Ontario Trees & Shrubs website

The Monday Garden
Oaks: Sudden Death

Issue No. 141 - December 12, 2004
by Sue Sweeney

  
It started in California, as many things do. And like so many things Californian, we, on the East Coast, think if we ignore them long enough, they'll go away. Seldom happens. Now, there's an advisory out from the Connecticut Department of Forestry of "a very troubling development".
 
Pictures: The young red oak in the vest pocket park at Hoyt and Prospect Streets in Stamford, CT, fall 2004
 
"Sudden Oak Death" is not a kind of baseball or poker. It's a stealthy serial killer of our great American oaks. Unless you look closely, the tree seems fine; but, then, suddenly, it wilts and dies in a month. However, the signs are there a year or two earlier-- inspect the trunk carefully for irregularities such as lesions or seeping sap. Sudden Oak Death was first recognized in the mid-1990's in coastal California when many oaks suddenly died for no known reason. Eventually, the culprit was identified as the fungus Phytophthora ramorum, a relative of the Phytophthora that causes the infamous potato blight. This Phytophthora is potentially even more dangerous because, unlike its kin which spread slowly by contact, Phytophthora ramorum spreads through the air, and so is capable of traveling hundreds of miles in a single storm.

Up until now, Sudden Oak Death has been thought to be localized in parts of California and Oregon. In these places, though, it has been found in several species, including the rhododendron-laurel and viburnum clans. Sadly, there is no known practical way to combat this disease once it gets into the forest. Most vulnerable to this disease, they say, are our majestic northern red oaks, to whom this issue is dedicated. (note: the red oaks are the ones with the pointy leaves and the striped bark).

 
Pictures: The towering red oak in the Hoyt Street Alley, Stamford, CT 2003-2004
 
Very sadly, Donald H. Smith, Jr., Director / State Forester, Connecticut Department of Forestry, 79 Elm Street, 6th Floor, Hartford, CT 06106, now writes these chilling words to which I have little to add:
"I received news today that the USDA Animal and Plant Health Inspection Service (APHIS) has confirmed the presence of Sudden Oak Death, Phytophthora ramorum (Pr), on 5 of 14 samples sent to their Maryland labs by the Connecticut Agricultural Experiment Station (CAES) for confirmation. Sudden Oak Death is now confirmed to have been imported into Connecticut on infected nursery stock, sold and planted in the environment.

"Here is what is known: Shipments of over 10,000 rhododendron plants came into Connecticut over the past year from a nursery in Oregon. APHIS notified CAES in late October that they had traced infected plants forward from that nursery to 53 outlets in Connecticut. CAES set about the process of visiting the outlets and taking samples for testing for Sudden Oak Death. Pathologist Sharon Douglas of the CAES conducted DNA analysis of pathogens found on numerous plants at numerous outlets and found multiple positive results. 14 samples of those positive tissues were sent to APHIS labs for confirmation. Yesterday (11/22/04) APHIS announced to CAES that 5 of the samples were confirmed positive for Sudden Oak Death. The 5 positive samples came from 3 sites in Connecticut.

"At this time, plant stock of host species at each of the 3 sites is being held and cannot be sold. APHIS and CAES are coordinating the response to this situation.

"What is the immediate impact on the forests of Connecticut? None - yet. What has happened is that the pathogen has been introduced into the Connecticut environment. What we all feared has happened and we now must wait and watch closely to see what happens. It is simply a matter of time before we are able to determine whether the climate, environment and local
species favor the survival of the pathogen in our state. The best we can hope for is that the pathogen cannot survive here and dies out.

" What can you do? Homeowners who purchased rhododendron plants within the past year should examine their plants, looking for circular fungal lesions on the leaves. They should report any suspicious leaf conditions to the CAES (see below). Do not discard the plants without consulting the CAES, first. Foresters, arborists, tree wardens and loggers should be aware of the condition of oak foliage in and around residential areas with rhododendron plantings. Unusual foliage lesions or sudden wilting and dying of oak should be immediately reported to the CAES (see below). Suspect trees should NOT be cut and transported, as doing so may spread the pathogen to new areas. "

For massive amounts of further information, go to the APHIS web site. The contact information for the Connecticut Agricultural Experiment Station is 123 Huntington St., P.O. Box 1106, New Haven, CT 06504-1106, Phone: 203-974-8497

 
Pictures: The young red oak in the vest pocket park at Hoyt and Prospect Streets, Stamford CT 2003-2004
 
Special thanks to Jane-Kerin Moffat of Greenwich Audubon and the Connecticut Master Gardeners for getting out the word.
  
From The Monday Garden. Copyright © by Sue Sweeney. Reproduced with permission. 

More articles from The Monday Garden

"The Monday Garden" is a FREE email publication published by Sue Sweeney. Visit The Monday Garden website