[Arid_gardener] Yellow citrus leaves

[Dick]

Paul, I have a lush pink grapefruit tree with at least two hundred very sweet fruit from a tree that was 5 years old when I planted it 30 years ago. If the overall hue of your foliage is pale or yellow, the tree probably needs nitrogen. I have never used any nutrient except Ammonium sulfate 21-0-0 because someone from the U of A Maricopa County Cooperative Extension informed me in1995 that the only critical components deficient in this desert was nitrogen derived from organic compounds and the sulfer in the fertilizer was useful to counteract the alkalinity typical of desert soils and our water. Additionally, I have aging but healthy Sweet lemon, Tangerine and Robinson Naval and Pommelo trees.

I believe your irrigation cycles are way too frequent according to my own practices, at least. 

In the summer, I deep water only at the drip line every two weeks and monthly when the soil is about 65 and colder. I use a soil probe to be sure that water has soaked at least 3 feet deep in a shallow trench at the drip line around the tree. I don't water again until I find dry soil at least three inches into the soil in that same trench but I am careless about my irrigation schedule and often forget. But, if I get pennetration of at least three feet deep, I don't believe timing is as critical and I pay close attention to the folliage; A slight limp and loss of luster tells me the tree is thirsty and I respond soon to correct that deficiency.

This dialogue should prompt response from other Master Gardener Volunteers but if any of this is confusing or needs further explanation, don't hesitate to inquire or contradict so that I too can learn.

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



  At 06:18 PM 7/3/2007, paul christensen wrote:

    I was wondering why my 2 ruby red grapefruit trees' leaves are turning yellow?  They were planted in the spring of '06 and then suffered through the harsh frost of last winter.  I covered them up and thought they had survived ok.  The leaves grew back and were nice and green.  Now with the AZ temps over 110 degrees I am deep watering once a week in addition to the automatic shorter waterings from a drip system 3X a week.  Am I over watering?  I have not fertilized them.  The leaves have recently turned yellow.  Please advise what I need to do -or not do.  Thanks for your information and help.
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