[Arid_gardener] RE: Citrus Tree Care in the Valley

[Carolyn Hills]

You are in luck, as there are some fantastic resources available on citrus
care in Maricopa County. "Desert Landscaping for Beginners", a book written
by Maricopa County Master Gardeners, has a 22-page chapter dedicated to
citrus care here in the Valley. In addition to answering your questions, it
also covers many other important topics relative to keeping citrus healthy.
To get more info on this book and other Maricopa County Master Gardener
publications, check out:

http://cals.arizona.edu/maricopa/garden/html/pubs/mgpress/mgpress.htm

Also, check out:

http://ag.arizona.edu/maricopa/garden/html/pubs/pubs.htm

for great free horticulture publications put out by University of Arizona
for Maricopa County. Six of the pubs listed are about caring for citrus.

Below are some quick answers to your questions, but I'd highly recommend
looking at the other resources I've listed, as they answer a lot of
questions you will no doubt have in the future as you care for your citrus
trees.
 
WHEN ARE LIMES READY TO PICK? As with any citrus, limes are ready to pick
when they taste good to you. Generally, the longer the fruit stays on the
tree, the sweeter it will taste. Some limes, especially the Mexican Lime
commonly sold by nurseries here, may produce year-round.

GRAPEFRUIT TREE NOT PRODUCING FRUIT: A combination of things can result in
low fruit production on citrus trees. 

* Hopefully, you did your research in advance or purchased from a reputable
local nursery and planted a variety that does well here in the low desert.
Check out this pub from U of A for recommended varieties:

http://cals.arizona.edu/pubs/garden/az1001.pdf

* Citrus trees usually need to be 3-5 years old before they start to
produce. If the tree is young and looks healthy, don't worry.

* Also, if a tree produced a LOT of fruit last year, it may have to take a
season off to recover, so will produce very little fruit this season.
Commercial growers remove fruit that is over burdening their trees because
they need to have a consistent harvest year-to-year.
 
* Other factors which may inhibit fruit production are improper fertilizing
and improper watering (covered below). Trees will dump any fruit they don't
have the energy to support.

FERTILIZING CITRUS: Any good commercial citrus fertilizer (available from
your local nursery) will be fine, but the amount of fertilizer to apply
depends on (1) how much nitrogen is in the fertilizer and (2) how many years
your tree has been in the ground and size of the tree, and (3) the type of
fruit. How to apply the fertilizer depends on what type you use. Follow the
instructions on the package. You should be applying fertilizer 3 times per
year, one-third in Jan/Feb, one-third in April/May and one-third in
Aug/Sept.
 
WATERING CITRUS: Some people try to add their citrus trees to their existing
drip irrigation systems (which can be done), but fruit trees require a
different watering cycle than most landscape shrubs. Citrus trees usually
benefit from deep watering once/month in non-summer months and every two
weeks during summer. They need deep watering to leach salts below the root
zone (our local city water sources are uniformly salty). Most of the stuff
I've read says you should water down 2-3 feet, which means you should be
able to push a 2-3 foot rod (like a piece of rebar) down that far without
getting much resistance. 

On almost any tree, the roots extend just about as far out as the canopy of
the tree. The roots at the very end, just below the canopy, are called
"feeder roots". These are the roots that bring water and nutrients up to the
leaves. A lot of people have trees installed by landscapers who put one or
two drippers at the base of the tree, which might be okay for the first few
months. As the tree grows, the roots extend out and, if the tree is only
getting water at the trunk, the tree will suffer and probably die. 

It's very easy to make sure that the feeder roots get the water they need.
You can dig a small trench (doughnut) around the "drip line" (the line just
under the canopy), and just water that. You will need to extend your
doughnut each year to accommodate the larger size of the tree until it is
fully grown. The doughnut does not have to be more than a few inches deep,
as long as water is able to get around the whole circumference.

I am a non-scientific waterer, so tend to just keep a hose on very low drip
and leave it on each citrus tree for 2-3 days and then move over to the next
tree. It seems to work for me!

If you see your citrus tree leaves curling vertically, that means they are
stressed for water. If you see a bit of brown around the outside edges of
the leaves, that means they have "salt burn". Trees respirate by taking
water up from their roots and out through their leaves, so infrequent, light
watering can leave salt deposits on the outside edges of the leaves, burning
them. That's why less frequent, deep watering is recommended. "Desert
Landscaping for Beginners" has good tables to help you figure out watering
schedules for your trees. In my opinion, correct watering is the most
important factor for your citrus trees' health here in the low desert.
 
Hope this helps!
 
Carolyn Hills
Maricopa County Master Gardener Volunteer

-----Original Message-----
From: arid_gardener-bounces at CALS.arizona.edu
[mailto:arid_gardener-bounces at CALS.arizona.edu] On Behalf Of
ruggieroln at cox.net
Sent: Sunday, August 19, 2007 3:46 PM
To: arid_gardener at Ag.arizona.edu
Subject: [Arid_gardener] Question from Home-Hort WWW page


85028
ruggieroln at cox.net

Citrus questions:

When are limes ready to pick?  Mine seem ready now (August)

I have a grapefruit tree planted last fall that has only two fruits that are
small and don't seem to be growing although the tree looks healthy.  A
nearby lime tree planted at the same time is loaded with fruit.  What should
I do to increase fruit on the grapefruit?

When should citrus be fertilized?

Both trees are on an automatic drip irrigation system.  Is that okay for
citrus?

Thanks for your help.


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