THOUSAND CANKERS THOUSAND CANKERS DISEASE of WALNUT: DISEASE of WALNUT:

STATUS in CALIFORNIASTATUS in CALIFORNIAJanine Janine HaseyHasey

UC Cooperative Extension, Sutter & Yuba cos.UC Cooperative Extension, Sutter & Yuba cos.

Steve SeyboldSteve SeyboldUSDA Forest Service, DavisUSDA Forest Service, Davis

THOUSAND CANKERSTHOUSAND CANKERS

InsectInsect--vectored disease on vectored disease on walnutwalnut

Walnut twig beetle carries Walnut twig beetle carries fungal spores which infect fungal spores which infect phloem around entrance phloem around entrance hole resulting in canker hole resulting in canker formationformation

The fungus The fungus GeosmithiaGeosmithia isolated from beetles, isolated from beetles, beetle galleries, and beetle galleries, and cankers cankers

Pending species name: Pending species name: G.G. morbidamorbida

ACKNOWLEDGEMENTS ACKNOWLEDGEMENTS

GeosmithiaGeosmithia confirmationsconfirmations–– Ned Ned TisseratTisserat, Colorado State University, Colorado State University–– Suzanne Latham & Kathy Suzanne Latham & Kathy KostaKosta, CDFA, CDFA–– Rick Rick BostockBostock & & ThemisThemis MichailidesMichailides, UCD , UCD

Walnut Twig Beetle

(Pityophthorus juglandis)

This is reportedly regarded as a minor

pest associated with twig dieback

(California)

Jim LaBonte – Oregon Dept Ag

SYMPTOMSSYMPTOMS

PresenterPresentation NotesHotdog size or larger

CALIFORNIA STATUSCALIFORNIA STATUS

DiseaseDisease first found in Yolo Co. in June, first found in Yolo Co. in June, 2008 & Solano Co. in July, 20082008 & Solano Co. in July, 2008

Since then, confirmed in:Since then, confirmed in:–– Alameda, Los Angeles, San Joaquin, San Luis Alameda, Los Angeles, San Joaquin, San Luis

Obispo, Sutter, and Tulare Cos.Obispo, Sutter, and Tulare Cos.–– Mostly in 2009Mostly in 2009–– Likely been in CA for more than 5 yearsLikely been in CA for more than 5 years

Walnut twig beetle Walnut twig beetle –– First collected in 1959 in L.A. Co.First collected in 1959 in L.A. Co.–– Occurs in many counties from San Diego to Occurs in many counties from San Diego to

Shasta Co.Shasta Co.

WALNUT SPECIES USED IN AGWALNUT SPECIES USED IN AG

Commercial Nut ProductionCommercial Nut Production–– English walnut (English walnut (JuglansJuglans regiaregia))–– 243,000 acres in CA in 2007243,000 acres in CA in 2007–– ~ 100% of U.S. production in CA~ 100% of U.S. production in CA

Nursery Seed TreesNursery Seed Trees –– Black walnutBlack walnut–– J. J. hindsiihindsii, J. , J. hindsiihindsii x x J.nigraJ.nigra hybrid hybrid

Rootstocks Rootstocks –– both from Black walnut both from Black walnut sourcessources–– Northern CA blackNorthern CA black–– Seedling Paradox hybrid (more vigor)Seedling Paradox hybrid (more vigor)

Near Rio Oso, Sutter Co., 88 yr Old Juglans nigra in a Backyard,April 14, 2009

Larval and adultP. juglandis were present beneath the bark of the main stem in mid-April;therefore larvae can overwinter in California.

The remainder of the crowncollapsed in early July 2009.

P. juglandis was trapped landing on the main stem of this tree into Oct. 2009.

PresenterPresentation NotesMid-April 1st caught. Highest catches July & Aug. See transverse galleries on a limb. Most susceptible

Yuba City, Sutter Co., Commercial Orchard of ~20 yr Old J. hindsii x J. nigra interplanted by row with J. regia, July 27, 2009

Mainly infection and infestation in black walnut hybrids, not in English walnut.

Photos: J.K. Hasey,UC Cooperative Extension,Sutter/Yuba Counties;S.J. Seybold, and L. Strand,UC Statewide IPM

INFECTED PARADOX INFECTED PARADOX ROOTSTOCKROOTSTOCK

Geosmithia sp. was isolated from seedling Paradox rootstock in same orchard in Sutter Co.

SURVEY CROWN RATINGSURVEY CROWN RATING

2- Twig Dieback orLimited Crown Thinning

1- Healthy Tree5 – Dead Tree

2 3

4

3- Moderate Crown Thinning

4 – Excessive Crown Thinning to Major

Branches

““SpeciesSpecies”” NN Percentage Infected Percentage Infected (mean (mean ±± S.E.)S.E.)

English walnut (English walnut (J. J. regiaregia) ) on on Paradox hybrid rootstockParadox hybrid rootstock

329329

00

Black walnut hybrid (Black walnut hybrid (J. J. hindsiihindsii xx nigranigra) on) onParadox hybrid rootstockParadox hybrid rootstock

217217

24.424.4±± 2.9%2.9%

0

5

10

15

20

25

30

Low Medium High

# of

infe

cted

tree

s

Survey of Commercial Orchard for TCD,Sutter Co., California, Sept.-Oct., 2009

Infection severity level based oncomposite survey data of crown rating,branch stain rating, stem stain rating,and presence/absence of WTB exit holes

Level of Infection

Geosmithia sp. wasisolated from one specimenof English walnut, which was removed prior to the disease survey.

PresenterPresentation NotesSlide includes blocks 2 & 3 surveys.

Infected English Walnut TreesInfected English Walnut Trees

Top-Howard cv. in Sutter CoBottom-Howard cv. in Solano Co. (2 trees)

Tulare cultivar in Tulare Co.

All English trees stressed with trunk cankers or rootproblems. Appears not to bea significant host to beetle

SUMMARY: WALNUT SPECIES SUMMARY: WALNUT SPECIES CONFIRMED in CACONFIRMED in CA

SpeciesSpecies UrbanUrban Riparian/Riparian/ NativeNative

AgAg

J. J. nigranigra XXJ. J. hindsiihindsii XX XX XX

J. J. hindsiihindsii x J. x J. nigranigra

XX

J. J. regiaregia XX

J. californica XX XX

Paradox Paradox rootstockrootstock

XX XX

OTHER CONSIDERATIONSOTHER CONSIDERATIONS

Cultured black walnut seed from Cultured black walnut seed from infected branches of infected branches of J. J. hindsiihindsii x x J. J. nigranigra–– NoNo GeosmitihiaGeosmitihia found on hull or in nutfound on hull or in nut

Fusarium not found yet in CAFusarium not found yet in CA Beetle may successfully colonize Beetle may successfully colonize

stressed treesstressed trees There is the susceptibility issue of There is the susceptibility issue of

tree species to both the beetle and tree species to both the beetle and to the fungus.to the fungus.

PresenterPresentation NotesMay land randomly, taste and stay based on suscep. Of sp.

Research/slide: Ned Tisserat

PresenterPresentation NotesThe experiment hasn’t been repeated and that this only shows possible susceptibility to the fungus and not the beetle or complex.  For example, I really don’t think butternut is a good host for the beetle (similar to J. regia) whereas I think J. hindsii is probably more susceptible than the graph illustrates because it is damaged more by the beetle. 

PRESENT & FUTURE PLANSPRESENT & FUTURE PLANS

KochKoch’’s postulates in CAs postulates in CA

Testing insecticides and fungicides Testing insecticides and fungicides next spring on infected and nonnext spring on infected and non-- infected walnut treesinfected walnut trees

More extensive surveys of More extensive surveys of J.J. regiaregia and rootstocks for the diseaseand rootstocks for the disease

Thank YouThank You

Questions?Questions?

Photo by Elizabeth Fichtner

THOUSAND CANKERS DISEASE of WALNUT: STATUS in CALIFORNIATHOUSAND CANKERSACKNOWLEDGEMENTS Slide Number 4Slide Number 5SYMPTOMSCALIFORNIA STATUSWALNUT SPECIES USED IN AG Slide Number 9Slide Number 10INFECTED PARADOX ROOTSTOCKSURVEY CROWN RATINGSlide Number 13Infected English Walnut TreesSUMMARY: WALNUT SPECIES CONFIRMED in CAOTHER CONSIDERATIONSSlide Number 17PRESENT & FUTURE PLANSThank You