Plant disease threatens traditions of California tribes
Mary Larson Bishop gazes at the folds and peaks of the Santa Lucia Range with longing. "I used to go deep into the woods looking for herbs," says the Salinan tribal elder, who is known for her knowledge of medicinal plants such as yerba santa, traditionally used to heal skin inflammation. Now, she no longer roams the Central California coastal hills. "I'm afraid of bringing anything out of the woods that might spread to other trees," says Bishop. "I don't want to track that crud out of the hills."
The "crud" is Phytophthora ramorum, a minuscule waterborne mold that weakens and kills many species of native trees and plants. The pathogen, which causes both Sudden Oak Death and Ramorum blight, was first discovered in the mid-1990s. Since then, it has spread to 14 California counties along the Pacific Coast, and even to Washington and Oregon. It travels by clinging to boots, hands, pant legs and tires.
The mold enters through the bark of a plant and literally eats its victim from the inside out, making it hard to diagnose until leaves start turning brown. It damages the twigs and leaves of more than 25 plants that tribes use for basketry, medicine and ceremonial purposes, including California bay laurel, maidenhair fern, madrone, Douglas fir, and coast redwood. The disease also attacks oaks, including tanoak, coast live oak, California black oak, Shreve oak and canyon live oak. A total of at least 250,000 acres of oaks have already died.
Many California and southern Oregon tribes, including the Salinan, Hoopa, Yurok and Karuk, have long relied on oaks for food as well as for cultural practices ranging from basketry to land management. "The overarching concern is for the oaks, since they are such an important plant for both humans and for wildlife," says Jennifer Kalt, a botanist with the California Indian Basketweavers' Association. The disease has disrupted coastal ecosystems and inconvenienced outdoor recreationists. But for the more than 30 coastal tribes known collectively as the Acorn Peoples, even more is at stake -- thousands of years of cultural practices and tradition.
Tribal members "come back to the same spot every year to gather acorns from the tanoak," says Nolan Colegrove, the Hoopa Tribe's senior forestry manager. Although the tribe's own land is not yet affected, P. ramorum has wiped out entire tanoak forests on public land that once served not only for food gathering, but for storytelling, instruction and ceremonies. If the mold continues to kill off oaks and interrupt plant-gathering cycles, elders could lose the chance to pass their knowledge to the next generation.
Some tribal members also worry about the mold's impacts on human health. "I have heard basketweavers ask scientists if ingesting the pathogen can be harmful, since they use their teeth for weaving and of course eat the acorns, and I have never heard anyone answer that question," says Kalt. So far, researchers have found no health problems caused by handling or ingesting the mold, according to Katie Palmieri, spokeswoman for the California Oak Mortality Task Force, although scientists still have much to learn about the pathogen.
To help control the spread of P. ramorum, which proliferates in cool, moist conditions, tribal members try to stay out of the forests during the rainy season, although that's the best time to gather many plants. Even in the dry summertime, stringent protocols instituted by tribal, state and federal land-management agencies must be followed in quarantined areas. Traditional gatherers and foresters alike have to wash soil and plant matter off their vehicles, equipment, clothing, and footwear with bleach before leaving the woods. Firewood, forest products and commercial nursery plants from quarantined areas must be certified pathogen-free. Outside quarantined areas, plants for basketry or medicine can still be taken, but gatherers are asked to dry the plants as soon as possible, burn unused parts such as bark, and boil any soaking water before pouring it out. Once a plant is infected, fungicides are ineffective. A chemical called Agri-Fos can help healthy plants resist the disease, but at the cost of making the plants and their products toxic to humans.
The Hoopa and Yurok tribes are participating in a study that monitors the spread of the mold. "It's just a matter of time," says Colegrove, before P. ramorum invades Hoopa lands. "And it's not like we can go anywhere else." Tribes believe that for spiritual and cultural reasons, their ceremonies and dances must be practiced within certain sites on their traditional lands -- sites that could become quarantined due to P. ramorum infection.
In the meantime, the tribes are considering a traditional forest-management tool to combat the microscopic menace. For thousands of years, Indians used fire to clear brush and stimulate growth of beneficial species such as native grasses, and some think fire could help control the disease. So far, however, the use of controlled burns is still under discussion.
But the California tribes remain hopeful. Bishop says, "My youngest daughter, Michelle Irvine, goes into the woods when the trees drop their acorns and brings them home." Irvine is sprouting the acorns and replanting seedlings across the Central Coast. "I have a beautiful red oak that she grew from an acorn; it is a very healthy tree," says Bishop. "I am hoping that someone will find a cure for this disease."
The author is a Salinan/Esselen Indian journalist based in Phoenix, Arizona.
This story was funded by a grant from the David and Lucile Packard Foundation.