[Arid_gardener] Re: Mt leaf tips are turning brown, and leaves drop off. What am I doing wrong with my avocado?

[Dick Gross]

If salts are dissolved in the water, it travels up through the plant 
vascular system to the foliage where it packs into leaf cells starting at 
the tip and traveling up the edges killing the cells as it goes. You can 
track the progress by following the browning from the tip and up the fringes 
until a nearly dead leaf falls. The salt cannot evaporate, of course. The 
more leaf cells that are dead, the less photosynthesis there is to 
manufacture carbohydrates and the plant progressively starves itself to 
death. You can continually flush the salt compounds through and below the 
root zone but the level in the root zone will never be below that existing 
in the water itself. I assume some or most chemical fertilizers, being 
themselves, may add to the problem. Tell me if I am wrong. I use only 
Ammonium sulfate assuming the sulfur might give me a leg up in dispersing 
alkalines. I have used a product called Dispersol but didn't note any 
drastic change if I knew what to look for.

A 3 to 4 inch layer of mulch in the basin will effectively prevent 
evaporation from accumulating salts in the root zone. In some plants more 
susceptible to salt, you can't control salt burn entirely but these tactics 
can maintain levels that many plants can live with. Avocados are very 
susceptible to salt. Flushing and mulching are the best you can do as far as 
I have been able to determine. Maybe a reader can come forth with some magic 
he or she would willingly share with this forum.

Dick Gross, Master Gardener Volunteer
University of Arizona
Maricopa County Cooperative Extension.

bcc: Arid Gardener

----- Original Message ----- 
From: "Kentfield, Alex (SBT US)" <alex.kentfield at siemens.com>
To: <info at crfg.org>
Sent: Monday, October 30, 2006 10:28 AM
Subject: Mt leaf tips are turning brown, and leaves drop off. What am I 
doing wrong with my avocado?


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