BY RACHEL WEHR
If you’re from Pima County, Arizona, you may not be familiar with the tree that produces the much-loved oil that garnishes your caprese salad, hummus or artisanal pizza. And there’s a reason why.
Since the mid-1980s, it has been illegal to plant olive trees in Pima County because they are thought to aggravate allergies.
But a number of other Arizona counties have caught onto the trees’ affinity for Arizona’s semi-arid climate, with its rainy winters and long, hot summers. Large olive orchards have popped up throughout the state. Several of them are on native lands.
Olives in our backyard
In the 17th century, Spanish missionaries brought olive tree cuttings to what later would become Arizona. In 1890 the University of Arizona campus was but one building surrounded by a scattering of creosote bushes, cactuses and one unexpected botanical: olive trees.
Today, if you stroll down James E. Roger Way on the UA campus, you’ll find yourself surrounded by the thick canopy of these old trees. Their gnarled trunks reach in all directions, a work of art all their own. In the fall the trees produce a bounty of plump, dark fruits.
These trees have a rich history. In the 1890s Robert Forbes, one of first faculty members in the College of Agriculture, planted most of the olives tree alive on campus today.
“Everything else Forbes touched was gold,” said Tanya Quist, director of the UA Campus Arboretum. “He was responsible for the development of the citrus industry, dates, cotton, all sorts of forage grasses and many other crop plants.”
“So I wonder, why not olives?” Quist said.
“I think that they’re really valuable because they’re an important part of our university’s heritage,” Quist said. “They reflect our ongoing commitment to our land grant mission, which is to test and try things that will then be introduced out into the state to boost economic growth.”
Little is known about Forbes’ endeavor to grow olives throughout the state in the early 20th century. According to his biography, The Century of Robert H. Forbes, the Casa Grande Valley offered the environmental and economic conditions ideal to launch an olive industry. Forbes recommended that farmers in the area plant 10-acre groves, which could then expand.
So why did the industry never develop?
Forbes didn’t foresee that competition from cheap imported olive oil would kill the American olive market, according to his biography.
More recently, olive trees have been grown from cuttings at Tucson’s Mission Garden. The site received a special permit to plant the trees because of its status as a heritage garden, according to Dena Cowan, the garden’s manager. “The varieties at Mission Garden are Manzanilla and Mission olives,” Cowan said.
It’s not clear if other trees planted in Tucson before the ban are descended from the original campus trees.
*** INFOGRAPHIC – Olive Oil Production
Ban on olive trees
Olive trees yield fruit with about 35 inches of water per year, according to the University of California Division of Agriculture and Natural Resources. Subtract the 12 inches of precipitation that Tucson receives each year, and the olive trees would need an additional 23 inches of water per year. This is a relatively low amount of water for maximum fruit production. By comparison, a mature lemon tree needs 60 inches of water per year.
Arizona lacks native pests and diseases that plague the olive tree, such as the olive fly, which can’t survive in hot temperatures, according to the Yuma County Cooperative Extension. There is very limited exposure to olive knot, a bacterial disease caused by Pseadomonas savastanoi, according to the Queen Creek Olive Mill.
In 1984 the Pima County Board of Supervisors banned the planting of Bermuda grass, mulberry trees and olive trees. This law stemmed from concerns that pollen from the grass and trees might exacerbate allergies, asthma and other respiratory conditions.
Whether the olive trees’ pollen is a concern outside of urban areas isn’t clear. The pollen is heavy, but it may only be a concern near the tree.
When planted in an urban area, the trees are also messy. “Less people complain about the pollen than complain about the sidewalk mess,” Quist said.
For several years the Linking Edible Arizona Forests on the UA Campus group (UA LEAF) harvested olives from the campus trees and sent them to the Queen Creek Olive Mill to be turned into olive oil. Harvesting reduces fruit drop onto paved areas surrounding the trees.
Today only a few varieties, such as Swan Hill and Wilson’s Fruitless, are legal to plant in Pima County. They produce very little pollen and are nearly fruitless.
Times are a changin’
More than 1,200 acres of olives grow in the deserts of Arizona and California, with large-scale plantings from Yuma County to the Imperial Valley. California produces less than 5 percent of the world’s olive crop, and Arizona even less, according to the Yuma County Cooperative Extension.
Most olives and olive oil consumed in the United States are produced in Italy, Spain and North Africa. Olive growers in the European Union are subsidized so highly that the price of a bottle of olive oil shipped across the Atlantic Ocean is less than one produced in-state, according to Glenn Wright, an extension horticulturist with the UA School of Plant Sciences.
Only 500 acres of olives grow in Arizona, all planted in the last five years, Wright said.
In order to make olive plantings lucrative, there’s one specific requirement. “You’ve got to have relatively inexpensive land,” Wright said. “In Yuma you want to put something on your land with higher value, like lettuce.”
A movement is catching on in Arizona to plant on native lands. “The most important specific reason is that the water is free,” Wright said.
Gila River Farms, a part of the Gila River Indian Community, planted 300 acres of olives in October 2015. The San Carlos Apache Indian Reservation will also be planting olive trees in the next few months, Wright said.
“This is potentially a new market that will really help underserved populations in Arizona have more of an economic base,” Quist said.
The most popular grower in Arizona may well be the Queen Creek Olive Mill in Maricopa County. The farm and mill dedicate more than 100 acres to growing olives for oil production. At the moment Queen Creek is the only olive mill in the state, so growers from as far as Yuma ship their olives there to be processed and distributed.
Given the popularity of local food movements, perhaps the Arizona olive oil industry will grow enough to make money and fulfill the dream of Robert Forbes a century ago.