Ash Yellows in Wisconsin and Minnesota
Kathy Kromroy,
Kyoko Scanlon & Jonathan Osthus October 16, 2018 What is ash yellows?
• Disease – ash, lilac
• Phytoplasma • Wall-less bacteria • Obligate parasite • Described 1967 • Formerly MLOs
• Plant phloem, insect vector Phytoplasma bodies in the upper sieve elements • Candidatus Phytoplasma Assunta Bertaccini fraxini Phytoplasma diseases
• Impact – partial to total loss
• Disrupt growth – rate, form, function, dominance
• “Yellows”
• Woody plants – branch dieback, decline
• Other abiotic, biotic factors - similar Phytoplasma diseases
Aster yellows
https://ipm.illinois.edu/diseases/rpds/903.pdf
Spirea stunt Phytoplasma diseases
Grapevine yellows Apple proliferation
https://www.apsnet.org/ meetings/topicalmeetings/ NPDRS/Documents/2013/ Loschi. DBADPU Udine, Italy.
Michael Maixner, Julius Kühn-Institut (JKI)
Fiona Constable (CABI, 2007). S. Malembic-Maher, INRA Frederico Bondaz, Pl. Prot. Unit Val d’Aosta (IT) Why talk about ash yellows?
•Present in region
•In Minnesota – 2 reports •Reports of dying, declining ash - not EAB
•Impact?
•Concern Ash Yellows in Wisconsin
•First confirmed in Wisconsin on white ash in 1987 •A survey in 1990 (IL, IA, MO, WI) (Luley et al. 1992) Microscopic technique (DAPI staining test) → Molecular technique (PCR test) •Sample submission since 2005 •Currently, ash yellows is found in 32 counties
DAPI = 4’,6’-diamidino-2phenylindole Ash Yellows in Wisconsin
Ash yellows impact case study (Richland County) • One mixed hardwood stand with pole-size white ash trees •13 trees were marked and annually monitored from 2009 and 2018 •6 out of 10 tested trees were positive for phytoplasma by PCR test
•EAB was confirmed in 2018 Ash Yellows in Wisconsin
Ash yellows impact case study (Richland County)
Confirmation included trees with early crown symptoms
Crown dieback rating 30 % Crown dieback rating 35 % Ash Yellows in Wisconsin
Ash yellows impact case study (Richland County) •One tree was negative in one year and positive in the following year with no apparent change in crown condition
PCR test negative (2011) PCR test positive (2012) Ash Yellows in Wisconsin
Ash yellows impact case study (Richland County)
AY-positive trees could live for years (DBH 7.5”)
2010 (tested positive) 2015 2017 (tested positive) Ash Yellows in Wisconsin Ash Yellows in Wisconsin
Broom on basal sprouts/epicormic branch of dead trees
Broom on epicormic branch tested positive Basal sprout tested positive Ash Yellows in Wisconsin
Stump sprouts were confirmed with Phytoplasma
Stump diameter 5”
Stump diameter 4” Stump diameter 7.5” Phytoplasma in Wisconsin
Species tested positive with phytoplasma Acer rubrum (red maple) Carya ovata (shagbark hickory) Carya condiformis (bitternut hickory) Corylus sp. (hazelnut) Fagus grandifolia (American beech) Fraxinus pennsylvanica (green ash) Fraxius Americana (white ash) Fraxinus nigra (black ash) Juglans cinerea (butternut) Juglans nigra (black walnut) Morbus sp. (mulberry) Picea glauca (white spruce) Quercus bicolor (swamp white oak) Syringa sp. (lilac) Ulmus sp. (elm) Phytoplasma in Wisconsin
Questions •Are confirmed non-ash species infected with the same species of phytoplasma that is found on ash? → Sequencing •Can phytoplasma from ash infect other tree/plant species? •What impact does phytoplasma cause to newly confirmed species? •Can ash stump sprouts and/or other hosts act as reservoirs for the pathogen? Ash yellows in Minnesota
• Objective
• Survey approach
*Brooms
• Testing
• 8 of 23 Positive for AY Ash yellows in Minnesota
Parameter 8 AY Positive 15 AY Negative Growing location Urban, Rural DBH (inches) 6 to 20 6 to 25 Species Green (Black, White), Crown class (1 healthy, 5 Dead) 2 to 5 1 to 5 Overall stunting Other stressors Yes, No Other symptomatic ash trees Ash yellows in Minnesota
Parameter 8 AY Positive 15 AY Negative Exit holes Bark splits Woodpecker damage
Insects present Yes, No Yes, No Small leaves Yellow leaves Malformed leaves Epicormic branching Yes Yes Brooms Yes Yes Positive for ash yellows – St. Paul Positive for ash yellows – St. Paul Positive for ash yellows – Northwest MN Positive for ash yellows – Southwest MN Negative for ash yellows – West central MN Negative for ash yellows – West central MN How important is ash yellows?
Quantitative impacts?
If all the ash trees are going to die from EAB?
Does it’s presence alter EAB management? • Are the non-ash species infected with the same phytoplasma that is found on ash? *Walnut •What impact does phytoplasma have on these other plant species? •Can ash stump sprouts and/or other hosts act as reservoirs for the pathogen? THANK YOU
Brett Arenz, Jennifer Flynn, Ben Lockhart - University of Minnesota
Angie Ambourn, Nate Goodell, Chris Mallet, Patrick Walrath, Marissa Bendickson - MDA
John Nielsen, Dale Parker – landowners
University of Wisconsin Plant Disease Diagnostics Clinic
WI DNR Forest Health Team