The Role of Ambrosia and Bark Beetles in Sudden Oak Death

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Dulcie Gilmore
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1 The Role of Amrosi nd Brk Beetles in Sudden Ok Deth Brice A McPherson 1 Dvid L. Wood 1 Ndir Erilgin 1 Pvel Svihr 2 Andrew J. Storer 3 Richrd B. Stndiford 1 1 University of Cliforni Berkeley 2 University of Cliforni Coopertive Extension, Novto 3 Michign Technologicl University, Houghton

2 Beetle tunneling cn kill P. rmorum-infected cost live ok without evidence of decy fungi

3 The totl impct (infected + ded) of SOD on cost live oks in Mrin County incresed in every plot from 00 to Plot

4 00 Cost Live Ok 9% Asymptomtic Bleeding Ded 24% 03 Cost Live Ok Asymptomtic Bleeding Ded 24% 67% 18% 58% 06 Cost Live Ok Asymptomtic Bleeding Ded 31% 52% 17%

5 Cost live ok infection levels hve remined reltively stedy s mortlity hs incresed in Mrin County disese progression plots, 00 to 06. Infected trees re shown s percentges of living, nd ded s percentges of totl numers of trees Infected Ded Yer (Mrch)

6 The cumultive incidence of new infections nd mortlity mong cost live oks in Mrin County hs incresed stedily since Newly Symptomtic Newly ded Yer

7 Weiull regression nlysis found considerle differences in medin survivl of cost live oks in 4 different cohorts : Asymptomtic (1), Bleeding only (2), Bleeding with Beetles (3), nd Bleeding with Beetles nd Hypoxylon (4). Ctegory (disese sttus) Survivl (yers ± SE) 29.5 (8.4) 7 (1.2) 2.6 (0.3) 2.9 (0.3)

8 Helth nlysis: For oth cost live oks nd tnoks, stem dimeter (dh) predicts durtion in n symptomtic condition: s dh increses, proility of infection increses. Dh in 00 (cm) (ok) 70 (tnok) Cost live ok Tnok Weiull helth nlysis: Figs. nd re cost live ok in Chin Cmp nd MMWD, respectively; c is tnok. The green line defines the men for ech popultion.

9 Why re the roles of rk nd mrosi eetles of interest? Erly ttcks re only found within the mrgins of cnkers >95% of ded, infected trees were ttcked y eetles while live Beetle-ttcked live trees hve ccelerted rtes of structurl filure These eetles re not reported to ttck trees tht pper to e vigorous Beetle ttcks on infected trees pper to e significntly ssocited with decresed survivl

10 Experimentl design Cost live oks were inoculted with P. rmorum in July 02 Insecticide (0.2% Permethrin) ws pplied in August 02 nd Mrch & August 03 Sticky trps were plced on the insecticide-treted inoculted nd mock-inoculted (wounded) trees in Mrch 03 Insecticide No Insecticide Inoculted Wounded Control Inoculted Wounded Control 40 40

11 Inocultion study results 80% of inoculted trees developed leeding within 1 yer 97% of ll eetles were trpped on inoculted trees Insecticide delyed eetle ttcks for up to 2 months, ut did not prevent them Bleeding cnkers mesured 9 months fter inocultion rnged in size from m 2 to 1.13 m 2 7 sprotrophic eetle species were trpped: Monrthrum scutellre, M. dentigerum, Xyleorus clifornicus, Xyleorinus sxeseni, Gnthotrichus pilosus,pseudopityophthorus puipennis (rk eetle) (ll Cucurlionide, Scolitine), Scoici declivis (Bostrichide)

12 Totl Numer of Brk, Amrosi & Powderpost Beetles Trpped t Bleeding & Non-Bleeding Trees Men N Beetles (+/- SE)/Trp Bleeding Non-Bleeding April My June Octoer Novemer

13 Beetle ttcks on insecticide-treted trees were consistently lower thn on untreted trees. This hs not resulted in differentil mortlity (yet?). 25 No Permethrin Permethrin Months post-inocultion

14 Numers of eetle ttcks on permethrin-free trees in April predicted long-term disese sttus Bleeding + Beetles Bleeding + Beetles + Hypoxylon 15 Ded Months post-inocultion

15 Cnker size in April predicted long-term disese stge 0.8 c Bleed only Bleed + Beetles Bleed + Beetles + Hypoxylon Ded 0.6 c c c 0.4 c Months post-inocultion

16 Beetle trp ctch in April - efore ny of the permethrintreted trees hd een ttcked - predicted long-term disese stge c 40 Asymptomtic Bleeding Only c c Bleeding + Beetles Bleeding + Beetles + Hypoxylon Ded Months post-inocultion

17 Some conclusions nd specultions This pthogen continues to infect new trees nd spred within heterogeneous environments Simple extrpoltion from the pst 5 yers points to significnt mortlity in the ner future, ssuming tht nothing chnges significntly Newly Symptomtic Newly ded Yer 10

18 Some conclusions nd specultions The term resistnce my e difficult to define in terms of tree response to this pthogen. An infected cost live ok my e le to limit the extent of cnker expnsion, ut eetle ttcks, followed y fungl growth, my shift the lnce. Chrcteristiclly sprotrophic eetles re plying new roles in these environments y selectively ttcking cnkers on infected, ut pprently vigorous trees.

19 Acknowledgements Funding provided y US Forest Service, Pcific Southwest Reserch Sttion University of Cliforni Exotic/Invsive Pests Progrm University of Cliforni ANR Field nd l workers hve included (ut re not limited to) Dn Strk Griel Ritok-Owens Andrew Nelson Nicole Plkovsky Kim Kiernn Access nd ssistnce provided y personnel from Chin Cmp Stte Prk nd Mrin Municipl Wter District

FINAL REPORT YEAR 3/3

FINAL REPORT YEAR 3/3 WTFRC Project # PR-4-435 WSU Project # 13C-3661-8367 Project title: Phcidiopycnis Rot of Pers PI: Chng-Lin Xio, Assistnt Plnt Pthologist Orgniztion: WSU-TFREC, 11 N. Western Avenue,