Establish relationship between field mortality and Phytophthora cinnamomi

Transcription

1 Establish relationship between field mortality and Phytophthora cinnamomi

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3 Completion of Koch s Postulates in the laboratory Step 1: P. cinnamomi baited from soil Step 2: Isolate P. cinnamomi from roots P. cinnamomi isolated and baited from roots. All naturally-infected roots were surface sterilized.

4 P. cinnamomi in pure culture Identify P. cinnamomi by chlamydospore and sporangia morphology

5 Sporangia production: young hyphae nutrient depletion

6 Uninoculated Control P. cinnamomi--inoculated Pacific Madrone (Arbutus menziesii)

7 Wilting leads to mortality

8 Uninoculated Control P. cinnamomi--inoculated California bay laurel (Umbellularia californica)

9 Baiting for Phytophthora species Rhododendron leaves were floated outside pots as baits. Determine whether P. cinnamomi zoospores were released Determine presence of other Phytophthora species Uninoculated Inoculated

10 Pacific madrone Phytophthora cactorum Known canker pathogen on madrone in NW * Not a new pathogen * Old pathogen on new plant part ROOTS. Pacific madrone and bay laurel Pythium sterilum Isolated from bay laurel roots First isolated in 2001 in Spain from soil associated with declining Quercus stand. Since 2003, associated with root disease on declining oaks in Europe. Potential root disease of bay laurel in CA?

11 Phytophthoras: nursery-reared madrone Species From Pathogenicity P. cinnamomi roots, soil, leaves Root rot, wilting, mortality P. cambivora roots, soil Infects roots; asymptomatic P. cactorum roots, soil, Infects roots; asymptomatic P. gonapodioides soil? P. pseudosyringae soil? P. cryptogea soil? P. nicotianae soil? P. syringae stem **disease on Arbutus in Spain P. ramorum: infects roots; asymptomatic

12 Naturally-infected with P. syringae Implication for forest disease in CA?

13 Phytophthoras: nursery-reared madrone * 8 plant pathogenic Phytophthora species found in approximately 16 plants Highest frequency of recovery: P. cactorum P. cambivora P. cinnamomi Diagnostics: P. cactorum: structures formed in culture P. cambivora: difficult to identify in culture, heterothallic, no chlamydospores, sporangia ( song and dance to produce) P. cinnamomi: clusters of chlamydospores in culture. P. cactorum

14 Nevada City, CA Symptoms of root rot: wilting, whole tree decline. One individual symptomatic for Phytophthora; however, have not isolated the pathogen. A curiosity due to land-use history..but area severely affected by another disease.

15 Pacific Madrone Decline First noticed in WA and BC in 1976 after a serious drought Found in both urban and natural areas Most severe symptoms on exposed sites

16 Symptoms Cankers Branch dieback Shoot blight

17 Fusicoccum arbuti and Fusicoccum dimidiatum Originally identified as Natrassia mangiferae but later found to be Fusicoccum species Isolated from cankers, shoot blight Sexual stage in Botryosphaeria Other Botryosphaeria/Fusicoccum species cause similar symptoms on their hosts

18 Disease severity surveys Southern range CA04 Monterey Co, CA Northern range WA03 King Co, WA

19 Pycnidia exude asexual conidia Fusicoccum arbuti (Farr et al. 2005) Wounding creates infection court sun scald, draught, mechanical damage.

20 Fall 2008 Nevada City case study

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23 Mechanical injury from pine removal? Additional sunscald?

24 Healthy neighboring trees. Potentially lacked infection court. Protection in understory?

25 Summary 1. P. cinnamomi = emerging pathogen in CA forests. 2. Fusicoccum- ongoing problem; potentially severe due to recent drought year. 3. Nursery-grown madrone may be infected/infested with multiple Phytophthora species, thereby impeding efficacy of restoration programs.

26 Acknowledgements PHYTOPHTHORA COMPONENT Dave Rizzo, H. Mehl, A. Brauer, A. Oguchi: UC Davis Ted Swiecki and Liz Bernhardt: Phytosphere Research Elaine Fok: UC Berkeley FUSICOCCUM COMPONENT Marianne Elliot, University of Washington Tom Smith, CA Dept of Forestry and Fire Protection Kathleen Edwards, CA Dept of Forestry and Fire Protection FUNDING NSF- Research Experience for Undergraduates