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June 2011


It’s time once again to discuss Crown borer. 


The peachtree borer (GPTB), Synanthedon exitiosa, is a  striking clear-winged moth with yellow and steel-blue body markings. The adults of these insects have from one to four yellow-orange stripes across the abdomen, depending upon species and sex. GPTB is a pest of stone fruit, principally peach.  The GPTB enters the tree near soil level and does not require the presence of wounds or breaks in the bark for entry. This species pass the winter as borers (worm like) inside the tree, and in the summer emerge as moths that lay eggs on or in the trunk during the summer.  The  GPTB doesn’t show up until late June early July; and stays active (laying eggs) through September. When the borer stage hatches, the GPTB tends to crawl down the tree to soil level and burrow in there.  Some GPTB larvae take two years to develop, so any control measure a grower would elect will require repeating for at least 2–3 years.  Injury is caused by larval feeding on the cambium and inner bark of the trunk close to the soil level.  Occasionally, larger roots are also attacked by GPTB.  Areas attacked often have masses of gum, mixed with frass, exuding from the bark at or just below the soil level.  All ages of trees are injured. Young trees are at times completely girdled.  Older trees are often so severely injured that their vitality is lowered and they are rendered especially susceptible to attack by other insects or by diseases.  The two forms of control for this pest are trunks sprays applied several times during the summer and mating disruption using pheremones. 


Crown borer is out and active in Mesa county and the lower elevations of Delta county.  If your program includes the use of Isomate P for mating disruption, it’s time to hang it in your orchard.  The life of this product is sufficient to cover through the end of the season. 


If you plan to apply trunk sprays the first application should be done in early July.  This pest remains active all summer and into the fall.  One application in July will not protect your orchard for the season!  A second spray in early August is advised.  Re-entry issues and harvest pressures provide enough reason to use mating disruption for the foundation of your control program.


Over the last several years I’ve inspected peach blocks that were collapsing from crown borer damage.  Don’t let this pest establish itself on your farm!  Make it a regular habit to inspect tree trunks at the soil line.  Scrape the ground at this juncture with your boot and look for signs of feeding.


Give me a call if you need help putting a control program together.



Those who expect to reap the blessings of freedom, must, like men, undergo the fatigue of supporting it.  ~Thomas Paine



Freedom is never given,  It is won!




Enjoy your fourth of July!

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