Ash Trees: They
have problems!
Laura Jesse
Plant & Insect Diagnostic Clinic
Iowa State University
Ash anthracnose
• Fungal leaf
disease
• Can cause
leaf drop
Ash anthracnose
• Brown lesions on
leaves
• Curled distorted
leaves
• Management
– Rake up fallen
leaves
– Fungicides rarely
needed
Verticillium Wilt
• Fungal disease that affects many
tree species
• Symptoms appears in June - July
– Sudden wilting of leaves on one or
several twigs
– Branch or crown eventually wilts
– Decline or dieback of new twigs
– Yellowing foliage
– Sapwood discoloration
• More common on stressed trees
• Management: Remove infected
trees
Ash Decline
• Observed since
1930’s
• Primarily white and
green ash
• Unexplained
progressive decline
http://www.colostate.edu/Dept/CoopExt/4DMG/images/decline.jpg
Ash / Lilac Borer
Photo by Mark Shour, ISU
Photo by Mark Shour, ISU
Photo by Mark Shour, ISU
Ash/lilac Borer
• Symptoms
– Exit holes
– Sawdust and frass
– Swelling and cracking
• Management
– How extensive is the damage
– Three insecticide treatments
starting mid-May
– Pheromone traps available
Other Borers
• Longhorned beetles
– Redheaded ash borer
– Banded ash borer
Roundheaded borers
Emerald ash borer
Other borers
• Eastern ash bark
beetle
Photo by Mark Shour, ISU
Client Reporting a Stressed Ash Tree
1) Do you know the tree(s) are
ash, Fraxinus species?
http://www.extension.iastate.edu/pages/tree/key.html
http://emeraldashborer.info/files/E2942.pdf
2) Does the tree have thinning
crown? Are branches dying?
• How old is the tree?
• How long has client
observed the problem
– Several years or very
recently
• Age of tree
• Appearance of
individual leaves
http://www.snr.missouri.edu/images/forestry/emeraldash/thincanopy.jpg
3) Are there suckers /
watersprouts growths on the
trunk?
4) Are woodpeckers working on
the tree?
•Are there S-shaped feeding galleries under the bark? Near top of tree
Epicormic shoots and
woodpecker damage
https://www.msu.edu/~lindellc/images/eab%20damage.JPG
4) Loose bark with S-shaped
feeding galleries under the bark?
Starts near top of tree.
Credit: M. H. Shour, ISU Extension
5) Are there D-shaped exit
holes (1/8th inch diameter)?
If you cannot eliminate EAB
as a possibility or client
wants a diagnosis
• Send samples to:
Plant & Insect Diagnostic Clinic
327 Bessey Hall
Ames, IA 50011
• Send digital images of the tree to
insects@iastate.edu
Client reports they have caught an
adult beetle
• EAB is most likely to be detected in an
ash tree in the larval stage. However,
many reports will involve a client seeing
suspected adults.
– If the client has not collected a specimen
• Show them pictures of look-alike insects to see
if they think maybe it was something besides an
EAB.
• Ask them to try to capture a specimen next time
they see one.
http://www.extension.umn.edu/distribution/horticulture/M1242.html
• If the citizen has the insect
–Mail the insect to:
Plant & Insect Diagnostic Clinic
327 Bessey Hall
Ames, IA 50011
–E-mail pictures to
insects@iastate.edu
Thank You!
Plant & Insect Diagnostic Clinic
327 Bessey Hall
Ames, IA 50011
515/294-0581
insects@iastate.edu
ljesse@iastate.edu