In today’s world, natural rubber is a critical component of developed economies — it remains impossible to drive a car, fly a plane or fight a war without it. However, because it is ubiquitous in our everyday lives, most people don’t realize its incredible importance.
In 2018, 13.96 million tonnes were collected by hand-tapping latex from rubber trees, mostly in tropical, Southeast Asian plantations and small-holdings.
The latex is about one-third rubber, which means that 3.7 billion U.S. gallons, enough to fill over 5,600 Olympic-sized swimming pools was dribbled into little cups. About 11 percent is centrifuged to remove half of the water, and the rest is converted to solid rubber.
Concentrated latex is shipped to manufacturers of articles such as gloves and condoms made by dipping formers into latex emulsions, whereas the solidified rubber is molded into articles like tires, bushings and gaskets. About 50,000 different products require natural rubber for their manufacture.
Biodiversification of global natural rubber is way past due. Natural rubber is the only critical agricultural product that has no backup. Synthetic rubber cannot replace it because of natural rubber’s unique, essential performance properties.
Rubber trees are produced by grafting clonal scions onto seedling rootstocks. Differences among clones are tiny, and genetic uniformity makes crop failure a serious risk to the global rubber supply.
Little rubber is produced in South America because of the endemic fatal rubber tree fungal disease, South American Leaf Blight. If this disease establishes in Southeast Asia, we could quickly lose our supply.
Even if rubber tree plantations remain productive, burgeoning demand (5.2-percent growth per year), increasing labor costs, restricted expansion of new plantings due to deforestation moratoria and climate change erosion of suitable acreage prevent rubber trees from meeting the expected doubling of demand during the next 20 years.
Addressing this demand, while minimizing ecological impacts, requires biodiversification and farming other rubber crops in temperate regions.
Countries in temperate zones import all the natural rubber they need. The last 15 years have seen significant investment from governments and tire companies into alternative rubber research and development of rubber dandelion and guayule.
However, much still needs to be done. Rubber dandelion must be domesticated before it can be cultivated as a field crop because it is slow to establish and grow and is easily swamped by weeds.
Historically, humans have taken thousands of years to domesticate and improve the crops we depend on today. This is clearly not an option for alternative rubber crops. Fortunately, recent progress in conventional and molecular breeding and genome-informed gene editing approaches can enormously accelerate these processes.
Even with these tools, we are still years away from widespread rubber dandelion mechanized farming. But this is not our only option, especially if a rubber supply catastrophe occurs, and we must produce our own rubber in a hurry.
Some rubber dandelions grow rapidly in hydroponics with rubber-producing roots becoming large enough for rubber extraction in a fraction of the time required in fields. Controlled-environment hydroponic dandelions have no weed or dirt and are not subjected to productivity limitations related to weather, day length or season.
Hydroponics can be extended to vertical farming — a controlled method of optimally growing crops in vertically stacked layers, becoming popular for produce, which takes up significantly less land than standard farming.
This is the approach being taken by American Sustainable Rubber Co (ASR), using technology and germplasm initially developed at Ohio State University (OSU).
An impressive advantage of hydroponic production is that roots can be harvested and then rapidly regrown — the same plants can be harvested multiple times through the year and make this 4D system many times more productive than a field crop with its single annual root harvest.
Thus, although viable yields may be possible in a few years on conventional rubber dandelion farms using chemical weed control and optimized fertigation practices, indoor vertical hydroponic systems have potentially at least 10-times higher productivity per acre per year and can be built up very quickly.
ASR and OSU have partnered to maximize rubber yield by trait selection and by editing the plant’s own genes to target the flow of carbon from photosynthesis to make larger roots with higher rubber quantities.
An in-depth understanding of the genes and enzymes responsible for rubber biosynthesis can inform additional gene modification approaches to increase rubber yield.
Without economies of scale, domestic natural rubber from limited acreages or a few vertical indoor farms cannot be produced at the same cost as the commodity form — not while tropical rubber is harvested from 8 million hectares of trees and tappers earn a couple of bucks a day.
Thus, premium markets, with higher margins than commodity products like tires, are essential while crops are at small-scale so that profits can fund expansion. Hydroponic systems produce a cleaner, dirt-free rubber that may have premium niche applications, which rubber extracted from field-grown roots cannot address.
Just the fact that this rubber is produced from U.S. dandelions could create value. Of course, if a significant supply disruption in tropical rubber supplies from disease or politics occurs, high rubber prices and government subsidies may quickly provide financial support for large-scale crop production and associated processing plants.
Dandelion and guayule rubber crops in conventional and/or vertical farms will add new cash crop options for our growers and reduce our dependence on Asian rubber imports, which currently supply all America’s manufacturing needs.
In the long term, U.S. rubber could expand to fully supply our own requirements and then allow the export of excess rubber to other countries.
Katrina Cornish, scientific advisor of American Sustainable Rubber Company, LLC, is the inventor of the T.K. Dandelion strain and is a global expert on alternate rubber and latex production, processing and products. She is the Ohio Research Scholar/Endowed Chair Bioemergent Materials at Ohio State University.