Minnesota First Detectors Thousand Cankers Disease (TCD)

Minnesota First Detectors Biology History, distribution, potential impact Prevention and early detection activity What you can do! Updates Thousand Cankers Disease

Minnesota First Detectors Eastern black walnut Butternut Thousand Cankers Disease: a Disease of Walnut (Juglans) Trees Two species in Minnesota are at risk:  Because of butternut canker there are few butternut trees remaining.  Focus here is on black walnut, but signs and symptoms are the same on butternut.

Minnesota First Detectors How to identify a walnut tree  Leaves are compound (more than one blade attached to a single stalk or petiole)  Compound leaves alternate on branch  Leaf margins finely toothed  Fruit is a spherical nut. tbn2.gstatic.com/images?q=tbn:ANd9GcS8UnEOBOSrB mP1pGyfx1jw1lutcdN6ELSYDmLQbCan2mpCt5jt

Minnesota First Detectors ees/blackwalnut.html How to identify a walnut tree ry/html/P html  Bark is dark brown to black and chocolate-brown when broken  The pith or center of the twigs is divided into empty chambers by plates, for the whole length of the twig

Minnesota First Detectors Whitney Cranshaw, Colorado State Univ. Thousand Cankers Disease is caused by an insect and a fungus together Walnut twig beetle (WTB) Smaller than a rice grain Usually damages only small twigs But aggressive on black walnut Tunnels extensively under bark of large branches and trunk The Insect

Minnesota First Detectors Is carried by beetle Into wounds created by tunneling Fungus kills the bark and phloem = a canker Ned Tisserat, Colorado State University The Fungus Jennifer Juzwik USFS Jim LaBonte, OR Dept. Ag. Fungal spores Disease is caused by an insect and a fungus together

Minnesota First Detectors Ned Tisserat, Colorado State University Cankers grow together This girdles and kills the branch or trunk

Minnesota First Detectors Confirmed in Colorado: black walnut mortality is due to insect x fungus combo History and Distribution Original description of walnut twig beetle in New Mexico Report of black walnut mortality in New Mexico associated with walnut twig beetle Reports of black walnut decline and mortality in several western states Why do we care?

Minnesota First Detectors We care because it threatens eastern black walnut in its native range  Native to 32 states  Estimated 306 million live black walnut trees  Concentrations in Missouri, Ohio and Tennessee River basins  At northernmost edge of range, even Minnesota has almost 6 million TCD! Miles, P.D Forest Inventory EVALIDator web-application

Minnesota First Detectors Insect confirmed in Maryland History and Distribution continued Disease confirmed in Tennessee: FIRST report in native range Disease confirmed in Virginia and Pennsylvania Disease confirmed in North Carolina Disease confirmed in Ohio and Italy Fungus named Lure for insect trapping ready

Minnesota First Detectors Potential impact of thousand cankers disease Minnesota Dept. of Ag. wooden-furniture-heartwood-design-furniture Wood for Hobbyists Logs for Veneer Black walnut is a highly valued wood

Minnesota First Detectors 10,000 metric tons of black walnuts are harvested annually in the United States After hulled and shelled, most nuts are packaged for retail; some used in ice cream, commercial baking, candy making Shells are ground and used for metal cleaning, oil well drilling, as ingredient in some industrial products ( Potential impact of thousand cankers disease Nuts support an industry

Minnesota First Detectors Nuts as food for wildlife (squirrels, beaver, red-bellied woodpecker Important species of riparian (riverbank) corridors Potential impact of thousand cankers disease Black walnut also has ecologic value

Minnesota First Detectors Using what we know about the pathways to target efforts for Prevention and Early detection The threat is real: What are we doing? Pathways for thousand cankers disease Logs for veneer Wood for hobbyists Firewood Nursery stock Scion wood Natural spread

Minnesota First Detectors Photos courtesy Mike Greenheck Prevention: Education Presentations Newsletters Websites notices Site visits To Partner organizations Mill owners Loggers Tree care companies Nurseries

Minnesota First Detectors Prevention: Regulation  Infested western states? No  USDA? No  Eastern states? Yes Who regulates the movement of walnut ?

Minnesota First Detectors Prevention: Regulation

Minnesota First Detectors Early Detection Survey: Trapping  11 sites, 3 traps/site  Railyard  Mills that use or store walnut  High-value plantations  Stands in high traffic locations  Late June – late Sept.  1 lure change 2013

Minnesota First Detectors Early Detection Survey: Trapping  4-cup Lindgren funnel trap, hung from black walnut branch  Hung on poles if no trees nearby  Attached lure for walnut twig beetle  Insects accumulate in cup, collected every 2 weeks

Minnesota First Detectors Early Detection Survey: Trapping Walnut twig beetles are very small 166! 2013 results: NO walnut twig beetles Andrea Hefty, Univ. of Minnesota

Minnesota First Detectors Early Detection Survey: Visual Assessment of Tree Condition  Surveys since 2011, mid to late summer  Collaborate with U.S. Forest Service  Select urban and rural sites in central and southern Minnesota  Use standardized data collection sheet  Collect branches from suspect trees for examination in the lab  NO thousand cankers disease

Minnesota First Detectors Early Detection Survey: Visual Assessment  In 2013, assessed 745 black walnut at 17 sites  2 suspect trees  Collected branch samples  NO thousand cankers disease Many suspect beetle holes Suspect tunneling under bark Suspect canker-like areas around the tunneling

Minnesota First Detectors In the absence of nuts, which one of the following might be the most helpful for walnut tree identification? A. Look for compound leaves that are opposite on the branch B. Pick some fresh leaves from the tree or old leaves on the ground and chew them to see if they taste like walnuts C. Find a twig on the tree or on the ground and break it open to look inside

Minnesota First Detectors Your tree is probably black walnut if the inside of your broken branch looks like? A. B. C. A B C

Minnesota First Detectors If the tree is a walnut look for these signs & symptoms  Thinning crown  Yellow or wilting leaves  Branch dieback J.Juzwik, USFS

Minnesota First Detectors Signs & symptoms Whitney Cranshaw, CO State University B.Moltzan, USFS Rapid wilting Top-down dieback

Minnesota First Detectors Signs & Symptoms photos W. Cranshaw, CO State Univ. Many pinhead size holes on branches over 1.5″ dbh Tunneling and larval galleries

Minnesota First Detectors Signs & Symptoms Minnesota Dept. of Ag. Oozing canker visible on branches with bark

Minnesota First Detectors New, small cankers under bark Note color contrast on live branches J.Juzwik, USFS Signs & Symptoms

Minnesota First Detectors Old cankers under bark Note lack of color contrast on dying branch Minnesota Dept. of Ag. Signs & Symptoms

Minnesota First Detectors Cankers have enlarged and grown together to create large dead areas on branches and stems. Must remove bark to see clearly. J.Juzwik, USFS Signs & Symptoms

Minnesota First Detectors Thousand cankers disease look-alikes  A few other diseases as well as site stress could be mistaken for thousand cankers disease  But it can be difficult for even experts to determine  Please report any suspects to J.Juzwik, USFS Choinski

Minnesota First Detectors Rapid detection & tree removal, followed by burying or burning is best Beetles can emerge by the thousands from any wood pieces Work in progress on a bio control substance Still no effective tree treatments Updates: Management Minnesota Dept. of Ag.

Minnesota First Detectors Wood treatment for thousand cankers disease Processed lumber (kiln dried, squared-edges, bark free) is “safe” because insect activity is only in the phloem. Debarking alone does not ensure elimination of the pathogen from the sapwood surface. Heat treatment alone: “the current heat treatment schedule for the emerald ash borer (60C core temperature for 60 min) is more than adequate for treating walnut firewood.” Mayfield et al., 2014 BUT: Preliminary results of another study show walnut twig beetles re-infest some treated wood. Updates: Management

Minnesota First Detectors Other research updates Insects Several different insects are found on TCD-infected trees in other states in addition to the walnut twig beetle - ambrosia beetles, weevils, other bark beetles Similar insects found in traps in states without TCD Roles unclear at this time Fungi Several different fungi are found on TCD-infected trees in other states in addition to the disease fungus, Geosmithia morbida Roles unclear at this time

Minnesota First Detectors Questions?