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I have two new flowering pear trees that are being used as breakfast, lunch and dinner. I am not sure what is eating them the leaves have large scallops taken out of them. The lower branches have been affected more than the top ones. Any ideas?

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A

Without actually seeing the damage to your leaves it is difficult to give you an accurate diagnosis of what is happening.  By your description there may be two different types of insects causing the notches in your pear tree leaves.  Properly identifying what is causing the damage can help you decide on what control methods to use.  

The first type of insect that causes damage like you described is a root weevil.  Two common varieties that could be damaging your pear trees are Lilac Root Weevil (Otiorhynchus meridionalis) and Strawberry Root Weevil (Otiorhynchus ovatus).  These insects are particularly hard to find on your plants because the adults hide during the day, only feeding at night and the larvae live in the root zone of the plant feeding on the tissues there.  Because they can be difficult to find you could create a trap by placing a fold of burlap around the base of the tree or by burying a paper cup at soil level.  This will allow you to collect a specimen.  If it is root weevils a non-chemical method of control would be the use of commercial sticky traps placed in a protected area either in or near the tree.   If you choose to use a chemical insecticide use one that is a PyrethroidThe following link has more information on root weevils http://www.ext.colostate.edu/pubs/insect/05551.html

 

The second type of insect that may be causing the damage is Leafcutter bees.  They are a native species of pollinators that use the portion of the leaf that they have notched out in rearing their young.  These insects are not pests and control practices are not recommended because they are very beneficial in helping to pollinate our crops and ornamental plants. 

 

By following this link you can see pictures that show what typical damage of both Root Weevil and Leafcutter Bees looks like. 

http://utahpests.usu.edu/ipm/files/uploads/HortAdvisories/2007/Hort-IPM-06-27-07.pdf

 

To help provide you with a better diagnosis of what is happening to your pear tree leaves you can bring a sample into the USU Extension Office located at 2001 S. State Street for identification.  Our office hours are Monday through Friday 8:00 am to 5:00 pm.

 

Precautionary Statement: All pesticides have benefits and risks, however following the label will maximize the benefits and reduce risks. Pay attention to the directions for use and follow precautionary statements. Pesticide labels are considered legal documents containing instructions and limitations. Inconsistent use of the product or disregarding the label is a violation of both federal and state laws. The pesticide applicator is legally responsible for proper use.

 

Posted on 15 Oct 2007

Heidi Wayman
Horticulture Intern, Salt Lake County

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