[NAFEX] lime sulfur(apricot tree rescue)

Dennis Norton dmnorton at royaloakfarmorchard.com
Thu Apr 6 18:24:25 EDT 2006

Canker, gumosis or bacterial canker are common infections in stone fruits, 
especially peach and apricot.  Bacterial canker is, in my opinion, the 
worst.  But any stone fruit tree that has gum oozing (gumosis) may not 
necessarily have a disease, although it usually does.  The oozing gum is 
also the tree's way of protecting itself from any bark damage and can be 
quite common on peaches and apricots.  Unfortunately the gum is usually a 
sign of progressively worse problems and it is hard to know without lab 
tests.  The University of Wisconsin has a great pathology lab and the costs 
are minimal. You can find them at  http://pddc.wisc.edu/index.html or google 
"plant disease diagnostic clinic" for your state's clinic.

If it is gumosis, there is no chemical control for the disease.  Destroying 
or removing dead trees and prunings can be helpful in reducing inoculum.  It 
can spread through pruning shears, rain, weeds or wind.  A tree can survive 
for several years with the disease, but will eventually lose its scaffolds 
one by one as they become infected.  If you have trees with gumosis, prune 
them in late spring as the wounds can heal faster and not be as likely to 
pick up more infection from a blowing rain storm, etc.  Disinfect the shears 
after each cut with bleach or vinegar so as not to spread the disease 
through the shears.  If there is dead wood on the trunk and the tree is a 
young tree, you can cut out the dead wood and seal with Tanglefoot 

If it is bacterial canker, use the same techniques as gumosis, but also 
spray with copper-containing compounds for control.  Spray just before bud 
swell as copper can injure stone fruit crops and do not use more than one 

If there is leucostoma canker present with the gum, then get on your knees 
and pray!

How do I know all of this?  Been there, done that!  With over 1,000 peach 
trees and 100 apricot trees as well as plum and aprium, we have experienced 
it all.
Hope this may help someone.

Dennis Norton
Royal Oak Farm Orchard
----- Original Message ----- 
From: "tanis cuff" <tanistanis at hotmail.com>
To: <nafex at lists.ibiblio.org>
Sent: Thursday, April 06, 2006 2:13 PM
Subject: Re: [NAFEX] lime sulfur(apricot tree rescue)

> Arboriculture answer, rather than an apricot-grower's:  this probably 
> won't save your tree.  It is too difficult to remove all the infection, 
> maybe impossible.  And you will do lots of physical damage to the tree.
> But if you are sure to lose the tree w/o intervention, then why not?  To 
> call it a comprehensive research project, take pieces of the infected bark 
> & wood to a disease-testing lab.  First get info from them on the best way 
> to do this.  Then you can say "Tree had these infections, and I did these 
> procedures, and tree recovered/ died."  Let us know.
> ----Original Message Follows----
> From: mauch1
> Reply-To: North American Fruit Explorers <>
> To: nafex@
> Subject: [NAFEX] lime sulfur
> Date: Thu, 06 Apr 2006 15:02:45 -0400
> I have a similar problem with an apricot tree.  The tree is about 4-5 
> inches in diamter, and the visible fungi has spread to about half the 
> trunk diameter and extends from the ground into where the tree begins 
> branching.
> Observation.  I too have the white fungi, though mine looks more like 
> shelf fungi.  I believe they only came after the bark/tissue was already 
> dead.  I believe the problem started when the tree received winter damage 
> from cracking bark (warm sun followed by freezing temperatures).  The bark 
> began to ooze.  I call this 'gummosis', but I believe this was only a 
> symptom not the cause.  Possibly a bacterial infection?
> What I'm planning to do.  I kept expecting the tree to die, but its been 
> going on for 3 years like this, with the dead area gradually widening.  I 
> think the healthy remaining tissue cannot recover as the moist/dead tissue 
> is continuing to infect the healthy tissue, and the dead tissue blocks the 
> regrowth.  So unless someone has a convincing anti-argument, I'm going to 
> remove the diseased dead tissue/bark with a chisel.
> This should allow the wood underneath to dry out and not remain a source 
> of fungi.  The healthy tissue (theoretically), should be able to grow back 
> over.  Thoughts are welcome.
> Chris Mauchline
> SE PA, zone 6
> 40° 5' N 75° 51'W
> ~650 ft elevation

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