Persistence of Phytophthora
        kernoviae and P. ramorum on
      infested sites: impact on disease
                ma...
P. kernoviae / P. ramorum
Both apparently introduced invasives in Britain
Both aerial Phytophthoras which cause foliar/sho...
Disease outbreaks: 2002/03 - 08
             England, Scotland and Wales

  Pathogen             Nurseries/ retail        ...
XXXXXX

     Distribution of Pr    Distribution of Pk


XX
 XX




                          XXXXXX
Current measures in the UK
• EU emergency measures apply to Pr
  – eradication of infection in nurseries
  – containment/e...
Impact of rhododendron eradication
           over 1-3 years
• Time frame for persistence in naturally
  infected leaves o...
How long does
inoculum persist?
Persistence of Pk
     inoculum




Naturally infected leaves put into bags
and air suspended or put in litter layer
Survival of Pk in naturally infected leaves:
                                2005 - 06

                                 A...
Deterioration of leaves over in the litter layer




3 months                 9 months




 6 months                12 mon...
Survival of Pk in naturally infected leaves:
                 2006 - 07
                             Air exposed          ...
Survival of Phytophthora in naturally
     infected leaves: 2006 - 07
             45
                              P. ker...
Survival of Pr in naturally infected leaves:
                   2006 - 07

                           100
% leaves with P....
Pre and post R. ponticum removal in a Pk
           infested woodland
                                80
                 ...
What happens to inoculum………

                         ◄ Re-sprouting from
                         rhododendron stumps wit...
Seedling Foliage   Soil   Roots
1
2
                                  Impact of persistent Pk inoculum
3
4
               ...
Conclusions
• Both Pr and Pk are proving to be difficult to
  eradicate from infected natural or semi- natural
  environme...
O26 Webber
O26 Webber
Upcoming SlideShare
Loading in...5
×

O26 Webber

615

Published on

2008 Phytophthora Workshop in Italy

Published in: Technology, Business
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
615
On Slideshare
0
From Embeds
0
Number of Embeds
1
Actions
Shares
0
Downloads
8
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

O26 Webber

  1. 1. Persistence of Phytophthora kernoviae and P. ramorum on infested sites: impact on disease management Joan Webber, Forest Research 3rd International Phytophthora Workshop
  2. 2. P. kernoviae / P. ramorum Both apparently introduced invasives in Britain Both aerial Phytophthoras which cause foliar/shoot symptoms on rhododendron Rhododendron is the UK ‘bay laurel’ Both cause bleeding lesions on trees, mainly beech (Fagus sylvatica) Both thrive under similar climatic regimes typical of Cornwall in south west England, so the majority of outbreaks are there
  3. 3. Disease outbreaks: 2002/03 - 08 England, Scotland and Wales Pathogen Nurseries/ retail Managed/ plant sales unmanaged P. ramorum 611 (498*) 224 (68*) P. kernoviae 4 (3*) 55 (2*) Total 615 (501*) 279 (70*) * eradicated outbreaks Data derived from Defra Consultation document 2008
  4. 4. XXXXXX Distribution of Pr Distribution of Pk XX XX XXXXXX
  5. 5. Current measures in the UK • EU emergency measures apply to Pr – eradication of infection in nurseries – containment/eradication of infection in natural and semi-natural environments • Similar measures apply to Pk – containment or eradication via the removal of infected understorey plants as the majority of outbreaks are in woodlands with a dense understorey of R. ponticum
  6. 6. Impact of rhododendron eradication over 1-3 years • Time frame for persistence in naturally infected leaves of rhododendron? • Persistence in litter and soil? • Regrowth and re-infection of the rhododendron?
  7. 7. How long does inoculum persist?
  8. 8. Persistence of Pk inoculum Naturally infected leaves put into bags and air suspended or put in litter layer
  9. 9. Survival of Pk in naturally infected leaves: 2005 - 06 Air exposed Litter embedded 100 90 80 % leaves with Pk 70 60 50 40 30 20 10 0 0 1 2 3 4 5 6 8 12 Month
  10. 10. Deterioration of leaves over in the litter layer 3 months 9 months 6 months 12 months
  11. 11. Survival of Pk in naturally infected leaves: 2006 - 07 Air exposed Litter embedded 100 90 80 % leaves with Pk 70 60 50 40 30 20 10 0 0 1 2 3 4 6 8 10 12 Months
  12. 12. Survival of Phytophthora in naturally infected leaves: 2006 - 07 45 P. kernoviae P. citricola 40 35 30 % recovery 25 20 15 10 5 0 0 1 2 3 4 6 8 10 Months
  13. 13. Survival of Pr in naturally infected leaves: 2006 - 07 100 % leaves with P. ramorum 90 Air exposed Litter embedded 80 70 60 50 40 30 20 10 0 0 1 2 3 4 6 8 10 12 Months
  14. 14. Pre and post R. ponticum removal in a Pk infested woodland 80 Litter Soil Percent Pk positive samples 70 60 50 40 30 20 10 0 Pre-treatment Post-treatment Post-treatment (Sept '04) (Sept '05) (Sept ’07)
  15. 15. What happens to inoculum……… ◄ Re-sprouting from rhododendron stumps with infection Recruitment of new ► rhododendron seedlings
  16. 16. Seedling Foliage Soil Roots 1 2 Impact of persistent Pk inoculum 3 4 on rhododendron recruitment 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Fichtner et al., 2008: APS
  17. 17. Conclusions • Both Pr and Pk are proving to be difficult to eradicate from infected natural or semi- natural environments – eradication process must involve litter removal – but persistence is extended and signs of disease by Pk return after more than 3 yr following eradication – additional issue of asymptomatic infection of rhododendron roots by Pk • Is it worthwhile? – removing the infected rhododendron does safeguard trees in woodlands from Pk infection – reduces inoculum and therefore likely to reduce the opportunities for Pk to get into the nursery trade – consultation on ‘is it worthwhile’? www.defra.gov.uk/corporate/consult/phytophthora-ram- kern/index.htm
  1. A particular slide catching your eye?

    Clipping is a handy way to collect important slides you want to go back to later.

×