Weekly Express-News Article
By Calvin R. Finch, PhD, SAWS Water Resources Director, and Horticulturist
Saturday, January 5, 2008
“Selecting and Planting Fruit Trees”
This time of the year, area retail nurseries receive their
shipment of apples, peaches, plums, and pears. There are several practices that increase the
chances that you will be successful with your planting of fruit trees.
Select the varieties that are recommended for the area.
They are well adapted enough to prosper in our conditions.
Among the characteristics that
are important are chill requirement and disease resistance.
Peaches, apples, and plums will all grow in San Antonio if a variety is selected
that requires about 500 hours of weather between 32° and 45° F in
the winter. Some varieties
that meet the requirements are Junegold and La Feliciana peaches;
Dorset Golden, and Anna apples; and Methley plums.
Do not bother trying to grow Elberta peaches or Red Delicious
apples. Both varieties require more cold weather than
we offer.
In terms of disease resistance it is most limiting on pears.
Bartlett pears inevitably are killed
by fire blight in our area, but Warren, Orient, Kieffer, and Ayers
do fine.
Some fruits require a pollinator. Of the species we are discussing in this article,
only apples require a pollinator.
Some plum varieties would also require a pollinator, but Methley
seems to do fine with the native plums in the area.
Use Anna and Dorset Golden together for a good match.
Soil conditions are very important for successful fruit
production. Here in San Antonio we have two soil conditions
that limit fruit production, poor soil drainage and high pH (also
called alkalinity). It only
takes one year of wet weather for a peach or apple tree planted in
our heavy clay soil to develop a root rot and die. The best way to
overcome that problem is to plant your trees in a raised bed made
of used railroad ties and filled with commercial landscape soil.
Add two cups of slow release lawn fertilizer to the raised
bed and dig a hole in the middle for the tree. Dig the hole only as deep as the container and
three times as wide. Soak the
tree well at planting. Let
the hose run at a moderate velocity until the hole fills up with water. The soaking will help the soil to fill in around
the roots. Apples, peaches,
pears, and plums are not xeriscape plants.
Water them every time the soil dries to one inch. Drip irrigation or a soaker hose works best.
Soil alkalinity causes iron chlorosis. It can be so severe in our caliche soil that
fruit trees will turn completely yellow (chlorotic), and not be able
to support any fruit and few leaves.
The problem can be addressed by applying iron in a chelated
form supplemented by foliar iron sprays.
Chelated iron is a source of the nutrient that is attached
to a molecule that prevents the iron from being locked up in the soil,
but does not prevent it from being picked up by the tree.
You can purchase chelated iron as Ferrous Plus, Sequesterene,
and other products or you can make your own. Mix one cup of iron sulphate (copperas) with
one bushel of compost to form a good chelated material. Apply the enriched compost to the soil over
the fruit tree’s roots.
Another way to add iron is to spray it on the tree as a
foliar spray. Dissolve a chelated
iron product or copperas in a bucket and then apply it with a hose
and sprayer. Copperas is not very soluble, but it works even
if most of the product does not dissolve in the water. For a foliar spray to work, however, the tree
can not be in such a severe state that the leaves are small and deformed.
When you ask gardeners what happened to their peaches, quite
often they report borers killed them because they see the gummy sap
emanating from the trunk and branches.
The gummosis is usually the symptom of bacterial canker, a
disease caused by stress. Poor
drainage, excessive heat, drought, chlorosis, insects, and other stresses
are eventually expressed as bacterial canker.
The disease is the actual killer of the tree.
