Twenty years ago, scientists at the University of Arizona began studying guayule, a small desert shrub farmed as a source of natural rubber.

The research helped one Arizona company commercialize guayule on a limited scale, producing a virtually allergy-free latex used in medical gloves.

Now, the UA is studying guayule - pronounced "why-YOU-lee") - again as the plant is poised for wide-scale commercialization, and tire makers and others look to address a projected shortage of natural rubber.

The UA recently was awarded a $3 million, five-year grant by Phoenix-based Yulex Corp. focused on breeding and developing guayule for the production of "biorubber" for medical, consumer and industrial applications.

While the UA has worked on guayule research mainly through federally funded research grants, the Yulex contract is the first from the company and signals a trend toward advanced commercialization of guayule, said Dennis Ray, a distinguished professor in the UA School of Plant Sciences.

"We always thought this would become an industry, and it has," said Ray, who has been working on guayule research on and off since he arrived at the UA in the mid-1980s.

Leading a reporter through a small plot of guayule bushes at the UA agriculture center west of Interstate 10 near Miracle Mile, Ray rattles off the advantages of the scruffy-looking shrub.

Guayule thrives in arid climates, so it doesn't need much water, and it doesn't compete with food or fiber crops, he said. The latex produced in guayule's bark doesn't contain the proteins that makes people allergic to common natural latex, which is made from the tropical hevea tree. And it produces other useful compounds, including pest-resistant resins.

During the Yulex project, the UA researchers will initially work to isolate guayule strains that will make the plant more productive.

"We want to make more rubber, sooner," Ray said.

While Yulex already has begun providing guayule-based latex for some products, the UA's breeding program will be instrumental in helping the company ramp up production for bigger markets, Yulex CEO Jeff Martin said.

"There's never been a very all-inclusive breeding program in place of this scope, really in the history of guayule," Martin said.

Yulex has been producing latex from guayule since last year at a plant in Chandler, using raw plant material from farms in Marana and scattered around the state.

The plant has produced latex for use in medical gloves marketed by Australia-based Ansell Ltd., a major provider of medical and industrial gloves and condoms that acquired a minority stake in Yulex in 2011. Yulex also has provided biorubber for outdoor apparel giant Patagonia, which has created guayule-rubber-based wet suits set to roll out in the U.S. this fall.

The main selling point for the guayule rubber so far has been its nonallergenic nature - a trait that prompted Martin to quit his job at a major latex-glove maker to pursue guayule and co-found Yulex in 1997.

But guayule biorubber can be used in any application where the traditional source of natural rubber - the tropical hevea tree - has long dominated.

Guayule rubber isn't new - production was briefly ramped up in the U.S. during World War II, after Japan took over much of the world's rubber-producing region. The energy crisis of the late 1970s led to a resurgence in guayule research, but the plant never gained the traction to become a major industrial crop.

Now, major tire makers have stepped up research on guayule rubber. Bridgestone Corp. broke ground on a guayule biorubber process research center in Mesa in mid-May, and the company expects its first rubber samples for tire evaluations by mid-2015. Cooper Tire is partner with Yulex on a $6.9 million federal grant issued last year to study guayule rubber processing and use of byproducts as a biofuel.

Natural rubber is used in tires in varying amounts, but it's a commodity that is prone to big price swings.

"It is a material that is essential for use in tires, but it is a wildly price-sensitive commodity," said Chuck Yurkovich, Cooper Tire's vice president of global technology.

It will be awhile until Yulex can satisfy the tire industry's needs.

Martin noted that Yulex's production capacity of some 500 metric tons of biorubber annually is a tiny fraction of the world market of about 25 million metric tons.

"Even though it's commercial scale, it's still very small," he said.

Plans are afoot to expand that production exponentially.

Yulex has licensed the technology to Versalis, a major European chemical company, which plans to build a processing plant in southern Europe with a production capacity of 5,000 metric tons a year, Martin said. And talks are underway with undisclosed parties to build a 50,000-metric-ton plant, he added.

All that production will be needed particularly if the biggest rubber users - including the tire industry - jump into guayule in a big way.

With the UA's help, Yulex expects to boost its yield to about 1 metric ton per acre per year, about the same as hevea rubber-tree production. Current plantings yield about 50 percent to 75 percent of that goal, Martin said.

Ray said he's looking to use traditional plant-breeding techniques to boost the rubber content of guayule from about 8 percent now to a range of 10 to 15 percent.

Martin and Ray noted that guayule is a perennial plant that is ready for initial cutting in two years. The roots are left to regrow, and each plant can be cut three more times, giving farmers four harvests every five years.

Cooper's Yurkovich noted that other companies are working to commercialize guayule, but Yulex has a good head start.

And while the industry isn't facing a natural-rubber shortage now, some analysts predict a global shortfall by 2020 as China and other developing nations buy more cars.

"Big picture: The amount of natural rubber is declining, and the demand is going up," Yurkovich said.

Contact Assistant Business Editor David Wichner at or 573-4181.