City leaders have reconfirmed their commitment to confront sudden oak death – the disease caused by a little-understood fungus that has killed tens of thousands of trees in Northern California.
Though sudden oak death in Berkeley has been limited to a handful of trees on the UC campus, City Council this week asked staff members to evaluate policies that would prevent spread of the killer fungus.
“We’re concerned that the city and its residents are not properly prepared,” said Barbara Gilbert, a staff member for Mayor Shirley Dean and co-author of council’s request.
City Parks Director Lisa Caronna, who oversees about 240 acres of Berkeley wildlands, said
The city already has measures in place that require people to properly dispose of tree cuttings and sterilize landscaping tools, as well as monitor for the fungus.
Unfortunately, there is little information about the relatively new tree disease, discovered in 1995, and hence there is little certainty about prevention techniques.
“As a city, we’re following the current thinking [on prevention], but because so much is unknown about it, there are questions,” Caronna said.
Scientists first came across sudden oak death in Marin County when more than 10,000 tanoak trees developed oozing cankers on their trunks and died soon afterwards.
Only last year did researchers identify the Marin blight as the product of a water mold fungus. Researches now say that, in addition to a variety of oak species as well as the madrone, the fungus can infect dozens of other plants including the bay laurel and rhododendrons, though these plants are unlikely to die from infestation. Instead, they provide a pathway for the fungus to reach other oak and madrone trees.
Sudden Oak Death has now been identified in tree stands from the Bay Area to southern Oregon, and in February Alameda County became one of 10 counties quarantined by the United States Department of Agriculture.
“In Berkeley, we’re lucky we caught it early,” said adjunct professor at UC Berkeley Matteo Garbelotto, one of the foremost researchers of the fungus.
Garbelotto explained that though there is no treatment for trees infected by sudden oak death, research has brought some success in containing the fungus.
“Until recently, people had no idea it was spreading through the soil. They also didn’t know about hosts,” Garbelotto said. These discoveries have allowed park and resource managers to prevent the blatant spread of the fungus, he explained.
This year Berkeley ended its policy of giving away chipped vegetation, from landscaping, to residents who use it as mulch in gardens. All chipped material is now hauled off by covered trucks to Stockton where it is composted, and the fungus, if present, is not likely to spread.
A more aggressive pruning policy, more selective fertilizing, and limiting irrigation are other measures currently under consideration by city officials.
“This seems to make sense from a scientific perspective,” said Garbelotto. “I’m supportive.”
With increasing funding and attention, Garbelotto’s research to better understand and prevent sudden oak death continues at Berkeley.