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Symptoms of Emerald Ash Borer Infestation

Tagged as: EAB, Emerald Ash Borer, emerald ash borer in Illinois

Emerald ash borer (EAB) infestations often go undetected until the trees begin to show symptoms. A tree may be infested for a year or more before symptoms first appear. The symptoms listed below may indicate the presence of emerald ash borer:

EAB D hole

Figure 1

D-shaped exit holes (approximately 1/8 inch in diameter) on the branches and trunk.  These are often found first in the upper portions of the tree.  Due to the rough texture of ash bark, the holes may be difficult to locate.

 

 

EAB ash thinnng

Figure 2 and 3

Wilting and yellowing foliage will be seen, sometimes on individual branches, sometimes throughout the crown.  This will be followed by thinning of the canopy and branch dieback.

Photo credit (Fig. 2):  Jeffrey Hahn, University of Minnesota

Photo credit (Fig. 3):  Illinois Department of Agriculture

 

EAB dieback

 

EAB gallery McHenry County IL IDA

Figure 4

Larvae tunnel distinct serpentine (S-shaped) galleries packed with excrement under bark.  Vertically split or cracked bark may occur above theses larval feeding galleries.

Photo credit: Art Wagner; USDA/APHIS/PPQ

 

EAB Wood pecker damage Minnesota Dept. of Agriculture 2

Figure 5

Jagged holes produced by woodpeckers working to extract larvae from the tree.  The tan color of these woodpecker sites stand out against the gray color of the bark.

Photo credit:  Minnesota Department of Agriculture

 

EAB Sprouting Beth

Figure 6

A large number of shoots or suckers  can grow below the dead portions of the tree, particularly at the tree base.  This usually happens when the tree has been infested for some time and a large portion of the canopy has died.

 

Updated 2012

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