Xtremehorticulture

Oranges Have Strong Winter Roots But Weak Tops in Cold Climates

Q. We have an orange tree in our backyard with only two fruit. I
noticed there are two different looking branches. One has bigger leaves with
flowers and the other one has smaller leaves and thorny branches but it is getting
bigger and fuller. Is my tree going to produce fruit or not?

Citrus died and sour orange rootstock took over



A. Citrus trees purchased from nurseries, like most other fruit
trees, are two trees combined into one. They are grafted together when they are
very young. One tree provides good quality roots but poor quality fruit. The
second tree provides the top of the tree which has good quality fruit.


            A common tree
grafted to citrus because of their strong roots in our cold climate is sour
orange. It is very tolerant of winter freezing temperatures. The fruit looks
beautiful but it is extremely sour; too sour to eat fresh.

Purple leaf plum with huge sucker coming from the rootstock (right)

            Sour orange is
grafted onto many wonderful citrus trees that provide high quality fruit. Most
are more sensitive to winter low temperatures while the sour orange roots are
not. If you look closely, you will see a crook or “dogleg” where the two trees are
joined together.

            Sour orange, when
it is young, may sprout suckers that grow from this “dogleg”. If they are not
removed but allowed to grow, they produce very vigorous stems that are very
thorny. They eventually dominate the top which produces good fruit and perhaps
even cause it to decline and die.

            Sometimes the
more winter tender top may die while the sour orange roots will sucker and
produce a vigorous tree with horrible but beautiful orange, fresh fruit. These
thorny citrus suckers eventually replace the more desirable citrus tree.

            The solution? Remove the sour orange
sucker where it grows from the trunk. Make sure your pruning saw or shears is
sharp and sanitized. Do not lay it on the ground after it has been sanitized where
there are soil diseases that can harm the tree. There is no need to paint the
wound but allow it to heal on its own.

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