Skip to page content
USDA Forest Service
  
Treesearch

Research & Development Treesearch

 
Treesearch Home
About Treesearch
Contact Us
Research & Development
Forest Products Lab
International Institute of Tropical Forestry
Northern
Pacific Northwest
Pacific Southwest
Rocky Mountain
Southern Research Station
Help
 

Science.gov - We Participate


USA.gov  Government Made Easy


Global Forest Information Service

US Forest Service
P.O. Box 96090
Washington, D.C.
20090-6090

(202) 205-8333

You are here: Home / Search / Publication Information
Bookmark and Share

Publication Information

View PDF (13.0 KB bytes)

Title: Root sssociations of Phytophthora ramorum and Phytophthora kernoviae in U.K. woodlands

Author: Fichtner, Elizabeth; Rizzo, David; Kirk, Susan; Whybrow, A.; Webber., J.;

Date: 2009

Source: In: Goheen, E.M.; Frankel, S.J., tech. coords. Proceedings of the fourth meeting of the International Union of Forest Research Organizations (IUFRO) Working Party S07.02.09: Phytophthoras in forests and natural ecosystems. Gen. Tech. Rep. PSW-GTR-221. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station: 281

Publication Series: General Technical Report (GTR)

   Note: This article is part of a larger document. View the larger document

Description:

Phytophthora kernoviae and Phytophthora ramorum, two pathogens recently introduced to the U.K., incite foliar lesions, shoot necrosis, and death of Rhododendron ponticum, an invasive weed pervading U.K. woodlands. In infested woodlands, R. ponticum serves as an epidemiologically important host, supporting sporulation of both pathogens. Bleeding cankers on trunks of European beech (Fagus sylvatica) caused by either P. ramorum or P. kernoviae are often associated with neighboring infected R. ponticum.

Rhododendron ponticum has been removed from several woodlands as an inoculum management strategy, but the long-term efficacy of plant removal is unknown, in part due to lack of knowledge of pathogen persistence in roots and in emerging seedlings.

The potential for P. ramorum and P. kernoviae to infect roots of R. ponticum in U.K. woodlands is unknown. To assess pathogen association with rhododendron roots, roots initiated from natural layering were excavated from two sites infested with P. kernoviae and one site infested with P. ramorum. At each site, four sets of layered roots were sampled, in addition to the associated leaf litter, rhizosphere soil, and symptomatic leaves. In the laboratory, soil and leaf litter were individually baited using leaf disks of Rhododendron catawbiense ‘Cunninghams White.’ Tissue from symptomatic leaves was embedded in SMA agar for isolation of Phytophthora spp. Neither pathogen was baited from rhizosphere soil, but both were routinely recovered from leaf litter. Phytophthora ramorum was baited from one set of layered roots; P. kernoviae was baited from three sets of roots at one site and from two sets at another site.

A second objective focused on investigating the potential for infection of R. ponticum seedlings in a woodland cleared of R. ponticum in 2005 for management of P. kernoviae. Nineteen seedlings were excavated from the woodland and all foliar lesions were sampled for pathogen isolation. Rhizosphere soil and roots were independently baited with rhododendron leaf disks. Phytophthora kernoviae was recovered from foliar tissue on 2 seedlings, from roots of 5 seedlings, and from two samples of rhizosphere soil.

The results suggest that both P. ramorum and P. kernoviae are associated with R. ponticum roots in infested U.K. woodlands. Furthermore, the presence of inoculum in litter but rarely in soil suggests that the pathogens may infect the roots, rather than simply persist on the rhizoplane. Further research is needed to assess the frequency of root associations and to histologically visualize root infections of thesetwo pathogens. These preliminary data suggest that the potential persistence of these pathogens in roots and litter should be considered when managing the diseases in infested woodlands.

Publication Notes:

  • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
  • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.

XML: View XML

Citation:


Fichtner; Elizabeth; Rizzo, David M.; Kirk, Susan A.; Whybrow, A.; Webber, J. 2009. Root sssociations of Phytophthora ramorum and Phytophthora kernoviae in U.K. woodlands. In: Goheen, E.M.; Frankel, S.J., tech. coords. Proceedings of the fourth meeting of the International Union of Forest Research Organizations (IUFRO) Working Party S07.02.09: Phytophthoras in forests and natural ecosystems. Gen. Tech. Rep. PSW-GTR-221. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station: 281.

 


 [ Get Acrobat ]  Get the latest version of the Adobe Acrobat reader or Acrobat Reader for Windows with Search and Accessibility

USDA logo which links to the department's national site. Forest Service logo which links to the agency's national site.