Butternut and Butternut Canker

Butternut and Butternut Canker Casey Jennings 10 December 2013 Photo: Casey Jennings

Introduction Uncommon but valuable species (Rink 1990) Lumber valued for furniture and cabinetry Can be tapped for syrup Most valued for its nuts Nut husks used for die Not grown commercially

Introduction Threatened by butternut canker (Rink 1990) Butternut canker incited by Ophiognomonia clavigignentijuglandacearum (Broders and Boland 2011) Manfred Mielke, USDA Forest Service, Bugwood.org

Management Objective To maintain butternut as a naturally regenerating component of the forest throughout its native range for timber and nut production, and to restore it to those portions of its range from which it may have been extirpated with plantings of cankerresistant trees.

Tree Adaptations Tolerates temperatures from 30 to 105 degrees Fahrenheit (Rink 1990) Large natural range in eastern North America Occurs as scattered individuals (Rink 1990) Rink 1990

Tree Adaptations Grows best on rich, welldrained loamy soils near streams (Rink 1990) Tolerates rocky, dry sites (Farlee and others 2009) Shade intolerant (Rink 1990) Often found on steep slopes which receive sunlight, riparian areas, abandoned fields, edges of woodlands and other disturbed sites (Farlee and others 2009) Photo: Casey Jennings

Tree Adaptations Butternut rarely lives beyond 75 years (Rink 1990) Generally grows 40 60 feet tall and 12 to 24 inches DBH Rarely grows to 100 feet tall and 36 inches DBH (Rink 1990) Produces seed (nuts) irregularly starting at about 20 years (Farlee and others 2009) Seeds survive 2 years in soil and require 120 days of stratification between 32 and 40 degrees Fahrenheit to germinate (Farlee and others 2009)

Butternut Canker Symptoms Sunken, elliptical cankers on any portion of the tree, including stems, branches, twigs, and the buttress roots (Halik and Bergdahl 2002) Cankers have inky black centers and white margins, and larger cankers are often perennial (Michler and others 2006) These perennial cankers eventually girdle branches and eventually the stem (Halik and Bergdahl 2002) Photo: D. Bergdahl. http://www.uvm.ed u/~dbergdah/butnut /butnut.html

Butternut Canker Symptoms Trees typically take several years to die and do not resprout (Rink 1990) Typically stem cankers form 1 to 3 years after cankers form on branches in the crown, and the first branch cankers form in the lower crown (Tisserat and Kuntz 1984) Photo: Casey Jennings

Tree Functions Impacted Cambium killed where cankers are (Ostry and others 1996) Cankers girdle branches, resulting in crown loss (Halik and Bergdahl 2002) Cankers girdle stem and roots, causing mortality (Halik and Bergdahl 2002) Photo: Tim Parsons http://sites.middlebury.edu/middland/files/2013/09 /butternut canker dead cambium.jpg

Impact on Stand and Forest Widespread infection and mortality (Rink 1990) A survey in Wisconsin showed 92 percent of butternut trees infected and 27 percent dead (Farlee and others 2009) Vermont in 1978 had no reports of butternut canker, but by 1996 was found throughout that state with 94 percent of trees infected (Katovich and Ostry 1998) Reported to be eliminated from the wild in SC and NC (Rink 1990) Butternut was always a minor component of eastern forests (Rink 1990)

Pathogen Signs Thin black stromatic layer formed underneath bark (Broders and Boland 2011) Stromatic columns (hyphal pegs) of interwoven mycelia form (Broders and Boland 2011) Hyphal pegs and conidiospores. Photograph: D. Bergdahl. http://www.uvm.edu/~dbergdah/butnut/butnut.html

Pathogen Signs Pycnidia at the bases of the hyphal pegs (Kuntz and Nair 1982) Conidia come from the pycnidia, extruded in the form of a sticky mass of cirri (Kuntz and Nair 1982)

Pathogen Life Cycle No sexual state known (Broders and Boland 2011) Conidia enter bark via wounds or other openings(halik and Bergdahl 2002) The conidia require at least 16 hours of dew at a temperature of 20 degrees Celsius in order to germinate (Tisserat and Kuntz 1984) Infection can be rapid, sometimes killing branches of the host tree within 1 month of inoculation (Tisserat and Kuntz 1984) Pycnidia form along stroma at the bases of the columns (Kuntz and Nair 1982) Conidia come from the pycnidia, extruded in the form of a sticky mass of cirri (Kuntz and Nair 1982)

Pathogen Life Cycle Sporulating pycnidia are born by the tips of the stromatic columns to increase dispersal of spores (Kuntz and Nair 1982). Dissemination via rain drops and insects (Broders and Boland 2011) Spores remain viable for up to 8 hours in cool weather (Tisserat and Kuntz 1983) Rain splash and stem flow transports spores down the tree (Halik and Bergdahl 2002) At least 17 species of beetles have been found with spores (Halik and Bergdahl 2002) Photo: D. Bergdahl http://www.uvm.edu/~dbergdah/ butnut/butnut.html

Pathogen Life Cycle In the absence of butternut trees, it can survive on trees in the genera of Juglans, Quercus, Carya, Corylus, Prunus and Castanea, generally without being fatal to the host, except to certain Juglans species such as Juglans regia (Ostry and Moore 2007) The fungus can persist and continue producing conidia on dead trees for up to 20 months (Tisserat and Kuntz 1984)

Predisposing Factors Pathogen likely originated outside North America First identified in Wisconsin in 1967 (Broder and others 2012) Reports of butternut decline and dieback which were likely caused by butternut canker were made in the 1920 s (Broder and others 2012) Blamed on Melanconis juglandis in 1920 s, but this is unlikely to have been the cause (Broder and others 2012) Cause identified as Siroccocus clavigignenti juglandacearum in 1979, recently renamed Ophiognomonia clavigignentijuglandacearum (Broders and Boland 2011) Recently found in China as an endophyte of Shantung maple (Acer truncatum) (Broders and others 2012) Japanese walnut (Juglans ailantifolia) was widely planted in the early 1900 s and is resistant (Broders and others 2012)

Predisposing Factors Most butternut trees lack resistance (Ostry and Moore 2007) Cool, moist conditions favor the pathogen (Tisserat and Kuntz 1984)

Inciting Event Butternut canker is incited when the exotic fungal pathogen, Ophiognomonia clavigignenti juglandacearum, infects a host tree, leading to canker formation (Rink 1990).

Contributing (Secondary) Factors Secondary infections of highly diseased trees with the fungus Melanconis juglandis often occur (Broders and others 2012) Not significant Photo: D. Bergdahl http://www.uvm.edu/~dbergdah/butnut/bu tnut.html

Preemptive Control Options Prune lower branches Moist, humid conditions due to shade Where infections first occurr (Tisserat and Kuntz 1984) Maintain vigor of tree by thinning competitors to provide sunlight None of these options will truly prevent infection of susceptible trees

Monitor and Survey Cankers with an inky black center, Generally first found in the lower crown on leaf scars and buds (Ostry and others 1994) The cool, wet conditions of spring are favorable to the pathogen Look for the presence of butternut canker after Spring

Reactive Measures Do not immediately remove infected trees Trees have been known to survive for 30 years if vigorous (Farlee and others 2009) Pruning infected branches when the tree is initially infected Infections in the crown often spread to lower portions of the tree via rain (Halik and Bergdahl 2002) Could slow down the formation of cankers on the stem

Reactive Measures Retain trees that meet the following: At least 50 percent of live crown and no stem or root cankers With 70 percent of their crowns remaining and 20 percent or less of the stem or root circumference cankered (Ostry and others 1994) Trees more severely diseased, or dead, should be removed immediately Fungus remains active on dead trees for up to 20 months (Tisserat and Kuntz 1984)

Reactive Measures Fungicide has been shown effective against butternut canker (Srivastava and others 2005) Armicarb 100 at concentrations of 0.3 percent sprayed on Can be used on valuable trees

Reactive Measures Potentially resistant pure butternut trees have been found Generally of the rare phenotype with dark bark resembling that of Juglans nigra (Michler and others 2006) DBH>10 inches No cankers Diseased trees within 100 ft. (Ostry and others 1994) Seed should be collected Plant where natural regeneration is not adequate Plant where resistant trees are not found Photo: Casey Jennings

Reactive Measures Producing resistant trees using hybrids with the Japanese walnut (Juglans ailantifolia) is one possible option (Michler and others 2006) Existing hybrids nearly indistinguishable from pure butternut Greater resistance and more vigorous trees Some (Huang and others 2008) view these hybrids as a threat to the genetic purity of the species Genetic engineering another option (Michler and others 2006) Could have issues with public acceptance and government regulations Attempts should first be made with pure butternut

Conclusion Butternut is an uncommon but valuable tree Butternut is threatened by butternut canker Butternut canker was probably introduced to North America Some resistant trees have been found, offering hope the species will not be lost

References Broders, K.D., and G.J. Boland. 2011. Reclassification of the butternut canker fungus, Sirococcus clavigignenti juglandacearum, into the genus Ophiognomonia. Fungal Biology 115: 70 79. Broders, K.D., Boraks, A., Sanchez, A.M., and G.J. Boland. 2012. Population structure of the butternut canker fungus, Ophiognomonia clavigignenti juglandacearum, in North American forests. Ecology and Evolution 2: 2114 2127. Farlee, Lenny, Woeste, Keith, McKenna, James, Weeks, Sally, and Michael Ostry. 2009. A forest manager s guide to butternut. Northern Journal of Applied Forestry 26: 9 14. Halik, S. and D.R. Bergdahl. 2002. Potential beetle vectors of Sirococcus clavigignentijuglandacearum on butternut. Plant Disease 86: 521 527. Katovich, S.A., and M.E. Ostry. 1998. Insects associated with butternut and butternut canker in Minnesota and Wisconsin. Great Lakes Entomologist 31: 97 108. Kuntz, J.E., and V.M.G. Nair. 1982. The role of hyphal pegs in spore dissemination by Sirococcus clavigignenti juglandacearum. Phytopathology 72: 1137. Michler, C.H., Woeste, K.E., Ostry, M.E., Meilan, R., Pijut, P.M., and D.F. Jacobs. 2006. Improving disease resistance of butternut (Juglans cinerea), a threatened fine hardwood: a case for single tree selection through genetic improvement and development. Tree Physiology 26: 121 128.

References Ostry, M. E., M. E. Mielke, and R. L. Anderson. 1996. How to identify butternut canker and manage butternut trees. USDA Forest Service, North Central Experiment Station, Northeast Area State and Private Forestry HT 70 Ostry, M.E., Mielke, M.E., and D.D. Skilling. 1994. Butternut: Strategies for managing a threatened tree. USDA, Forest Service, North Central Forest Experiment Station General Technical Report NC 165. Ostry, M.E. and M. Moore. 2007. Natural and experimental host range of Sirococcus clavigignenti juglandacearum. Plant Disease: An International Journal of Applied Plant Pathology 91: 581 584. Rink, G. 1990. Butternut. Pp. 386 389 in R.S. Burns and B.H. Honkala (eds). Silvics of North America, Vol.2, Hardwoods. USDA, For. Serv., Agric. Handb. 654. Srivastava, K.K., and M.E. Ostry. 2005. Efficacy of Armicarb 100 against Sirococcus clavigignenti juglandacearum. Indian Journal of Forestry 28: 162 163. Tisserat, N., and J.E. Kuntz. 1983. Longevity of conidia of Sirococcus clavigignentijuglandacearum in a simulated airborne state. Phytopathology 73: 1628 1631. Tisserat, N., and J.E. Kuntz. 1984. Butternut canker: development on individual trees and increase within a plantation. Plant Disease 68: 613 616.