PRESS BULLETIN No. 76.
florida Agricultural Experiment Station.
THE CINNAMON FUNGUS OF THE WHITEFLY.
BY H. S. FAWCETT. -
A fungus somewhat resembling the well-known Brown Fungus in
color, though of a more cinnamon brown, has been observed on white-
fly larvae at various times during thepast two or three years. It was
first brought to the writer's notice in the fall of 1905, by Dr. E. H.
Sellards (then Entomologist of the Florida Experiment Station), who
thought that it might prove to be the spore-bearing stage of the Brown
Fungus. The Brown Fungus, known in Florida since 1896, had never
been observed in a spore-bearing condition; but this cinnamon colored
fungus was found to be producing an abundance of spores.
At first sight one might mistake the Cinnamon Fungus for the
Brown Fungus. The color of the raised, hemispherical pustules, how-
ever, is a cinnamon brown, and they usually present a powdery ap-
pearance. Under the hand lens they are seen to be brush-like in form,
bristling with a mass of cinnamon colored hyphae. From the margin of
the cinnamon colored pustules there grows out a layer of white inter-
woven threads, which spread for a little way over the leaf. From these
white threads, as well as from the top of the pustule, there arise up-
right stalks, which bear the minute spores.
EXPERIMENTS WITH THE FUNGUS.
Experiments were begun in 1905, with the view of determining
whether this spore-bearing form belonged to the Brown Fungus, or was
another species. By transferring spores of the Cinnamon Fungus to
culture media in the laboratory, pure growths of the fungus were ob-
tained. Spores from these were transferred to whitefly larvae on orange
trees in the greenhouse, with the result that pustules, identical with
those from which the growth .was first started, were again obtained.
These pustules retained their cinnamon brown powdery appearance, and
December 14, 1907.
were not observed to change to the smooth, hard form, so characteristic
of the-Brown Fungus. During the past summer the Cinnamon Fungus
has been introduced at several places into whitefly infected trees, by the
leaf-pinning method commonly employed for the Red and Brown Fungi.
SCIENTIFIC NAME AND RELATIONSHIP.
The cinnamon colored fungus is a species known scientifically as
Verticillium heterocladum. As far as is known it has not been reported
before as occurring on whitefly larvae, or on scale insects, in this coun-
try. Verticillium heterocladum was first described by O. Penciz, about
1887, as occurring on a soft scale insect (Lecanium) on lemon leaves in
Italy. Several closely related species of Verticillium have been reported
in Europe as occurring on insects; one on plant lice, and at least two
others on small insect larvae. Recently a cinnamon colored fungus,
which appears to be identical with the one on whitefly, was found on a
scale insect (Diaspis), on the strawberry bush or spindle tree (Euonymus
americanus), in the woods near Gainesville.
FUNGI PARASITIC ON WHITEFLY.
The addition of the Cinnamon Fungus swells the list of fungi that
are known to be more or less parasitic on the whitefly, to six species.
They have been published as parasitic on the whitefly in the following
Red Aschersonia (Aschersonia aleyrodes) ............1893
The Brown Fungus, (Spores unknown) -------------1896
Yellow Aschersonia, (Aschersonia flavo-citrina) -- 1906
Red-Headed Fungus (Sphaerostilbe coccophila) .-----. 1907
White Fringe Fungus, (Microcera sp.) ------- 1907
Cinnamon Fungus (Verticillium heterocladum) ------- 1907
Of the above species, three-the Red and Yellow Aschersonia,
and the Brown Fungus, have been sufficiently tested to receive good
recommendations as whitefly parasites. The Red-Headed Fungus oc-
curs only occasionally on whitefly larvae. The White Fringe Fungus is
widely distributed throughout the state, but as it has only recently been
proved to be parasitic on the whitefly, we do not yet know how effi-
cient it will be. The Cinnamon Fungus has been known for a number
of years to do good work, but the fact that it is a species separate
from the Brown has only recently been shown.
State papers please copy.