[Arid_gardener] Question from Home-Hort WWW page

[Dick Gross]

Laura, I don't know for sure what has caused this problem but I have a hunch it may be related to sunburn. The natural growth habit for Citrus is to cascade foliage all the way to the ground shading all the bark except for brief windows that move as the sun traverses the sky. The direct exposure is only momentary without damage.

The custom by homeowners is to trim citrus high enough to drive a semi truck beneath its branches without scratching the paint. Sunburn destroys the bark as evidenced by front yard trees all over the Valley. The condition interferes with the normal flow of fluids through the tree's vascular system. Without that feeding system, carbohydrates manufactured in the foliage can't reach the roots and nutrients adsorbed by feeder roots can't feed the foliage. At least, that is the approximate process, as my mind percieves it, causing the plant or tree to languish. The bark is one of the tree's vital organs without which it cannot survive. 

Branches exposed to full sun for extended periods can be fully protected by slapping on a coat of white latex paint that reflects enough heat for full protection.

I don't know enough about your particular situation to say positively that the above is your problem or the only problem but one or two of the thousand or so Master Gardeners in this valley  should weigh in on this common citrus hazard in the Salt River Basin

Dick Gross, Master Gardener Volunteer
Maricopa County Cooperative rextension.
.
----- Original Message ----- 
From: <lauralaurao at yahoo.com>
To: <arid_gardener at Ag.arizona.edu>
Sent: Monday, June 18, 2007 9:10 PM
Subject: [Arid_gardener] Question from Home-Hort WWW page


> Laura
> 85033
> lauralaurao at yahoo.com
> 
> My grapefruit tree is oozing out orangey sap from the trunk and some branches.  The sap turns a crystalized almond color when it falls off.  
> 
> We have lived here twelve years and this has never happened.  I don't know the age of the tree.  
> 
> Otherwise, the tree has new growth and seems to be healthy.  This has been happening for a few months now.
> 
> Could you tell me what this might be.
> 
> 
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