Lurking in the Water: Surveying for Sudden Oak Death in North Carolina

One of the many majestic oak trees of North Carolina.

When we think of things that cause destruction to our forests, we envision fires, urbanization or maybe insects. However, in many cases the threat can’t be seen with the naked eye. Numerous micro-organisms, such as fungi or bacteria, can cause diseases that harm our trees. The harm is so great that the amount of timber lost yearly to micro-organisms is larger than all other causes combined.

In light of these virtually invisible threats, it comes as no surprise that we are especially cautious of any new, non-native diseases that could establish a presence in our forests — especially if that disease is known to be catastrophic and can kill numerous plant species. Sudden oak death is one of the top threats in North Carolina.

In northern California and parts of Oregon, sudden oak death has already caused the demise of countless oaks in the forest landscape. In a state whose capital is called “The City of Oaks” and plays host to such events as the New Year’s Eve Acorn Drop and the City of Oaks Marathon, the devastation would affect North Carolinians who enjoy and love the oak forests found throughout the state.

Sudden oak death is bit of a misnomer in two ways. First, it doesn’t just infect oak trees. The host list for sudden oak death is quite large, with more than 50 species, and includes rhododendrons, camellias, Pieris, mountain laurel, viburnum and lilacs. Not all host plants show symptoms of disease when infected; therefore the risk of the disease going unnoticed and perhaps moving to new areas is high. Second, affected plants do not die suddenly; rather, death occurs over a period of a few years. Because of this, it may be several years until the disease is noticed in a new area.

Sampling stream water for the presence of the pathogen that causes sudden oak death.

Sudden oak death can easily spread to new areas via streams and rivers, and it is possible that spores of the pathogen that causes sudden oak death are lurking in the waters of North Carolina. That is why the N.C. Forest Service is vigilantly searching for the pathogen in streams throughout the state to detect the pathogen before it causes similar destruction experienced in the western part of the country. For the past several years, the N.C. Forest Service has taken yearly samples of stream water to detect the presence of the sudden oak death pathogen. Efforts are currently under way to analyze the first of this year’s samples.

To date, the pathogen and the disease it causes have not been found in the forest ecosystems of North Carolina. We remain vigilant in our hunt for this disease, because in recent years, the pathogen has been found in several N.C. nurseries on plants shipped from the West Coast. While these plants were destroyed, there remains the chance that the pathogen escaped into our forests before infected plants were destroyed or that some infected shipments may have gone undetected.

It is important that we protect our forest lands and native trees.

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