just by happenstance, it’s all ended up being commercially produced from one species.”
Cornish mostly blames shortsightedness for the world’s dependence on a single species and a small growing region. Once a supply source was established, producers had little motivation to innovate. “I’ve spent 35 years trying to get people to understand the risk we’re taking by not being proactive about this,” she said.
Cornish and her colleagues have been working on methods to improve efficiency and increase latex yields from two sustainable North American plant sources: a dandelion species and a desert shrub called guayule.
Guayule latex comes from cells in the shrub’s bark. Extracting the latex involves grinding up the bark to break open its cells and release latex particles into a “milkshake.” Guayule contains a particularly attractive high-performance latex that is stronger and softer than any other known polymer, according Cornish, meaning more filler can be added in production without any loss of its valuable properties. The dandelion species, Taraxacum kok-saghyz, or TK dandelion, requires a similar extraction process.
Cornish is hoping to partner with flocculant chemists who could help further refine the processes for extracting latex from guayule and TK dandelion. Guayule is also being grown at a research and development farm in Arizona that’s operated by tire company Bridgestone.
Another source of rubber could be sunflowers, according to US-based Edison Agrosciences. The company initially relied in genetic modification to increase rubber content but has since shifted towards traditional breeding methods. According to CEO David Woodburn, the leaves of the sunflower plant contain 1 – 2% of their weight in natural rubber and is already grown on over 1 million acres in the US.
The biggest challenge at the moment for the company is generating demand for a product that essentially solves a future need. “The South American leaf blight hasn’t hit Southeast Asia yet, so it’s not a problem today,” Woodburn told AgFunder. “For the most part, there’s plenty of rubber available, but the industry definitely recognizes is that it’s a serious, serious problem.” For now, Edison Agrosciences is targeting “more specialty applications that have higher pricing and are clearly lower volume” before eventually moving on to commodity rubber. (Sources: Associated Press, AgFunder, Ambrook Research, Ohio State University)
