From: Robin Blackstone, ENN
Published December 2, 2013 03:50 PM

Another rotten Grinch tale

Seemingly working in concert with the Grinch, Phytophthora root rot is taking hold in the roots of Christmas tree farms throughout Oregon and North Carolina. Phytophthora root rot is a rapidly moving fungus found in poorly drained soils. It causes a slow decline in a tree first destroying the feeder roots and then turning the needles light green or yellow. The pathogen infects the root cortex first depriving the remainder of the root and the plant from its nutrients. Pytophthora root rot is difficult to detect and is only verified with laboratory analysis.

With a $1.3 million grant from the U.S. Department of Agriculture National Institute of Food and Agriculture, Washington State University and North Carolina State University have been conducting research on the invasive soil borne fungus.



"Phytophthora root rot plagues all regions where firs are grown as Christmas trees," said John Frampton, a Christmas tree geneticist at North Carolina State University in Raleigh and a collaborator on the project. There is no effective control for Phytophthora, so the best way to tackle the problem is to find resistant tree species.

"The Christmas tree industry has some big challenges," said WSU researcher Gary Chastagner. "We hope that this national project will bring together scientific expertise and techniques to address these two issues."

One study estimated the potential losses to Oregon's nursery and Christmas tree industries of up to $304 million a year if Phytophthora is not properly contained. Douglas and Noble fir are the dominant holiday tree species in the Pacific Northwest.

In North Carolina, nationally the No. 2 producer, it costs farmers up to $6 million a year, said Frampton.

Most Christmas tree species are susceptible to this condition; including all true firs, Douglas firs, spruce and eastern white pines.  Field identification of symptoms includes failure to thrive after planting, reddish-brown needles, or dieback. Root systems may exhibit decay or stunted feeder root networks. Low-lying and poorly drained areas are at particular risk.  There is no known remediation available for this disease so replanting the area is for naught.

Katie McKeever, a Ph.D. candidate in Chastagner's lab, is working under a U.S. Department of Agriculture grant to create a nationwide collection of Christmas tree Phytophthoras to understand regional variation in pathogen populations. The goal is to challenge various firs with different Phytophthoras to determine mechanisms of resistance and ultimately develop genetic markers to identify trees resistant to the disease, Chastagner said.

Read more at Washington State University.

Christmas tree farm image via Shutterstock.

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