The sage-environmentally friendly, waist-significant shrub guayule could possibly search like just a person of the lots of scraggly bushes that dot the hills and valleys of the Chihuahuan Desert in Mexico and the southwestern U.S. But its nondescript stalks and leaves harbor a panoply of botanical treasures, such as rubber that Indigenous men and women employed hundreds of several years in the past to make balls for video games.
For many years, scientists have been investigating guayule (Parthenium argentatum) as a possible industrial resource of pure rubber. The market is now dominated by rubber sourced from Hevea brasiliensis trees in Southeast Asia, and it is really hard for guayule in the U.S. to contend with those massive functions, which have decrease labor expenses. Farmers in the Southwest tend to favor far more rewarding crops, these as alfalfa and cotton.
But two converging developments might be about to change guayule’s potential clients. Fungal infestations of monocultured Hevea trees have brought about steep drops in world all-natural rubber provides in the latest decades. Meanwhile the Southwest’s worst drought in much more than a millennium has lowered the h2o offered to farmers, earning it tougher to increase alfalfa, cotton and other thirsty crops. Guayule, on the other hand, is drought-tolerant. And it can be developed and harvested for many several years devoid of tilling the soil. That undisturbed soil stores carbon in the ground and stops erosion.
In an effort and hard work to make guayule a much more practical crop, scientists in academia and industry are operating to boost the plant’s rubber production—while also investigating uses for the sticky resin and woody content it makes. With guayule, “a farmer could nevertheless expand matters in the desert and still make a residing and still shield the soil and safeguard the drinking water,” suggests Catherine Brewer, a chemical engineer at New Mexico State College. “There are not numerous plants that meet up with all of those people conditions.”

The tire company Bridgestone has operated a demonstration-scale processing facility in central Arizona for the previous ten years in an work to exhibit that guayule can at some point be harvested for purely natural rubber at a industrial scale. In late August the company introduced it would commercialize guayule rubber generation by 2030. However two thirds of the world’s rubber is now produced synthetically from petroleum, rubber generated from normal sources is indispensable for some purposes. Airplane tires, for example, are created from all-natural rubber, which is excellent to synthetics for dealing with impacts this sort of as landing on the runway.
Mainly because only a compact volume of guayule is at this time grown, it would not be in a position to contend with Hevea rubber on a broad scale for some time, claims Katrina Cornish, who reports different rubber sources at the Ohio Condition College. That signifies corporations that want to use it would need to begin with higher-value products—such as the guayule-rubber racing tire Bridgestone debuted this calendar year. At her very own corporation, EnergyEne, Cornish focuses on premium goods made of guayule latex, a softer variety of rubber that the plant also will make. EnergyEne is producing a radiation-attenuating healthcare glove, for case in point. On the shopper facet, the firm has produced “lovely condoms,” Cornish adds, such as ones that are Cabernet Sauvignon- and Chardonnay-flavored. Guayule tends to make the greatest latex, as opposed with other pure and synthetic formulations, mainly because it’s especially robust, stretchy and smooth, Cornish states. It’s also hypoallergenic, not like latex derived from Hevea trees. Jason Quinn, a sustainability researcher at Colorado Point out College, done a examine in 2020 that found that guayule rubber grown on a regular-dimension Arizona farm could be cost-aggressive with Hevea rubber—though the guayule product’s value would be toward the bigger conclusion of the variety of historic Hevea selling prices.
At Bridgestone, plant geneticist David Dierig hopes to boost guayule’s profitability by breeding plants that bear more rubber. His staff has mapped guayule’s genome and recognized genes that are linked with better rubber written content. With this info, researchers can find vegetation with a prospective for bigger rubber output and cross them just before they are completely experienced, shortening the time it would normally choose to mature new generations. There is some restrict to how significantly rubber any plant can develop, Dierig claims, but it is difficult to know in which that restrict is. He claims that substantial-molecular-excess weight rubber—the form used for tires—was initially close to 2.8 percent of the plant, and he has brought it up to 3.8 per cent. “We have to get rubber articles to somewhere all over 6 percent to be right aggressive [with Hevea],” Dierig claims. Selling other items manufactured from the plant’s resin and woody areas, nevertheless, could enable guayule be competitive in advance of achieving that degree of rubber, he provides.
The woody stems offer a considerably less intensive choice for creating guayule merchandise to start to develop additional of a business incentive to cultivate the plant. In guayule processing, the bushes are floor up, and rubber and resin are extracted employing a solvent, leaving driving a dry, sawdustlike product referred to as bagasse. This can be pressed into particleboard these types of as the kind used in household furniture or most likely made into biofuels for ships and planes—the latter conversion involves pyrolysis, a course of action in which the bagasse is heated in the absence of oxygen. “There’s technological innovation for that. It is feasible, but it charges a little bit of vitality,” suggests Kim Ogden, who prospects a U.S. Department of Agriculture–funded exploration undertaking that is dependent at the University of Arizona and will work with various companion institutions, together with Bridgestone and Colorado State University. “So I’m not absolutely sure economically how excellent it is.”
Ogden and other scientists assume the actual moneymaker could be guayule resin. The sticky substance is created up of lots of natural compounds, which include necessary oils that could be made use of as fragrances and other molecules known as guayulins and argentatins that are unique to guayule. The researchers say the resin compounds hold assure for a range of probably lucrative works by using. Researchers at the College of Arizona uncovered the resin could be applied for plant-based mostly adhesives, potentially changing some formaldehyde-made up of solutions these types of as wood glue. A recent study also found that argentatin-derived compounds were harmful towards a few types of most cancers cells, opening the possibility for their use in drug investigation.
New Mexico Condition University’s Brewer sales opportunities a workforce that is tests regardless of whether the resin compounds could serve as insect repellents. She has created experiments comparing cockroaches’ responses to guayule resin extracts with their reactions to java oil (which is a recognised roach repellent) and acetone (which roaches never mind). Some of the resin compounds, including some unique to guayule, thwarted roaches even more than the java oil—“which we believed was rather exciting,” she says. The bugs appeared to dislike the scent of the resin, however extra investigation is desired to realize how this attainable repellent operates. Brewer is also starting an experiment with mosquitoes. She thinks a guayule resin extract would likely repel them, way too. But launching a topical purchaser merchandise requires a series of safety checks, and it is feasible that these compounds could result in allergies or irritate pores and skin.
“The resin has a huge combination of compounds, and what’s heading to identify how it’s applied is how much income it can take to individual it, relative to the worth of the products that you get,” Brewer says. “So there’s going to be some sweet location of just plenty of processing and purification, when compared to the makes use of, and we do not know the place that sweet place is yet.”
Though guayule has a means to go on the road to commercialization, the researchers associated are optimistic. Colorado Point out University’s Quinn prospects financial assessments for a lot of rising products and solutions and technologies—and he says only about a person in 10 finishes up seeming practical. “This,” he states, “is just one of those people.”
