Citrus Tree Disorders - When Your Citrus Tree Problem Is Probably Not An Insect or
Disease
By Ralph E. Mitchell
This is a good time of year to discuss what is called disorders in citrus trees. Disorders
tend to be problems related to a combination of factors including general stress,
environmental issues, nutrition, and even variety characteristics. Accordingly, while
disorders may be easy to diagnose, their remedy may be difficult to put into effect. What
are some disorders common to citrus in our area?
Perhaps the most common disorder brought to our attention by area gardeners is what is
called premature fruit drying or "granulation". When you open the fruit, the fruit is dry
and juice-less. This is a difficult disorder to get your hands on. It is sometimes common
in navel, mandarins, mandarin hybrids, grapefruit and Valencia, especially when they are
not harvested in time. Granulation can vary from season to season and may be more of a
problem with large fruit or a tree that blooms late. Weather may also be a factor as long
periods of warm and dry fall weather may predispose this condition. Young trees that
show this disorder will often grow out of it in time.
Another common disorder is fruit splitting. Fruit splitting is associated with high
temperatures, humidity and rainfall from August through mid-December. Water taken up
after a long period of dryness helps burst the peel open along the bottom of the fruit.
This disorder is also associated with deficiencies in potassium.
Some dead wood in citrus trees is normal and expected. However, excessive twig
dieback is a disorder associated with a combination of problems that are very variable.
Consider that freezes, drought, pests, viruses, flooding, and pesticide burn that may have
caused leaf drop and associated root damage can result in dead twigs.
Fruit drop is another common disorder. Severe fruit drop can occur when hot, rainy
weather occurs in the fall. Anything that injures a fruit will trigger the production of
ethylene gas which will cause fruit drop to occur. Again, nutrient deficiencies such as
low potassium can compound the problem.
Believe it or not, citrus can sometimes get sunburned! Thin-skinned citrus such as
Murcott tangerines are known to get burned by long periods of direct sunlight. Besides
skin drying, the fruit below will also be affected.
So, before you blame an insect or disease for a citrus problem, check out the possibility
of a disorder. While proper fertility, good drainage and high ground will help alleviate
these problems, keep in mind that some things such as weather and individual variety
characteristics are beyond your control. For more information on all types of citrus
topics, please contact our Master Gardeners on the Plant Lifeline at 764-4340 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 every Thursday from 9 to 11 a.m.
Englewood/Charlotte Public Library 9 a.m. to noon every Monday.
Mid County Regional Library first Thursday of the month from 1 to 3 p.m.
Monthly Plant Clinics are Saturdays from 9 a.m. to noon at the following
locations: Cape Haze Publix first Saturday of the month;
Peachland Promenades Publix ‹ second Saturday of the month;
Home Depot Murdock and Home Depot Punta Gorda the third 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:
Zekri, M. and Rouse, R. E. (2002) Citrus Problems In The Home Landscape. The
University of Florida Extension Service, IFAS.