[Arid_gardener] Re:

[Dick Gross]

Ed, what kind of fruit trees? I will assume they are citrus. Find out where 
the University of Arizona Yuma County Cooperative Extension is located and 
visit them. They probably have brochures covering every phrase of home fruit 
production.

Keep in mind that plants shed leaves for the same reasons that people 
routinely shed skin and hair. Some of it is heathy and natural but 
determining what degree is abnormal is the fine tuned judgement a gardener 
develops with trial and error killing a lot of plants along the way. Leaf 
yellowing can be a reaction to both climatic and cultural conditions--too 
much water, too little, disease, insects and divine intervention but citrus 
thrives in Yuma with little human influence while remembering their personal 
likes and dislikes, i.e., grapefruit likes dry air and Naval oranges like a 
humid climate best but you can get a decent crop from either variety in 
either place with the right care.

To the best of my knowledge, that whole Yuma valley is comprised of Colorado 
river alluvium and and drainage is maybe better than what might be ideal; a 
tendency to leach nutrients from the root zone the downside. If your trees 
are on the fringes of that zone, my observations might be off target.

The feeder roots are abundant in a zone around the drip line that is an 
imaginary line in the ground defining the average reach of foliage. Unless 
it is necessary for some reason for you to flood irrigate, make a shallow 
trench belting the tree with the drip line being in the middle of the 
trench. That is the area where fertilizer and water should be applied to a 
depth of at least 3 feet for the best effect.

Put a hose end in your trench and adjust the flow to maintain a constant 
water table a quarter to an inch deep all arount the tree. Using a soil 
probe, shut the water off when the probe can be inserted straight down to a 
depth of 3 feet in several places around the tree. That depth will be 
reached very quickly in sandy porous soil or it could require several hours 
or more. Here in Phoenix on my trees, I often let the water trickle ten to 
15 hours  If the fertilizer is applied at the outset in very porous soil, 
most of the nutrient could be washed through the root zone with little 
effect of feeding the tree. Your local nursery expert or the Yuma 
Cooperative Extension can help you adopt a pattern best for your soil.

If the soil is quite dry, I irrigate for a couple hours before pouring the 
prescribed amount of 21-0-0, Ammonium Sulfate, in a bead in the center of 
the trench all the way around. Continue to irrigate until saturation has 
reached that 3 foot depth. Don't irrigate again until the trench is quite 
dry two or three inches deep. On the average, in this area, that is every 
seven to ten days in summer and monthly or longer when the high temps are 
below 75 degrees.

I irrigate when I remember and by habit but usually by detecting a slight 
wilt and a lack of luster of the foliage.

If irrigation is deep, the system has a much greater resistance without 
stress to daily fluctuations. A tree under duress is much more susceptable 
to disease and insect attack.

I hope this novice's approach to your question is adequate, Ed. If not, 
respond with more parameters and see if we can get a more corporate 
response.

Any civil contribution to this question from anyone is, however, 
invited--and welcome, of course.

Dick Gross, MGV  U. of A.  MCCE

Bcc: Unspecified recipients.


----- Original Message ----- 
From: "Ed Keibler" <Keiblerpop at webtv.net>
To: <rkgross3 at cox.net>
Sent: Saturday, July 22, 2006 9:09 PM


> Dear Sir
> I live in Yuma and have a couple fruit trees. Could you tell me how
> often I should water them in this heat---and why some leaves turn yellow
> in this heat.
>             Thank You  Ed Keibler
>
>
>
>
>