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Plant Diseases/insects inside weeping cherry trunk


QUESTION: Help! My poor weeping cherry, which is about 20 years old started to look bit sad, the leaves have died, I put this down to our exceptionally hot summer, I am in Victoria Australia. Cut the branches off and there is a big hole at the top of the trunk that has been eaten by something, there are little holes in the inside where the wood is like paper, can't see any bugs tho. Can't find anything like this on net. Is my baby past help and will my other cherry which is about 4 meters away be at risk. Some brown leaves but can't see any wounds. Many thanks

ANSWER: Dear Gilly, I am very sorry to hear about your cherry tree.  What you have is borers.  Borers are strange things because they come in two types.  One type is usually a large beetle often with long antennae.  The other type actually looks like a moth or a bee, they are usually striped insects with clear wings.  The problem with borers is that you don't often see them.  Usually all you ever see is the damage that they leave behind, which is dead limbs and trees, dying leaves, holes in the bark and bits of sawdust caused by the chewing and excreting of the borer larvae.  Here's the whole plan for controlling the borers.  Carefully inspect both trees, being especially careful to trim off any loose sections of bark and dead limbs, and any areas that have dead areas in them, try to trim the dead area out and apply pruning paint.  Clean up the area around the trees thoroughly to prevent any insects that are overwintering or hiding in the leaf litter.  Then spray both trees thoroughly with Spinosad, the active organic ingredient in some pesticides.  Look for Spinosad under active ingredients on the chemical label.  This will not affect fruit trees, and will not affect any beneficial insects.  It ONLY kills the insects which are eating on the trees.  Also look for any areas of dripping sap on the trunk; the hole that the sap is coming from is the site of a borer.  I have actually seen people with a thin wire poke inside the holes and come out with the worm, but that is fairly difficult and time consuming.  I am not very familiar with pesticide regulations in Australia but let me know if you are unable to find Spinosad.  You should be able to find a good borer spray.  I hope this information helps.  Good luck, Melissa

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QUESTION: Many thanks for your quick response, do you by any chance know of any homemade pesticides for this problem, oo cos the pesticide u mention kill all types of borers. Thanks :-)

Dear Gilly, Sorry for the delayed reply, but the Spinosad would definitely be the way to go on treating this problem.  Spinosad is only going to kill the bugs that come to eat where you spray.  If a bug lands on a sprayed tree, nothing will happen to it, but if it starts eating the leaves or chewing through the bark, it will die.  Likewise, any beneficial bugs that come to eat the bugs that are eating the tree will also be fine.  As long as they aren't eating the tree, they will be fine.  All borers are very destructive to trees, although most borers have a specific species or type of tree that they feed on.  There really aren't any homemade pesticides that will treat this problem.  They used to paint the bottom 5 feet of trees to keep borers off, but since your tree has already suffered damage, it probably won't do a great deal of good, and it isn't a great remedy.  I hope this information helps, but please write back if you have further questions.  Melissa

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Melissa Johnston


Plant diseases, landscaping, tropical plants, roses, herbs, plant care, grafting, horticulture, plant identification, anything about plants I can likely answer.


35 years experience in various plant businesses, 1984 Certified Texas Master Gardener.

Master Gardener Association of Texas charter member

none as of yet, but I have a plant q&a book I am in process of submitting.

Magna cum laude graduate of Texas A&M, 1978

Awards and Honors
Plant growing awards, highest grade for Texas Master Gardener graduates.

Past/Present Clients
Past member of and was very highly rated. Owned landscape company in the past, Almost Paradise, and was very successful despite little equipment, no help, and no advertising. Lived well for two years until 9/11.

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