Walnut in the West Death by a Thousand Cankers • Colorado State University – Ned Tisserat, Whitney Cranshaw, Curtis Utley, Emily Freeland, Bill Jacobi • Boulder County CO ‐ Kathleen Alexander • CO State Forest Service‐ David Leatherman • USFS California ‐Steven Seybold • UC Davis ‐ Andy Graves; Chuck Leslie • Institute Perennial Plants for Food and Bioenergy (IPPFB), UT – T. Ford, R. Funk • USFS Purdue‐Keith Woeste • U Missouri‐ Mark Coggeshall • U Tennessee‐ Scott Schlarbaum • Oregon State –Jay Pscheidt • Czech Republic – Miroslav Kolarik • Funding USFS, USDA‐CSREES Black Walnut (Juglans nigra)

• Not native to western USA • Not a major component of urban landscape but it is a tough tree – Street trees – Backyards – Farmsteads • Trees can grow to very large sizes in Oregon – Also have hybrids

Black Walnut Decline and Mortality in Utah in 90’s • Walnut twig beetle collected near Salt Lake City UT in 1988; but walnut mortality not reported until 1990’s • "If I get a little personal and even a little sentimental, I hope you will forgive me," President Hinckley said as he began to describe the origin of the pulpit. • "Every year at this season we planted trees," he said. "Well, some 36 years ago I planted a black walnut. It was in a crowded area where it grew straight and tall to get the sunlight. A year ago (1999?), for some reason, it died." Walnut pulpit in Mormon • "The first time I saw the wood was when Conference Center Brad had the log in the back of his pickup truck,“ (Intermountain Wood Products of Salt Lake UT) Black Walnut Decline and Mortality in Oregon (1990’s?) • Always associated with presence of twig beetle • Progression slower than in Colorado? • Reasons? • Walnut hybrids common? • Larger trees? • Thicker bark? • Different weather (less stress)? Note symptomless walnut at end of row Extensive Mortality In New Mexico 2001

• Elimination of black walnut near Santa Fe – Walnut twig beetle found • Reports of dieback in Albuquerque 2009 – Thousand cankers disease (TCD) confirmed in 2010 Black Walnut Mortality in CO

• Walnut decline first observed in Colorado Springs and Boulder around 2001‐2002 – May have been years earlier in western Colorado (90’s) • Substantial mortality in Colorado Springs and Boulder by 2004 – Walnut twig beetle and drought suspected • Black walnut eliminated in Colorado Springs by 2008 • Well over 2,000 trees dead in Denver‐Boulder and surrounding area; few surviving trees in Boulder Red Areas indicate where Geosmithia and Pityophthorus juglandis have been found since 2008 Initial Symptoms Subtle and Easily Confused With Other Problems May See Resprouting But Sprouts Also Succumb September 2008

June 2008 June 2009 Walnut Twig Beetle Pityophthorus juglandis • Walnut twig beetle found in Colorado 2003 on black walnut • First record of insect on Juglans major in New Mexico (1927) – native to the Southwest?, California? – Twig beetles normally attack small, weakened twigs

Range of Juglans major Identification of Walnut Twig Beetle, Pityophthorus juglandis Blackman Slide courtesy (Coleoptera: Scolytidae) OCD: Almost compulsive boring and tasting S. Seybold An “Über” Vector of TCD behavior on host branches

Concentric arcs of Two rows of tubercles asperities The walnut twig beetle is a minute bark beetle.

It is one of few Pityophthorus species that develop in hardwoods. Great picture by Jim LaBonte, OR Dept. Agriculture!

Pityophthorus bark beetles are collectively known as “twig beetles” because they normally restrict damage to small diameter twigs. Walnut Twig Beetle • Very aggressive on black walnut – Most galleries on branches >1 inch diameter – Attacks will occur on main trunk • Entrance holes very difficult to see J. regia • Trapping is very inefficient using yellow traps or Lindgren funnels • Most beetles caught in late summer Beetle Captures 45

40

35

30

25

20

15

10

5

0 How Does Such a Small Beetle Kill Such A Big Tree? Summer 2007- Coalescing cankers consistently noted around beetle galleries

• Beetle galleries and East side of trunk cankers not evenly distributed on branches or trunk – More damage on lower side of branches – More damage on one West side of trunk side of trunk? • Often west side of tree more damaged? • # galleries and cankers on tree is enormous!! Cankers Initially Restricted to Phloem and Don’t Extend into Cambium

Outer bark Phloem Eventually Cankers Will Kill Cambium Cankers on Walnut (Left) Differ From Open‐ Faced Cankers (Ash Tree on Right) Summer and Fall 2007 – fungus consistently isolated from cankers Geosmithia ‘morbida’ • Anamorphic genus – (Ascomycota:Hypocreales) – No sexual state known • Off‐white to buff in culture, often lobed • Dry conidia – Unlike Ophiostomatoid and ambrosia fungi (e.g. in Raffaelea in Laurel wilt) • Thermotolerant – Optimal 25‐32 ⁰C – Will grow at 37 ⁰C (99 ⁰F) – Will survive 42 ⁰C (107 ⁰F) Geosmithia ‘morbida’ has a yeast phase Geosmithia species associated with numerous beetles in Europe but has not been reported as plant pathogen Geosmithia species Insect Host G. fassatiae Scolytus intricatus Quercus spp. Scolytus rugulosus Malus G. langdonii Scolytus intricatus Quercus spp. Scolytus rugulosus Malus Ernoporicus fagi Fagus Scolytus multistriatus Ulmus G. obscura Scolytus intricatus Quercus Scolytus carpini Carpinus Geosmithia OTU’s Ernoporus tiliae Tilia Hylesinus orni Fraxinus Ips typographus Picea Scolytus schevyrewi Ulmus Trypophloeus Populus Xyloborinus saxeseni Ulmus Xylosandrus mutilatus ? Geosmithia also has been isolated from frass, beetleA galleries,B and beetles

Photo courtesy Dr. A. Graves U.C. Davis Acremonium alternatum AY566992 G. puterillii AF033384 0.92 G. sp. 27 RJ0911 0.92 AJ578485 OTU2 AJ578487 OTU5 1.00 RJ137m 0.70 G. pallida 0.98 CCF3638 OTU23 0.49 AJ578488 OTU3 species complex 0.71 AJ578486 G.pallida type 0.94 MK1758 0.78 „G. rubra“ AM181464 OTU1 0.86 1.00 G. sp. 20 CCF3641 0.94 „G. adriatica“ CCF3655 OTU10 „G. rufescens“ MK1803 0.92 G. lavendula AF033385 G.sp. 26 MK1797 G. obscura AJ784999 0.97 G. obscura AM181460 G. sp. 8 AM181420 0.90 „G. microcorthyli“ CCF3861 0.75 G. sp. 16 AM181422 G. sp. 35 RJ167m G. sp. 32 MK1801 G. sp. 30 MK1824 0.82 0.82 0.95 G. sp. 30 RJ156m G. sp. 33 MK1809b Analysis courtesy 0.55 G. sp. 34 MK1832 0.70 G. sp. 31 MK1793 G.langdoni AJ578481 M. Kolarik G. flava AJ578483 G. fassatiae AJ578482 0.50 1247 CO 0.88 1217 CO 1234 AZ 1227 CA 0.65 1270 CA 1222 UT G. “morbida” 1259 OR 0.94 1239 CO 1223 UT 1273 CO 0.89 1269 CA 1218 CO Pinaceae G. sp 11 AM181419 G. sp. 29 CCF3753 G. sp. 21 MK592 0.53 G. sp. 12 AM181431 0.42 0.74 G. sp. 13 AM181439 1.0 1226 FortCollins CO G. sp. 40 CCF3563 Isolate from S. schevyrewi Angiosperms „G. eupagioceri“ CCF3754 G. sp. 9 CCF3703 from Ulmus + Cupresaceae G. sp. 25 MK1805 G. sp. 28 RJ278m 0.79 G. sp. 44 MK1804 0.84 G. sp. 22 CCF3652 0.69 G. sp. 24 MK1822 0.1 It’sA a Food Fight! • Bark maceration • Pityophthorus, ambrosia beetles, other insects • Geosmithia, Fusaria &

manyB other fungi Fusarium Canker of Walnut • Reported in 80’s in Minnesota, Wisconsin, Kansas following harsh winter conditions • Associated with ambrosia beetles Death by a Thousand Cankers • Initial beetle attack – Cankers form around beetle galleries, but initially localized in phloem – Cankers coalesce, eventually penetrate bark to cambium; resulting in branch dieback – It may be years between initial beetle attack and visible symptoms • The death spiral – Tree vigor declines – Mass attack by beetles on trunk; many cankers – Secondary fungi invade (Fusarium solani and others) – Trees are killed Distribution of 1000 Cankers in Colorado rDNA ITS haplotypes of G. morbida are not geographically or host specific Where Did 1000 Cankers Originate? • Pityophthorus juglandis and Geosmithia ‘morbida’ widespread on J. major in New Mexico and Arizona – But our survey is not complete • J. major not in a state of decline in its native range • Do isolates vary in aggressiveness to black walnut? – not so far What about the California Walnuts?

J. californica

J. hindsii Thousand Cankers Disease: Areas of Interest in CA

J. regia J. regia J. regia J. hindsii J. californica

Slide Courtesy of A.D. Graves, UC-Davis Dept. Plant Pathology Thousand Cankers Disease: Areas of Interest in CA

J. regia J. regia J. regia J. hindsii J. californica

Slide Courtesy of A.D. Graves, UC-Davis Dept. Plant Pathology Thousand Cankers Disease: Areas of Interest in CA

Davis, Yolo Co.: Branch dieback and mortality on Juglans hindsii on city streets and along rural highways, June-Aug., 2008

J. regia J. regia J. regia J. hindsii J. californica

Slide Courtesy of A.D. Graves, UC-Davis Dept. Plant Pathology Thousand Cankers Disease: Areas of Interest in CA

Winters, Solano Co.: Northern California black walnut is dying in its native habitat in the lower Sacramento River Valley

J. regia J. regia J. regia J. hindsii J. californica

Slide Courtesy of A.D. Graves, UC-Davis Dept. Plant Pathology Thousand Cankers Disease: Areas of Interest in CA

Davis, Yolo Co.: Black walnuts are dying in research germplasm collections, e.g., UCD Walnut Collection and NCGR. Mortality of a 12-13 yr old Juglans californica J. regia on Paradox Rootstock, Aug. 11, 2009 J. regia J. regia J. hindsii J. californica

Slide Courtesy of A.D. Graves, UC-Davis Dept. Plant Pathology Thousand Cankers Disease: Areas of Interest in CA

Piru Lake, Ventura Co.: Native endemic stands of Juglans californica in the Los Padres National Forest showing crown dieback and tree mortality, Aug. 27, 2008

J. regia J. regia J. regia J. hindsii J. californica

Slide Courtesy of A.D. Graves, UC-Davis Dept. Plant Pathology Thousand Cankers Disease: Areas of Interest in CA

Near Glendale, Los Angeles Co: Highly symptomatic native Juglans californica in a residential backyard, Montecito Heights, June, 2009

J. regia J. regia J. regia J. hindsii J. californica

Slide Courtesy of A.D. Graves, UC-Davis Dept. Plant Pathology Black Walnut vs. Pecan Is Juglans regia at Risk? Two dead Juglans nigra on left, healthy Juglans regia on right

Photo courtesy Marion Murray, Utah State University Juglans regia (Denver) in fall 2008 and June 2010. Juglans microcarpa in Denver 2010 Butternut (J. cinerea) in Denver area 2010 Susceptibility of other Juglans, Carya species? Juglans microcarpa Inoculations

Juglans major

Juglans nigra Canker Development Following Inoculation With Geosmithia

160 140 PDA 2 120 Aspergillus (mm

100 Geosmithia Isolate 1217 Area 80 Geosmithia Isolate 1218 60 40 Discolored 20 0

Tree Species in Order of Susceptibility to Geosmithia Discolored area 6 wk after inoculation; mean of 6 trees 2,000 **

**

1,500

1,000 ** **

** **

** ** ** ** 500 NS NS ** ** NS NS NS NS NS NS NS NS 0 1,500

** ** ** ** 1,000 Inoculated vs. control ** ** **

% increase in discolored area % increase in discolored * NS

500 **

* NS NS * NS NS NS NS NS NS 0 C.ovata C.illinoensis J.major J.californicaB J.hindsii J.microcarpa J.californica J.regia J.cinerea J.ailantifolia J.nigra

Isolate 1217 Isolate 1218 1000 Cankers Poses Grave Risk to Walnuts • Dieback and decline of Juglans spp. in California • Rapid mortality of black walnut in numerous regions of the West – Disease widespread – Very efficient, aggressive vector – Aggressive fungus • What happens if disease establishes in native range of black walnut? – What if it doesn’t/ can’t cause damage in native range? • Can we take that chance by ignoring this? It Will Be Too Late To Do Anything if TCD Establishes in Native Range • Other exotics introduced into native range of susceptible trees – Butternut canker – Chestnut blight – Emerald ash borer – Laurel wilt • TCD is not yet in native range: we can do something Can We Contain 1000 Cankers? Do We Have the Will to Contain It? Beetle infested black walnut with bark attached as advertised on the internet What Should We Do Nationally?

• Walnut wood harbors the insect and fungus • We don’t know for how long, but moving wood is a very bad idea! Over 23,000 beetles emerged from these logs How wood might move Black Walnut Makes For Great Firewood in Colorado (and elsewhere) No One in the West Wants to Destroy Infested Logs! Denver Craigslist Postings (10/29/2009)

. ‘I have a full truckload of black walnut wood’ ‘We have a straight, tall walnut tree, lost to disease, that needs to come down. We thought we'd offer it up to woodworkers before having it hauled off for firewood.’ For sale ‐ 3 stunning walnut crotch slabs. 1 bookmatched set and one other sequential slab all from the same log. These were recently cut so they are still green, you buy green, you save a pile of green. Transcontinental Movement of Large Logs • Myth that logs are not shipped from West to East What About Bark Removal? • Beetles apparently emerged from wood and then tried to reenter logs • Debarking may not be a safe measure • Some woodworkers don’t like bark removed What about chipping? Walnut twig beetles were able to complete development in larger pieces following chipping Right Now We Need To Prevent Movement of ANY Form of Wood! What About Chemical Treatments?

• Not a solution to the long term survival of black walnut in native range • May have some use in the West What About Drenching Sprays?

• Drenching branch sprays (pyrethroids and others) for walnut twig beetle has not been effective ‐ possibly because of poor timing Soil treatments and Walnut Twig Beetle • Imidacloprid (Merit) use in Boulder may have slowed progression, but did not always save diseased trees – However, most applications made curatively rather than preventively – Need higher rates? • Trials planned for Denver in 2010 – Imidaclorprid, abamectin, possibly others – Dinotefuran may work better for this application, but doesn’t have food crop tolerance – What about fungicides? What Needs to Be Done

• Strong public education on the threat of Thousand Cankers Disease to black walnut in its native range – Arborists, Woodworkers, Homeowners – http://www.colostate.edu/Depts/bspm/extension %20and%20outreach/thousand%20cankers – htmlhttp://mda.mo.gov/plants/pests/thousandca nkers.php – • Information What Needs to Be Done

• Immediate restrictions on the movement of walnut wood – State quarantines – National quarantines • We must stop this! Containment of 1000 Cankers • Don’t move infested logs or lumber with bark attached • Sanitation in infested areas probably won’t help • Movement of fresh debarked lumber? • Movement of wood chips? Average Geosmithia Canker Size Utah Study

2 100

mm 90 in

80 70 Geo. Iso. 1222 Area

60 50 Geo.Iso. 1223 40 Canker

30 20 10

Average 0

Juglandaceae Species inoculated ‘Those who do not remember the past are condemned to repeat it’ Black Walnut (Juglans nigra) in the • Not native to West western US • Not a major component of urban landscape – Street trees – Backyards – Farmsteads Oregon • It’s a tough tree! March 2008‐ Canker formation in black walnut 8 weeks after inoculation with isolates of Fusarium solani and Geosmithia ‘morbida’ Isolate Number of inoculation Average and range ( ) sites developing of canker lengths (mm) cankers Fusarium solani 917 2/8 19.0 (16-22) Fusarium solani 1179 6/8 21.0 (10-40) Geosmithia 1217 8/8 57.0 (29-130) Geosmithia 1218 8/8 46.5 (31-60)

AB

F. solani G. morbida Geosmithia is a bark, and not a vascular pathogen

Canker formation 4 weeks after inoculation in field (Utah), original inoculation point 3 mm diam. Adult twig beetle tunneling on excised stem of Juglans nigra after 24 hours Canker development 4 weeks after placement of adult twig beetles on excised stem of Juglans nigra Other Canker Fungi • Very long, vertical cankers on trunk during final stages of decline • Fusarium solani isolated from cambium in 2006 (but not from around beetle galleries) – Other Fusarium species have also been recovered

WalnutDead Walnuttwig beetles Wood readily Can breed Host in Bark logs Beetles and Fungus Two logs, ca 5 1/2-in diameter, 18-in length 23,040 Beetles/2 logs

= 35+ Beetles/inch2 2006 in Boulder Colorado Open‐Faced Cankers Don’t Form

• May see bark cracking around entrance holes, star shaped wounds at leaf scars, and staining on trunk, but these are not diagnostic Could Walnut Twig Beetle Kill the Tree Without Geosmithia? • Geosmithia always associated with insect • Does the fungus enhance the ability to attack Pityophthorus to attack bark? – Reduced vigor? – beneficial to insect? Where Did G. morbida Come From?

1234 AZ

1263Ventura CA 1264Ventura CA • Isolates vary slightly in 1261SanJoaquin CA 1276CSUOval CO 1217Boulder CO DNA (rDNA ITS) sequence 1279Wheatridge CO 1224Boulder CO 1249YoloCounty CA – Suggests at least some 1227Winters CA 1273GoldenCemetery CO 1236Prosser WA genetic diversity 1250Boulder CO

1270SanJoaquin CA 1267SanJoaquin CA 1260 OR ITS rDNA sequencing – Probably not the result 1245Boise ID

1262Ventura CA 3 of a single 1223 UT 1268Ventura CA 1274Wheatridge CO introduction? 1218Boulder CO

1 1269Ventura CA 1258 OR

1 1228Winters CA 1272Ventura CA 1259 OR 1247ColoradoSprings CO

1 1233YoloCounty CA 1256 OR 1266Ventura CA 1246ColoradoSprings CO 1285Delta CO 65 1222 UT 1239Westminster CO 1271GoldenCemetery CO

0.0002 Juglans Germplasm Collection Positive Isolation of Geosmithia from English Walnut, J. regia, Accession No. DJUG0366.1, Block C, Row ?, Tree 1, September 2009

1) Mass attack by walnut twig beetle Red Areas indicate where Geosmithia and Pityophthorus juglandis have been found