Sudden Oak Death Syndrome, has devastated oak forests and the commercial plant nursery industry in northern California since it was first identified in 1995. Nursery-grown rhododendron plants that were shipped to Connecticut earlier this year from Oregon were infected with the organism that causes the disease.
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For now, forestry and agricultural officials are waiting to see if the organism, Phytophthora ramorum, which reproduces with spores, has escaped into the environment, and whether it can survive the Connecticut winter.
If so, experts at the U.S. Forest Service research center in Hamden and the Connecticut Agricultural Experiment Station in New Haven warn that it could cause severe ecological damage and cost homeowners and nurseries millions of dollars.
"If we do find it in trees, we would have to get into an eradication program," said Louis Magnarelli, chief scientist at the Agricultural Experiment Station. "Right now we're in the vigilance stage, and we'll have to see if anything develops."
"They don't know if it will take hold in the Northeast," said Rebecca Nisley, a communication specialist at the Forest Service experiment station in Hamden, speaking of scientists for the Forest Service who are also watching the situation closely. "The concern is that it will, because we have so many oak forests."
Magnarelli said the state estimates that 18 percent of the trees in Connecticut are oaks.
The disease is named for its effect on oaks, because it kills them more dramatically than it does other plants, but the organism is known to infect as many as 60 species of trees and shrubs, including mountain laurel.
An epidemic in Connecticut might prove especially poignant, because the white oak is the official state tree and the mountain laurel is the official state flower.
It actually takes about two years for the disease to kill a mature oak tree, but an infected tree typically appears healthy to the casual observer during most of that time.
The fungus causes trunk wounds called cankers that girdle a tree and kill it. Black or reddish ooze may drip from the cankers. In the final stage that takes only a few weeks and is the origin of the name of the disease, the leaves of the tree turn brown, and the tree dies.
"It's dramatic," said Magnarelli. Many shrubs, including rhododendron, are carriers of the disease but don't die, she said.
Such may also be the case with mountain laurel, but eradicating the disease may require the destruction of many infected mountain laurel bushes.
The red oak is the only oak species in the Northeast known to be threatened by Sudden Oak Death Syndrome, but in California it kills numerous oak species, so scientists believe that white oaks and black oaks in Connecticut may be susceptible.
Invasive species, pests and pathogens that evolved in one ecosystem and are then transported by human beings to another, can cause a great deal of commercial and ecological damage and even threaten human health.
The most notorious such pest in Connecticut has been the gypsy moth, native to China but accidentally released in Massachusetts in the 1800s. Trying to control it has cost property owners and taxpayers millions of dollars.
Elm and chestnut trees were devastated in the last century by blights. Once among the most common trees, neither elms nor chestnuts can be found anywhere in Connecticut anymore.
Scientists and agricultural officials are warily monitoring Connecticut's border with New York for evidence of the Asian longhorn beetle, and they are waging a spirited battle against the hemlock wooly adelgid that is sucking the life out of hemlock trees from Georgia to Maine.
The Forest Service experiment center in Hamden grows adelgids from infected hemlock branches and sics tiny Asian lady beetles on them trying to develop an effective natural way to control them.
Magnarelli said the Connecticut Agricultural Experiment Station has an elaborate statewide surveillance system to provide early warning of outbreaks of tree and shrub pests.
He said the state routinely monitors 153 plots across the state for signs of pests, conducts aerial surveys to spot defoliation, and receives reports from professional arborists.
If Sudden Oak Death Syndrome is suspected, Magnarelli said the Agricultural Experiment Station has tests kits that can determine whether P. ramorum is a possibility. Then a sample will be sent to a Forest Service lab in Maryland for a DNA analysis for confirmation.