Unthrifty apple trees #167820 - Ask Extension

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Unthrifty apple trees #167820

Asked February 23, 2014, 5:48 PM EST

We have 2 dwarf apple trees. One (the short curved tree within the plastic ring) always has leaves and a few flowers, but has never "taken off". The other is covered with lichen. Today I discovered black patches and splitting bark. Both trees were purchased from reputable mailorder
 nurseries 10 years ago. Is there a diagnosis and cure for either tree?

Montgomery County Virginia

Expert Response

Hello Fellow Apple Tree Owners, Your pictures illustrate a very concerning problem with at least the larger of your two trees.  The blackened area with splitting bark appears to be the remnants of the bacterial disease called Fireblight. This disease if very destructive as it progresses into the transport system of the tree and rapidly spreads into the structures necessary for nutrient and water transport.   The tree unable to support nutrient flow begins a slow death.  Unfortunately, Fireblight is bacterial and unable to be treated with much success once a girdling lesion is present (like pictured).  We typically spray preventative sprays in commercial orchards during the month of April; however, your tree appears to infected at its core.  Our Extension website www.ext.vt.edu has a search box that will provide you excellent Fireblight information.As for the second spindly tree, the lichens (while not hurting the tree) indicate to me that the tree is stressed and bark shrinkage has occurred.  This is an indicator of poor root growth or other transport related problems.  Probably over the course of several years, both trees have had difficulty with transporting water and nutrients and while stressed, became even more susceptible to other disease pressures.  A growing tree is a healthy tree, fertilize NOW with a 10-10-10 or complete garden fertilizer.  Two full cups of fertilizer sifted out around the dripline or outer root zone of the tree.  Follow again prior to June 1st with a second application and push this remaining tree for new growth.As for your larger tree, I am deeply concerned about its survivability and would suggest its removal as is will serve to infect other apple and pear trees in the vicinity.  The alternative is to cut 8-12 below the blackened trunk area and dispose of the upper portion of tree.  The resulting blunt cut will see vigorous water sprouts emerge that may then be trained into a new central leader and limb system.  This will take time and effort over the next three seasons.  A copper spray (possibly mixed with a horticultural oil) will also work to keep lingering Fireblight bacteria from hiding in bark fissures and crevices and becoming a problem when 70 degrees days and spring rains return.Please contact me at my regular email address jmvest@vt.edu if you have additional concerns or with to keep me posted on your "doctoring" process.Kind regards, JON
Jonathan Vest Replied March 12, 2014, 2:32 PM EDT
Jonathan,
thanks for your detailed and empathetic response! I will follow your directions this weekend. Good to hear from you again

ernie bentley
pilot, va
The Question Asker Replied March 12, 2014, 4:45 PM EDT

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