PROMOTION OF FERTILIZER IN OAK DISEASE WAR CALLED 'ILLEGAL'
By Mary Callahan, The Press Democrat
April 29, 2001


A Petaluma man is at the center of a debate over emerging sudden oak death syndrome research that shows promise but is not yet complete.

At the core of the conflict is the impulse to race to save Cali-fornia's oaks and a competing interest in taking time for additional analysis. There also are legal questions surrounding the use of a substance that isn't registered for use as a fungicide to defend trees against a fungus-caused scourge.

No cure has been found for sudden oak death, which has killed thousands of trees from Sonoma County to Big Sur and continues to spread to new species. But a fertilizer already used on everything from lawns to avocado trees
has substantially reduced the size of the bleeding cankers that appear on sick oaks, according to research released last month by UC Berkeley scientist Matteo Garbelotto.

Ralph Zingaro, a state-licensed pesticide adviser who participated in Garbelotto's research, advertises the fertilizer -- called phosphite -- as a safe, legitimate treatment. "A lot of people are unsure what to do for their oak trees because they've been told so many different things," he said. "But it works. It will help save trees."

Zingaro has come under scrutiny by the district attorney in Marin County, where he does much of his work. Prosecutors asked him to substantiate advertising claims for a phosphite capsule he distributes.

Others say he's breaking the law by promoting a substance not registered
as a fungicide to battle a fungus-based disease.

"It's illegal to use," said Susan Frankel, a U.S. Forest Service plant pathologist and head of the California Oak Mortality Task Force.

Marin County Agricultural Commissioner Stacy Carlsen said Zingaro's actions are premature because the research isn't complete. "I think to translate that into field applications is a long way off," he said.

Sudden oak death is caused by a fungus similar to the one that caused the potato famine in 19th century Ireland. Initially limited to a variety of oaks, it recently was found to affect bay laurel and madrone trees, as well as rhododendrons and California huckleberry.

Garbelotto announced in March that experiments with 90 potted oaks
infected with the still-unnamed fungus showed phosphite reduced the size of the trees' cankers by an average of 75 percent.

More research is under way. Among the questions Garbelotto and others still want answered are how best to apply the fertilizer and whether it aids large trees in a natural setting.

Some likened using phosphite now on diseased trees to prescribing unapproved drugs or unproven herbal remedies for sick patients.
Zingaro counters that it's more like feeding supplemental vitamins and minerals to someone who is ill.

"With anything it's best to use good science, instead of grabbing at straws," Sonoma County Agricultural Commissioner John Westoby said.

Commercially produced phosphite is legal to use, though somewhat difficult to obtain. The nearest distributor seems to be in Watsonville.

Still, Garbelotto said, until new tests are completed, he's generally reluctant to recommend people treat their trees with phosphite.

But there's an exception.

If the disease is caught early in an otherwise healthy, robust tree, "why not use this product as a fertilizer to indirectly help the tree fight off the disease?" That's the question Zingaro and the fertilizer's primary manufacturer are asking. Despite the controversy surrounding its use, they plan to continue promoting it.

Newspaper ads are in the works, according to Peter Alvitre, one of the owners of Biagro Western Sales, which is licensed to manufacture a phosphite formulation developed and patented at UC Riverside. "Trees are dying up there," Alvitre said from his office in Visalia. "We've got a product that is out there and ready to use."

Biagro has entered the fray in Marin County, in part because Zingaro holds an exclusive license to market its product in a patented injection capsule, making it possible to apply fertilizer directly into a tree.

Both concede Zingaro's promotion crossed the line into making pesticidal claims, but they're adamant they are not touting the substance as a fungicide. "It doesn't really work directly against the fungus," Zingaro said. "What it does is stimulate the tree."

But Frankel, while hopeful for funding to accelerate phosphite testing, said it sounded as if the fertilizer's promoters are "trying to wiggle around the fact of the matter" that it's being used for an unapproved purpose.

"It just needs a lot more testing," she said.

You can reach Staff Writer Mary Callahan at 521-5249;
e-mail mcallahan@pressdemocrat.com.