The Palatka news and advertiser. [volume] (Palatka, Fla.) 1908-19??, 1915-01-22
THE CITRUS CANKER
STARTS IN TREES BARK
Declares Prof. Rolls of State
Experiment Station.

Not only in the foliage and fruit,
bit in the bark of the trees, is found
the citrus canker fungus, according
to a report made by P. u. Rolls, of
the Florida State agricultural expe-
riment station who credits Prof. Ste
vens with making this discovery,
which it is believed will have an i'm
portant bearing on the methods of
treatment for the disease. This dis
covery was found only by careful
work in the laboratory and by the
aid of the appliances found in such
places, saws Mr.. Rolls in a communi-
cation published in a Jacksonville
paper. He considers this find second
in Importance only to the discovery
of the ca1sative agent of the disease.
In regard to the search which end
ed in the finding of fungus in the
bark of the trees, Mr.. Rolf says:
"In connection with the work on
citrus canker let me cite fine piece
of work that Professor Stevens has
done since about the first of August,
and one that was reported at the
Citrus Seminar, but not appreciated
at that time for it's full value-and
even at this time is not appreciated
generally by those who are interested
in citrus canker. You will probably
remember that in the first treatment
for citrls canker the trees were cut
back to the large limbs and where a
tree was small it was cut back to just
above the bud. These large limbs
and trunks were then painted over
with carbolineum in some cases, and
in other cases with Bordeaux mix
ture. In spite of this drastic treat
ment canker appeared in what seem
ed to be a redoubled virulence on the
new shoots.
"This gave rise to the idea that
canker was a sap disease. How.
ever, by that time Professor Stevens
had proven that the disease was due
to a germ. 1t was necessary to dis
cover the cause for the recurrence
of canker on trees where it had ap'
.parently been eradicated Some
people advanced the idea that the
spores had been lodged on the groInc
and were then carried back to the
new shoots and leaves that were de
veloping. This would seem to bt
altogether probable from what we
knew technically about the fungus
However, it seemed that the phenom
ena observed was such as could no
be fully explained in this way.
Canker Found in the Bark.
professor Stevens, therefore, tool
up the study in a methodical man
ner to find if any portion of tret
might be effected without producing
visible LESSONS. After much pains
taking work and the exhausting O.
an almost tireless patience, thu
search was rewarded by finding tina
canker lodged in the bark of thu
tree. He first found it in the young
err bark that was only about a yea
old. Once having learned how to de
tect it he continued his research ant
found that bark even five years oil
was capable of being infected. H
found these infection spots produc
ing myriads of spores. The task
however, of finding the causativ
agent was an easy matter compares
with finding those hidden canker in
fections in the roughehed bark o
the citrus tree. They are not visi6l
to the unaided eye. Even whel
pointed ont after they have been dis
covered one sees nothing unusua!
Bv means of a hand lens a SINAI
break may be discovered, but moth
ing that looks suspicious, but whe
these small openings are under I
powerful microscope we find tn
spore, imbeded in tissue that appear
to the unaided eye to be perfect
healthy. The matter is further con,
plicated by the fact that when tn
citrus bark is dry the small rift
close up, covering the fungus with 1t
tissue, then when moisture is pres
ent, as during rains, the banks file
with water and the fungus spore
are allowed to protrude. An insec
crawling up the trunk of the tree an
running over these spore masses WI
carry them, since the spores are In
cllded in a mucilaginous mass. Bird
lighting on the branches can readil
get these spores on their feet. PEI
sons handling the trees, as durln
pruning time or when gatherln
fruit, if the trunk happens to b
moist, would get these spores on the
hands.
Importance of This Discovery.
"The above information in regar