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These
viruses are often chronic and don't necessarily kill
the tree outright. However, these old citrus can
still produce fruit and remain ornamental and
productive for some time with good supportive
management and planning.
One common debilitating virus found in old backyard
citrus is called tristeza. A classic symptom of
this disease is a notable abnormal swelling or
thickening of the wood just below the bud union.
There may also be small pinholes on the inside of
the bark. A general decline may also be noted.
While this virus is spread by some aphids, it is
best controlled by planting citrus grafted on
tristeza-tolerant or tristeza-resistant rootstocks
which most grafted garden center-purchased trees
will offer. Another virus often encountered in
dooryard citrus is called psorosis. Psorosis is a
complex of diseases that cause bark symptoms
including bark scaling, curling and sap or gum
bleeding. Transmission of this disease occurs only
via infected budwood. Again, new citrus trees are
clean of this problem thanks to careful sanitation
and certification programs. There are other minor
viruses that appear in old citrus from time to time
causing similar symptoms or mild leaf
discolorations. Decontamination of pruning tools
between cuts is always a good idea as a general
sanitation technique so that no viruses are
transmitted from tree to tree.
You can plan ahead for the eventual removal of old
trees by planting new citrus. The selection is very
good and only limited by what you like in citrus.
In the mean time, provide good management practices
to help support your old citrus trees. Using a
recommended "Citrus Special" fertilizer as per label
instructions, feed your old citrus about three times
per year. Hand-in-hand, provide proper irrigation
keeping in mind that citrus do not like "wet feet"
and do not need to be mulched. Scout for and
suppress insects such as aphids and scale insects by
using a least toxic product such as horticultural
oil; again as per label instructions. Common
diseases can often be controlled with copper
sprays. As usual, our office can help with
identifying pests and recommending common-sense
management options. Always read the label before
selecting or applying any pesticide.
Pruning old citrus trees should be left to a minimum
with only dead or crossing branches needing
removal. Otherwise, enjoy your citrus in its old
age. Once you have determined that it is no longer
usefully ornamental or productive, remove it as
newer citrus (previously planted nearby by you) take
their place and come to fruit-bearing age. As with
people, older citrus will show their age. However,
with supportive management, even chronically
affected citrus can still contribute to your
landscape and table. For more information on all
types of citrus topics, please
contact our
Master Gardeners on the Plant Lifeline at 764-4360
from 1 p.m. to
4 p.m. Mondays, Wednesdays and Fridays. Our office is located
at
25550 Harborview Road, Suite 3
in Port Charlotte. Our Plant Clinics are available
across the county:
Demonstration
Garden at 7000 Florida Street, Punta Gorda from
9 a.m. to
11 a.m every Thursday.
Englewood/Charlotte Public Library 9 a.m. to
noon every Monday.
Murdock Public Library the first Thursday of the
month from
1 pm to
3 pm.
Punta Gorda Crossing Publix the third Friday of the
month from 9 am to
Noon
Monthly Plant Clinics are Saturdays from
9 a.m. to noon at the following locations: Peachland Promenades Publix ‹ second Saturday of the month;
Burnt Store Publix ‹ third Saturday of the month
Home Depot fourth Saturday of the month
Ralph Mitchell is the county extension director/horticulture agent for the
Charlotte County Cooperative Extension Service. You
may contact him
by e-mail
Ralph.Mitchell@charlottefl.com
You may also contact a volunteer Master Gardener
from
1 p.m. to
4 p.m. Monday, Wednesday and Friday at 764-4340 or by e-mail
Master.Gardener@charlottefl.com
Resource: Ferguson, J. J. & Garnsey, S. M. (1993)
Citrus Viruses and Virus-Like Diseases, The
University of Florida Extension, IFAS. 
Ralph E. Mitchell is a Horticulturist
and Charlotte County Extension Agent
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