The Florida agriculturist. [volume] (DeLand, Fla.) 1878-1911, 1885-02-04
The Diseases of the Orange.

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An Essay by VIM. II. Ashmead, read before
the florida Fruit Growers Association,
Jacksonville, Fla, February, 1894
Mr.. President and Gentlemen:
Although the orange tree in Florida is
less free from disease than any other
fruit tree known to pomologists, yet
there are some diseases which have
lately been brought into prominence that
claim attention and study, and | shall
contlne my remarks to my investigation
OF such OF these as have been brought
under my immediate observation.
On looking into the subject, one is as
tonished to see how remarkably free
from disease the orange tree is.
When we take into consideration the
millions of trees now being cultivated,
the different methods used, and the nov
ices that are cultivating this fruit, it is
indeed wonderful, that so few trees are
attacked by diseases that so seldom
prove fatal.
In all soils and under the most I'M
favorable conditions the orange tree
lives; frequently stunted, diseased and
unfiourlshing but after years of neglect,
with proper care and attention, it sur
wives and fiourishes, and in short time
generously rewards the cultivator with
an abundance of fruit.
Manville, the latest writer on orange
culture, enumerates five diseases to
which the orange tree is liable:
Die-Back, Limb-Blight, Gum Disease
or Bleeding, Foot-Rot and Smut or Black
Rust r
Of these, only two need cause the or
ange grower any serious apprehensions,
Die-Back and Foot-Rot, to which have
given much time and study. The others,
in many instances, are due to improper
cultivation, or the result of causes that
may be eradicated and controlled by the
grower.
DIE-BAcK.
The die-back disease, as a serious
trouble in orange culture, first began to
attract the attention of the grower more
than dozen years ago. Mr.. J. H.
Gates, of Palatka, was the first to call
the attention of the United States Agri-
cultural Department to this particular
disease.
Under date of November 81, 1873, he
writes: 'Please find enclosed, three
branches OF an orange tree having rusty
appearance, and in sol,la cases biistered.
| have trees which have lost all their
tops apparently from the same cause.
Any information relative to the cause or
cure, will be gladly received by myself
and neighbors.
Mr.. W. f. White. of Tampa, wrote
under date of April 10, 1873, to the De-
partment as follows:
"We have the disease of the orange
tree known as 'Die-Back. 1t has lately
appeared at this place. We have no
underdrains; but it is equally as bad on
pine land, hammock or shell land. Some
of our trees are almost killed by this dis
ease, while in other cases only a few
limbs are injured. The trees once al
fected make very little growth after
wards
Mr.. G. B. Magruder, of City Point,
wrote under date OF May "a, 1874:
We are considerably uneasy about
kind of rust that seems to be spreading
in our orange groves, and seriously af-
fecting some OF the youngs trees. The
bark of the limbs becomes encrusted
with what appears to be the sap exuding
through the pores, and afterwards hard
ening. The tree takes on fresh growth
in the spring and then all the young
shoots turn white and die, the whole
tree becoming scrubbv, diseased, and
apparently dying out. We can imagine
no cause and have found no remedy.
You will confer great favor if you can
suggest one"
The Department failed to suggest
remedy or state the cause of the disease,
and up to the present time it has been
the subject of controversy.
A die-back-affected orange tree is
easily recognized. The first symptoms
are vigorous growth of shoots or sucker
sprouts; these are generally angular,
t1attened and twisted; foliage heavy aid
curled, of very dark green; blisters
and eXcrescences appear just beneath
the bark filled with gelatinous sub
stance or coagulated sap. The buds are
prematurely and abnormally developed
and present diseased appearance. In
the final stages OF the disease the blisters,
from an accumulation Of sap, burst the
tissue of the outer bark, and become
hardened and oXidized. The circulation
of the sap is thereby prevented and die
back, or dying back of the shoots, then
sets in.
IT'S CAUSE.
DIR. kenworthy and other investigators
claim the disease to be of fungoid origin,
but none have been able to detect the
fungus.
Upon careful microscopical examination
OF die twigs sent me from South
Florida, l discovered in May, 1882, in
the different layers beneath the bark,
botanically called the dlbumen or sap
wood, and in the cambium or mucilagi-
nous layer. in which the new wood and
bark are developed, the filaments of a
fungoid, which unquestionably settles it
to be of fungoid origin. In my opinion
this fungus acts as a Stimnlant on the