At present, sudden oak death (SOD) is killing trees and shrubs in forests along the Pacific coast from far southern Oregon to Monterey County in California – a stretch of more than 400 miles.
However, numerous tree and shrub species native to forests in the East also are vulnerable to the pathogen. These include several oak trees (northern red, chestnut, white, and pin oaks), sugar maple, black walnut; and such shrubs as mountain laurel and rhododendrons.
While no infestations of SOD have been found in the wild in the East, the pathogen is already present in some nurseries and continues to be transported to disease-free parts of the Southeast in shipments of nursery plants – as described in my previous blog.
Nine eastern states monitor streams to detect the pathogen in water. These states are AL, FL, GA, MS, NC, NY, PA, SC, & TX. As of 2013, six states had detected the pathogen in a total of 11 streams and ponds; all were outside nurseries that had previously had infested plants. These positive streams were distributed as follows: AL-4; FL-1; GA-2; MS-1; NC-1; TX-2.
In 2014, only four states (instead of six) detected the SOD pathogen in at least one stream: AL-4; FL-1; MS-2; and NC-2. Two of these streams were new – one each in AL and FL.
One of the AL detections is in a stream associated with a nursery that had not previously been determined to have infested plants. Authorities plans to sample vegetation near this stream. In the past, once a stream had tested positive, it remained positive in all subsequent years. However, the testing methods are not perfect so some variation in findings can be expected.
Infested plants were found growing in the ground (outside a nursery) at three sites: one each at homes in CT and MA; and a commercial business site in LA. These searches were undertaken because officials knew that these residents or businesses had bought plants from an infested nursery in earlier years.
As noted in my previous blog, SOD has been detected in eight nurseries in the East: ME-1, NY-2, TX-1, VA-4). The TX nursery became infested by plants received from a California nursery. I am very concerned about the presence of the pathogen in four Virginia nurseries, because the Commonwealth falls in the geographic region thought to be most vulnerable to the pathogen [see risk maps in the SOD writeup at http://www.dontmovefirewood.org/gallery-of-pests or in Chapter 5 of Fading Forests III.