PRESS BULLETIN No. 83.
Florida Agrcaillural Experimeht Stalion.
FUNGUS PARASITES OF HARD OR ARMORED SCALES.
BY E. W. BERGER.
The fungus and other parasites of scales are remarkably effective when
they have once gained a foothold in scale-infested trees. It is becoming
more and more evident that if we should expend even a small fraction of
the time and energy necessary for successful spraying or fumigating, in in-
troducing and spreading the natural enemies of scales (especially the
fungi), the results would be equal to the most successful spraying, and
the cost would be much less. The fungus parasites of the hard, or armored,
scales are peculiarly effective in keeping these scales in check, and so will
be alone discussed here.
THE ARMORED SCALES.
These are the commonest of the scale insects, and are distinguished
from the Lecaniums (the soft, or naked, scales), the cottony-cushion scale
and others, by having, as a protection, a father firm waxy covering, alto-
gether distinct from the body-wall or skin. It is this extra covering (the
visible scale) which makes it so difficult to kill these scales by spraying.
The purple, long, and chaff scales of citrus, and the San Jose and white
scales of peaches, are good examples of the armored scales.
THE RED-HEADED SCALE FUNGUS.
This fungus is widely distributed in Florida and in'the Gulf States,
and has been reported from near Philadelphia, Pa. It is quite omnivorous
in its habits and will probably thrive on all the different species of armored
scales. It occurs in abundance on the obscure scale of oaks, and sometimes
on the scales of maples and of Chinaberry trees, while it is probably the
chief parasite on the scales of citrus trees and on the San Jose scale. Its
presence is a boon to the citrus grower. The writer has seen trees in which
many branches had the appearance of having been sprinkled with coarse
red brick-dust, the color being due to the abundance of this fungus. In such
trees the mortality of the scale must have been fully as great as could have
been obtained by the most effective spraying.
Its efficiency in reducing the ravages of the San Jose scale has been
known since 1897, when Prof. P. H. Rolfs reported (Bulletin 41, Fla. Agri-
cultural Experiment Station) the remarkable mortality of this scale at De-
Funiak, Fla., as being due to this fungus. During the summer of 1906, Mr.
F. P. Henderson of Gainesville, Fla., enthusiastic over his success in his
own peach orchard, prevailed upon the Griffing Brothers Co. and the Gaines-
ville Orchard Co. to allow him to introduce this fungus into their exten,
sive peach orchards (comprising 950 acres). Judged by reports and inspec-
March 4, 1908.
tions made by members of the Station staff, this undertaking was a marked
success. Since then Mr. Henderson has furnished fungus for hundreds of
THE WHITE OR GRAY-HEADED SCALE FUNGUS.
This fungus appears to be as widely distributed in Florida as the Red-
headed Fungus, and the writer has occasionally observed instances when it
was quite as abundant. In efficiency it is probably the equal of the Red-
headed Fungus, in so far as the scales of citrus trees are concerned. In
appearance the Gray-headed Fungus is quite like the Red-headed Fungus, ex-
cept for its color, which varies from nearly white to dark gray or brown-
THE BLACK FUNGUS.
Small black spots, slightly elevated, generally of various sizes, and some-
times more than one-eighth of an inch in diameter, are often found on the
limbs of scaly trees. These are fairly certain to be -the Black Fungus. It
is widely distributed throughout Florida, and may probably be found on
nearly all the common armored scales. When this fungus becomes abund-
ant on the fruit of citrus trees it is difficult to wash or brush it off by
HOW TO INTRODUCE THESE FUNGI.
One or other of these fungi is abundant upon citrus trees in nearly all
parts of the State. The Red-headed and Black Fungi are also frequently
abundant on peaches, oaks, maples, Clinaberry trees, and other trees in-
fested with armored scales. Large quantities of the Red-headed Fungus
have been collected from oaks. The White-headed Fungus has, up to the
present, been found only in citrus groves.
For use as infecting material, cuttings of branches or twigs, three to
six inches long, are generally made, or the fungus may be simply scraped
from the trees. To introduce these fungi into scale-infested trees, the best
method is to tie firmly one or several such cuttings (or- small pieces of
bark), to the upper side of the limbs. If abundant fungus is available, it
should be freely used. The infecting material should be tied high up in
the trees, and should be distributed (especially if it is scarce) in such a
way that many centers of infection are established.
Another method would be to tie a piece of cardboard against the
scaly part of a tree so as to form a "wall pockett" Some fungus mater-
ial scraped from scale-infested trees or from leaves is placed in this pocket,
and kept moist for a few days with a wad of wet cotton or sphagnum moss.
This method is reported as having given good results with the Red-headed
Fungus, but is probably also applicable to the other fungi.
The best time for introducing these fungi is during the period of sum-
mer rains. As they grow only on scale-insects, it would be futile to under-
take to introduce them into trees free from scales.
State papers please copy.