Thousand Cankers Disease (TCD) What is it? Where is it? Why is it important? What are we doing about it? Declining black walnut K.Kromroy

What is TCD? Disease of walnuts (some species) Caused by a twig beetle and a fungus together Ned Tisserat, Colorado State Univ.

What is TCD? Two species in Minnesota are affected: Butternut Eastern black walnut www.plantcare.com/.../black-walnut-2127.aspx www.tree-pictures.com/butternut_tree_photos.html Several species of walnut are affected by the disease Arizona walnut (Juglans major), thought to be original host of walnut twig beetle, occurs in southwest United States and Mexico; the twig beetle does not cause major damage, even though it carries the fungus. Mortality of native California black walnut trees (J. hindsii, J. californica) has been recently observed (work by Steve Seybold and Andrew Graves) Two Juglans in Minnesota: Eastern black walnut – very susceptible, butternut – unknown, but TCD was confirmed on a butternut growing in Eugene OR in January 2012 – this is the first report of natural infection of the species The ranges of butternut and black walnut overlap in MN, but butternut occurs farther north

What is TCD? Walnut twig beetle (WTB) Originally associated with Arizona walnut Feeds on inner bark of trunk and branches Walnut twig beetle A minute bark beetle – smaller than a grain of rice Adults and larvae do extensive tunneling in the inner bark One of a group of beetles known as “twig beetles” because they normally restrict damage to small diameter twigs and are not a major problem Which seems true on Arizona walnut, Juglans major, which is likely the original host and occurs in southwest United States BUT, on black walnut species it is very aggressive, and attacks large branches and the main trunk All photos Whitney Cranshaw , Colorado State Univ.

What is TCD? Fungus carried by beetle; introduced into wounds Fungus kills the bark and phloem Causes a canker (dead area below the bark) Jim LaBonte, OR Dept. Ag. Thousand Cankers Disease is similar to Dutch Elm Disease and Oak Wilt in that a fungus is carried by an insect and introduced into the tree. But it is different in that rather than causing a vascular wilt, it causes cankers. Ned Tisserat, Colorado State University

What is TCD? Cankers grow together, girdling and killing the branch or trunk Small cankers enlarge and coalesce Ned Tisserat, Colorado State University

Symptoms of TCD Yellowing, wilting foliage Branch die-back, death Minnesota Dept. of Agriculture Whitney Cranshaw, Colorado State University Initial crown symptoms similar to those caused my many other kinds of stress. Since 2000, many eastern black walnut (Juglans nigra) that were planted as street and landscape trees have died in Colorado, particularly in the cities of Boulder and Colorado Springs. Yellowing, wilting foliage Branch die-back, death

History of WTB and TCD Prior to 2003 1928 Early 1990’s 2001 2003 Original description of WTB, New Mexico Report of black walnut mortality, northern New Mexico; WTB associated. Reports of black walnut decline and mortality in Boulder and Denver, Colorado Reports of black walnut decline and mortality in Oregon & Utah

Original host: Arizona walnut Where is TCD now? 2012 Original host of insect/fungus complex thought to be Juglans major, Arizona walnut, on which the complex results in very little damage. It seems that this insect/fungus complex may be “jumping” to other hosts and thus also expanding its geographic range. REPORTS IN EASTERN US Original host: Arizona walnut

Why is it important? Threatens all eastern black walnut in its native range No known control Native range of butternut overlaps, extends a little further north. Industry very concerned.

Number of Black Walnut Trees over 1″ dbh on Forested Land Data from USFS Forest Inventory & Analysis - on FORESTLAND Missouri ranks first in U.S. Iowa second or third 5.9 million

Black walnut moves through Minnesota – hundreds of logs each year Black walnut logs at rail yard in St. Paul. Origin Iowa, Wisconsin, Illinois, often Minnesota Hundreds of logs/year Unloaded from trucks, wait in yard until loaded into containers for rail shipment to west coast then overseas to Asia – for veneer, then back to US As of 18 January 2013: TCD is prohibited pest under Korea's Plant Protection Act. Impose emergency import restriction of wood products and plants for planting ofvJuglans spp. to prevent possible introduction of TCD and it's vector into Korea Required from states with TCD: Heat treatment before shipping - Phytosanitary certificate (PC) should contain the information on heat (same trt regime as below) Required from states with out TCD: HT treatment: above 56℃ (core temp.) for 30 min. or MB fumigation: in accordance with below fumigation schedule Minnesota Dept. of Ag. Korea’s new regulations

Value of black walnut Social Ecological Culture around walnuts for food Bark used for medicine, dye Ecological Harder to measure Nuts as food for wildlife (squirrels, beaver, red-bellied woodpecker Important species of riparian (riverbank) corridors Slide from Manfred Mielke

What are we doing? PREVENTION Education Regulation EARLY DETECTION

ESTIMATED APPROACH RATE Education: Pathways of Introduction PATHWAY ESTIMATED APPROACH RATE Timber Low; little timber shipped from west to east Firewood Low to moderate; firewood distributors, long-distance campers Wood packing Low to moderate Nursery stock Low; no reports of infested nursery plants Scion wood Low; programs in west revised to prevent spread Natural spread Low; beetle flies 1-2 miles To prevent introduction, must know the pathways. Analysis published on 2009 re movement from west to east. All but one pathway are people What we know now……….. Another not considered – Newton & Fowler, 2009

Pathway: Wood for Hobbyists Internet sales Mail-order companies Hobby shows Homeowner in Bucks County taking down 20-30 trees, most 4-8” dbh, a few much larger. http://www.primocraft.com/Bar-Features/Walnut-Burl-Inlay.html http://www.furnituredesignidea.com/3729/cool-wooden-furniture-heartwood-design-furniture

Pathway: Wood for Hobbyists Black walnut logs, slabs, and burls with bark attached Walnut orchard in CA, with grafted trees – the graft areas make good wood for hobbyists Ohio – WTBs caught in traps at mill site that imports walnut burls from CA – no TCD infested trees yet. http://www.woodweb.com/cgibin/forums/vawp.pl?read=531138 Minnesota Dept. of Agriculture

Education Presentations Newsletters Websites E-mail notices Site visits To Partner organizations Mill owners Loggers Tree care companies Nurseries Industry very interested in protecting the black walnut resource Photos courtesyMike Greenheck

Regulation Who regulates the movement of walnut logs? Infested western states - No APHIS - No Eastern states - Yes Western states – no regulations to prevent movement out of state APHIS – chose not to regulate because the insect/fungus complex thought to be native to the US Eastern States have put interior and exterior quarantines into place

Regulation Explain Interior quarantine – regulates material leaving an infested area Exterior quarantine – regulates material coming into an area to keep out infested material

2011 Visual surveys in 15 states Early Detection USDA APHIS funds Core CAPS 2011 Visual surveys in 15 states Map from J. Juzwik, USFS Federally funded TCD surveys in 15 other states MN 2011 – 2500 walnut trees visually assessed. 5 branch samples collected –no TCD MN 2012 - 885 walnut trees visually assessed around mills or sites previousl id’d and traps at 3 sites A few branch samples. Results pending MN 2013 – trapping at 10 sites – high risk, millIowa and WI Two surveys in Minnesota – worked together: MDA – urban, USFS – other areas Visual surveys – suspicious trees were then sampled and samples processed in state or other selected labs Data in national database Forest Service and MDA conducted visual surveys – no TCD found

Visual Assessment: Early symptoms Thinning crown Yellow or wilting leaves Tree may be infested 7 or more years before showing crown symptoms J.Juzwik, USFS

Symptoms – oozing cankers Minnesota Dept. of Ag.

Actively declining symptoms Whitney Cranshaw, CO State University Limbs die in 1 season W. Cranshaw Colorado and ___ in TN –hard to find early. In TN – low dieback, mildly symptomatic Rapid wilting B.Moltzan, USFS Top-down dieback

Signs Larval galleries Many holes on branches over 1.5″ dbh photos W. Cranshaw , CO State Univ.

Small cankers in inner bark J.Juzwik, USFS

Old cankers under bark on black walnut lose their color Minnesota Dept. of Ag.

Large dead areas on branches and stems J.Juzwik, USFS

What might be mistaken for TCD? Anthracnose Fusarium canker Anthracnose widespread on black walnut in Beaver Creek Valley State Park, 2010 Joseph O’Brien, USFS J.Juzwik, USFS

What else might be mistaken for TCD? Unknown Site stress Tom and Ellie Choinksi near Winona have several black walnuts that are declining, dying. Do not suspect TCD as of August 2011. Some could be site stress – high water. Choinski J.Juzwik, USFS

Insects found on girdled black walnut in Indiana and Missouri: Other insects Insects found on girdled black walnut in Indiana and Missouri: Ambrosia beetles Weevils Bark beetles Similar results in trap catches and branch samples in IA and WI 80% of beetles in MO Asian ambrosia beetle Jjuzwik did study to test attraction of stressed walnut to insects. Girdled base of black walnut trees in 2 states. Felled 3 months later, sampled segment from stem and branch – thousands of beetles found Natasha Wright, Florida Department of Agriculture and Consumer Services, Bugwood.org

Early Detection: a trap with a lure Much better than visual survey and crown sampling Lure available commercially Develop trapping guidelines Survey funding? Lure 2012 Lure avail commercially first time. MN had traps at 3 sites 2013 – traps at 10 sites S.Seybold, USFS

Management Sanitation Tree removal Proper disposal Bury Burn Minnesota Dept. of Ag.

Management Studies in progress because walnut moves! Treatments tested Debarked only Debark + heat Fumigation – methyl bromide Insecticides Protectants Systemics Insect Repellent Results of 2011 studies indicated all heat treatments worked to kill fungus and WTB. Will test more heat trt in 2012 Debarking not practical because too hard to get off all bark – and bad for veneer Insecticides and repellants – don’t hold breath – requires many applications, for systemics, if just a few WTB already present and caused cankers, those cankers will not move chemical as dead phloem. Photo by Kathy Keatley Garvey)

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