Environment : Natural Enemies Drying Up Portugal Cork Crop : Drought, neglect and disease have ravaged country’s cork oaks, which produce half the world’s output.

LISBON —  It may be only a question of time before wine lovers are unplugging the plastic--rather than the cork--from their favorite vintage, and the source of the problem is here in Portugal, where people and nature seem to be conspiring to endanger the country’s cork.

That’s important because Portugal typically produces more than half the world’s supply of the light, resilient stuff that stops wine bottles, soles shoes and insulates space rockets.

Up to 20% of the country’s cork oaks have been decimated by a deadly fungus, aided in its attacks by years of excessive bark stripping, neglect, poor forest management and prolonged drought, scientists say.

The country is fighting back with a save-the-trees campaign and European Community funds to encourage land owners to plant cork oaks. But it may be too little too late.

According to Prof. Helena Pereira at Lisbon’s Agronomy Institute, foresters first began reporting an abnormal number of cork-oak deaths in the 1980s. By 1990, an estimated 10% to 20% of the mighty trees had died of what Portugal’s media dubbed the “Cork Plague.”

“Nobody knew what was causing the deaths, and there was great alarm,” she said. “Now we know a fungus that attacks the roots is what is killing the trees. But we still haven’t made the second step of finding how to fight the disease.”

For now, all that can be done is to cut down diseased trees before they infect others. And Portugal’s Forestry Commission has distributed leaflets urging bark strippers to disinfect axes they use to peel off the self-regenerating cork bark and to avoid overstripping.

The killer they are trying to fight is phytophthora cinnamomi --a soil-carried fungus that has attacked avocados in Central America, seriously mauled Australia’s eucalyptus and over the last 80 years has reduced Portugal’s forests of sweet chestnuts--once a staple food--to about 1% of the national forest area.

Quercus suber , the cork oak, makes up 22% of Portugal’s forests and accounts for roughly half the world’s high-quality cork woods. Attempts to grow cork oaks elsewhere--in California, South America, Japan, Australia, South Africa and Russia--have failed so far because of the trees’ sensitivity to climate.

The cork oak, apart from being a stickler about the warm climate and sandy soil of its natural habitat, has been considered a hardy species for centuries. It was first used to stop wine urns in the 5th Century BC, and the regeneration of cork forests in Portugal mainly has been left to nature. But over the years, the tree’s natural resistance has been worn down.

“The cork oak is protected by law in Portugal, but it has had many enemies--natural, political and economic,” said Antonio Leite of the Forestry Commission.

In the 1930s, cereals planted among cork oaks under a self-sufficiency program ordered by Portugal’s rightist dictator Antonio de Oliveira Salazar robbed the trees of nourishment.

After a 1974 coup, democracy was restored, and Portugal briefly flirted with communism. Most cork plantations were merged into huge, collective farms and often fell into neglect. Bark, which replenishes itself in nine- or 10-year cycles, was stripped too frequently. Large herds of cattle, or even goats, grazed under the trees, trampling or eating the roots.

The result--an ecological imbalance--has left the trees vulnerable to disease, Leite said.

In the 1980s, when many forests were reprivatized, some owners opted to plant Iberia’s “green gold”--the fast-growing eucalyptus that produces a cash crop of pulp for paper manufacture after only a comparatively swift 10 years. By contrast, cork oaks produce their first mature harvest only after 43 years.

“Anybody who is thinking of planting cork oaks today is not planting them for himself but for his children or even his grandchildren,” said Ewan Rankin of Sociedade Nacional Corticeira, Portugal’s second-largest cork producing group, which has been in the vanguard of promoting new forestry methods.

Although nine-year cyclical fluctuations make trend-spotting difficult in cork production, government figures show that harvest figures have been edging downward since the mid-1970s. To make up for the shortfall and to supply its expanding industry of converting cork into other products, Portugal has been forced to import raw cork from Spain, Italy and other countries. The price of raw cork has increased from the equivalent of about 9 cents a pound in 1982 to about 50 cents a pound this year.

Rankin said action has already begun, particularly in central and southern Portugal, to uproot and burn diseased trees and plant new ones.

As news of the “cork plague” spread, U.S. bottlers were quick to blame it for causing a corky quality in wines--the condition in which a rotten or broken cork affects the taste and smell of the bottled contents. But wine and forestry experts have since agreed that the disease does not affect cork quality.

“The problem of corkiness in wine is being noticed more often, probably because wines nowadays have all the flaws taken out of them, and so people start recognizing corkiness as a problem,” says Peter Bright, enologist at Joao Pires, a leading wine company. “There is a disease, but that’s not causing corkiness.”

Bright noted that modern technology means plastics can be used to stop bottles effectively, at least if the wine is not kept for years before drinking. But he noted: “It’s largely a matter of prestige. Anybody who is paying a decent price for a wine wants to see a cork in the bottleneck.”

If unchecked, the fungus could cut production further and send cork prices higher, with frightening consequences for the industry. A government report on forestry economics warned last year that “any significant decrease in world cork production could prompt consumers to move, probably irreversibly, toward alternative products.”

As much as 30% of a $31-million forestation program funded by the European Community and the Portuguese government should find its way into cork oak farmers’ pockets over the next 10 years. The cash incentives are designed to persuade land owners to plant cork oak and tide them over until first harvests.

But, as Leite points out, funds need to be sunk into expensive genetic engineering projects to produce tougher trees and into training growers to tend their cork oaks better.

“The cork oak is a national monument,” he said. “If we don’t want to lose it, we must change our ways.”