Group Title: Bulletin - University of Florida. Agricultural Experiment Station ; 182
Title: Stem injury of tobacco caused by fungi growing on the poison mixture used for controlling bud worms
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Permanent Link: http://ufdc.ufl.edu/UF00026386/00001
 Material Information
Title: Stem injury of tobacco caused by fungi growing on the poison mixture used for controlling bud worms
Series Title: Bulletin University of Florida. Agricultural Experiment Station
Physical Description: p. 277-286 : ill. ; 23 cm.
Language: English
Creator: Tisdale, W. B ( William Burleigh ), 1890-
Kelley, J. G ( John Grady )
Publisher: University of Florida Agricultural Experiment Station
Place of Publication: Gainesville Fla
Publication Date: 1926
 Subjects
Subject: Tobacco -- Diseases and pests -- Florida   ( lcsh )
Fungal diseases of plants -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: by W.B. Tisdale and J.G. Kelley.
General Note: Cover title.
General Note: "Contribution no. 3 from the Tobacco Experiment Station, Quincy"-- T.p.
 Record Information
Bibliographic ID: UF00026386
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: aleph - 000923484
oclc - 18172683
notis - AEN4035
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HISTORIC NOTE


The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
(EDIS)

site maintained by the Florida
Cooperative Extension Service.






Copyright 2005, Board of Trustees, University
of Florida







UNIVERSITY OF FLORIDA
Agricultural Experiment Station



STEM INJURY OF TOBACCO

Caused by

Fungi Growing on the Poison Mixture
Used for Controlling Budworms

By W. B. TISDALE AND J. G. KELLEY




















Fig. 126.-Lower portion of stem of Connecti-
cut Round Tip tobacco plant showing loca-
tion and nature of lesion resulting from
fungi growing on poison mixture accumu-
lated around the stem.

(Contribution No. 3 from the Tobacco Experiment Station,
Quincy)

Bulletins will be sent free upon application to the Experiment Station,
GAINESVILLE, FLORIDA


May, 1926


Bulletin 182







BOARD OF CONTROL

P. K. YONGE, Chairman, Pensacola
E. L. WARTMANN, Citra
E. W. LANE, Jacksonville
A. H. BLENDING, Leesburg
W. B. DAVIS, Perry
J. T. DIAMOND, Secretary, Tallahassee
J. G. KELLUM, Auditor, Tallahassee

STATION STAFF

WILMON NEWELL, D. Sc., Director
JOHN M. SCOTT. B. S., Vice Director and Animal Industrialist
SAM T. FLEMING, A. B., Assistant to Director
J. R. WATSON, A. M. Entomologist
ARCHIE N. TISSOT, M. S., Assistant Entomologist
H. E. BRATLEY, M. S. A., Asst. in Entomology
R. W. RUPRECHT, Ph. D., Chemist
R. M. BARNETTE, Ph. D., Assistant Chemist
C. E. BELL, M. S. Assistant Chemist
E. W. COWAN, A. M., Assistant Chemist
J. M. COLEMAN, B. S., Assistant Chemist
0. F. BURGER, D Sc., Plant Pathologist
G. F. WEBER, Ph. D., Associate Plant Pathologist
J. L. SEAL, M. S., Assistant Plant Pathologist
ROBERT E. NOLEN, M. S. A., Lab. Asst. in Plant Pathology
K. W. LOUCKS, A. B., Lab. Asst. in Plant Pathology
ERDMAN WEST, B. S., Lab. Asst. in Plant Pathology
D. G. A. KELBERT, Field Asst. in Plant Pathology
W. E. STOKES, M. S., Grass and Forage Crops Specialist
W. A. LEUKEL, Ph. D., Assistant Grass and Forage Crops Specialist
A. F. CAMP, Ph. D., Plant Physiologist, Cotton Investigations
W. A. CARVER, Ph. D., Assistant Cotton Specialist
EDGAR F. GROSSMAN, M. A., Assistant Entomologist, Cotton Investigations
RAYMOND CROWN, Field Asst., Cotton Investigations
A. L. SHEALY, D. V. M., Veterinarian
D. A. SANDERS, D. V. M., Assistant Veterinarian
C. V. NOBLE, Ph. D., Agricultural Economist
BRUCE McKINLEY, B. S. A., Assistant in Agricultural Economics
H. G. HAMILTON, M. S., Assistant Agricultural Economist
OUIDA DAVIS ABBOTT, Ph. D., Head, Home Economics Research
GEORGIA WESTOVER, Assistant in Home Economics
HAROLD MOWRY, Assistant Horticulturist
G. H. BLACKMON, B. S. A., Pecan Culturist
IDA KEELING CRESAP, Librarian
J. FRANCIS COOPER, B. S. A., Editor
RUBY NEWHALL, Secretary
HENRY ZEIGLER, Farm Foreman
W. B. TISDALE, Ph. D., Plant Pathologist, in charge Tobacco Experiment
Station (Quincy)
J. G. KELLEY, B. S. A., Lab. Asst. in Plant Pathology (Quincy)
JESSE REEVES, Foreman Tobacco Experiment Station (Quincy)
L. O. GRATZ, Ph. D., Assistant Plant Pathologist (Hastings)
A. S. RHOADS, Ph. D., Assistant Plant Pathologist (Cocoa)
A. N. BROOKS, Ph. D., Assistant Plant Pathologist (Plant City)
STACY O. HAWKINS, Field Asst. in Plant Pathology (Miami)
J. H. JEFFERIES, Superintendent Citrus Experiment Station (Lake Alfred)
W. A. KUNTZ, A. M., Assistant Plant Pathologist (Lake Alfred)
GEO. E. TEDDER, Foreman, Everglades Experiment Station (Belle Glade)


K. H. GRAHAM, Auditor
RACHEL MCQUARRIE, Assistant Auditor








STEM INJURY OF TOBACCO
Caused by
Fungi Growing on the Poison Mixture
Used for Controlling Budworms
By W. B. TISDALE AND J. G. KELLEY

Each year since the inception of tobacco investigations in the
Florida-Georgia district in 1922 an occasional tobacco plant has
been observed with dwarfed, chlorotic and flecked lower leaves
accompanied by a brown to black lesion on the basal portion of
the stem. Examination of the few affected plants each year
failed to reveal the cause of the trouble. All attempts to associ-
ate a parasitic organism with the diseased parts were in vain.
Altho several fungi (Fusaria in most cases) and bacteria were
isolated from diseased stems, none of them produced any symp-
toms of disease when inoculated into the stems of healthy plants.
In May 1925, about 10 days after a light rain, the disease be-
gan to appear in epidemic form in several fields of both cigar
wrapper and bright leaf tobacco. Counts made in one 15-acre
field of cigar wrapper tobacco when the plants averaged about
three feet high showed that 38 percent of the plants had affected
leaves and 8 percent of the plants were dead. The most severe
infection found in fields of bright leaf tobacco was 18 percent of
the plants with leaf injury and about 4 percent dead.
All plants showing leaf injury at this time were found to have
the characteristic lesion on the stem at the surface of the soil.
Lesions were also found on the stems of several plants examined
which were not stunted nor bore any affected leaves. However,
no attempt was made to determine the percentage of plants hav-
ing stem injury without also showing leaf injury, as the trouble
was not considered of great importance except in cases suffi-
ciently severe to result in leaf injury.
In 1926 the disease was again observed in several fields of
wrapper tobacco. Signs of the disease this year, as in 1925,
became apparent in a week to ten days after a light rain which
fell after a period of four weeks of dry weather. In these fields
only an occasional plant died and a relatively small percentage
of the plants showed any leaf injury. However, a high percent-
age of the plants were stunted which appeared to be a result of
the stem injury. All stunted plants examined showed typical





Florida Agricultural Experiment Station


lesions on the stems, altho the injury did not extend thru the
cortex except on the plants which also showed leaf injury.

SIGNS OF THE
INJURY

Signs of the
injury which first
attract one's at-
tention are mot-
tled, chlorotic or
flecked lower
leaves (Fig. 127)
accompanied by
stunting of the
entire plant. Ex-
amination of the
stems of such
plants reveals a
dark brown to
black lesion lo-
cated at the sur-
face of the soil
and varying in
length from one-
half to more than
an inch (Fig.
126). The lesion
may be narrow
o r completely
girdle the stem.
I n the former
case only the
leaves immediate-
ly above the le-
sion are affected,
while in the lat-
Fig. 127.-Lower leaf of bright tobacco plant show- ter case all of the
ing nature of injury resulting from stem gird- lower e a v e s
ling caused by fungi growing on the poison mix-
ture accumulating around the base of the stem. may be affected
(Fig. 128), and if the injury extends thru the cortex, the plant
usually dies. Distinct lines of demarcation separate the healthy






Bulletin 182, Stem Injury of Tobacco


from diseased tissue. In advanced stages the affected tissue
dries and shrinks, giving the lesions a sunken appearance (Fig.
129). Upon drying out the dead tissue frequently cracks
lengthwise, especially in cases where the injury is limited to
one side of the stem. Brown streaks are usually apparent in
the cambium and the inner cortex between the stem lesion and
the affected leaves.

CAUSE OF THE INJURY
Field examinations revealed that all affected plants had a lump
or crust of the corn meal-arsenate of lead mixture used for con-
trolling the budworm at the base of the stem and in contact
with the in-
Fig "d jured parts.
.~ These lumps
S. or crusts of
Sthe poison mix-
ture were hard
and were over-
run by fungi.
At first it was
thought p os-
sible that the
arsenate o f
lead contained
in the mixture
might be re-
sponsible f o r
the injury and
experiments
Fig. 128.-Badly stunted and dwarfed bright tobacco e r e co n-
plant caused by fungi growing on the poison mix- ducted to de-
ture around the base of the stem. termine t h is
hypothesis.
A saucer-shaped excavation one-half inch deep was made
around vigorous young tobacco plants growing in the field and
a level tablespoonful of the poison mixture or pure corn meal
was placed in the hole in contact with the stems. Other plants
were treated in a similar manner with an equal amount of the
poison mixture to which hydrated lime had been added at the
rate of two pounds of lime to 75 pounds of the poison mixture.






Florida Agricultural Experiment Station


The lime was added to counteract any free arsenic which might
be present in the mixture. The materials were moistened
slightly after they were placed around the plants.
One week after the treatment the lower leaves of some of the
plants of each of the three lots were chlorotic and had brown
specks distributed over the surface. Three days later the leaf
margins had dried out and the plants showed retarded growth
as compared
'S with the checks.
SThe stems of all
treated plants
showed injury
S ( similar to that
found occurring
in the fields.
These experi-
ments seem to be
sufficient proof
that the arsenate
of lead is not the
cause of the in-
jury.
After it was
ascertained that
Srf t. the same type of
Injury was pro-
S duced with pure
Scorn meal as with
/ the corn meal-ar-
senate of lead
mixture, atten-
tion was directed
Fig. 129.-Stem of bright tobacco similar to that
shown in figure 128, showing sunken condition to the organisms
of stem lesion and depth of injury, found growing
on the mixture. Lumps of the poison mixture were brought
into the laboratory and placed in moist chambers at room tem-
perature. After a few days several different organisms had
begun to sporulate on the surface of the material, each one ap-
parently dominating in certain areas. Spores of each form
were transferred to slants of potato-dextrose agar and to plates
of sterilized corn meal. In most cases pure cultures of the or-





Bulletin 182, Stem Injury of Tobacco


ganisms were obtained at the first attempt, while others re-
quired a second transfer to free them from bacteria. By this
method four fungi-Aspergillus ofyzae (Ahlb.) Cohn, Asper-
gillus niger van Tieg.,1 and one species each of Mucor and Peni-
cillium were obtained in pure culture. A Fusarium also devel-
oped on the lumps of poison mixture in the moist chambers but
very little growth appeared on the surface of the pabulum so it
could not be readily freed from the bacteria. No inoculations
were made with the Fusarium.

RELATION OF THE FUNGI TO DEVELOPMENT
OF THE STEM INJURY

After the organisms had covered the surface of the corn meal






















Fig. 130.-Photograph of tobacco seedlings showing severe injury resulting
(right) in contact with the stems. Plant on the left was treated with
sterilized uninoculated corn meal for check. Photographed Jan. 6, 1926,
one week after inoculation.
contained in the petri dishes, which was about four days, the
contents of each dish were cut into four pieces and each piece

'The author is indebted to Prof. E. M. Gilbert of the University of Wis-
consin for his assistance in identifying the organisms.






Florida Agricultural Experiment Station


then broken into smaller pieces and placed in contact with the
stem of a vigorous young tobacco plant growing in sterilized
soil in the greenhouse. The inoculated material was placed
just below the surface of the ground and a little soil placed over
it. Other plants were treated with an equal amount of steril-
ized uninoculated corn meal.
One week after the material was applied two plants of each
lot were removed for examination. The comparative condition
of the plants at the end of that period is shown in Figures 130
and 131. As may be seen, the plants treated with cultures of













IA
r A






Fig. 131.-Photograph of tobacco seedlings showing slight injury produced
by placing corn meal cultures of Mucor sp. (center) and Penicillium
(right) in contact with the stems. Plant on the left was treated with
sterilized uninoculated corn meal for check. Photographed Jan. 6, 1926,
one week after inoculation.

A. oryzae and A. niger were completely girdled. The injury ex-
tended thru the cortex and into the vascular tissue and the leaves
had begun to wilt. The stems of plants treated with cultures
of the Mucor and Penicillium showed very slight injury and the
controls showed no injury whatever. Other plants of the differ-
ent lots examined one week later showed practically no change
in degree of injury to the stems. However, at that time a Mucor






Bulletin 182, Stem Injury of Tobacco


had partially over-run the checks but no injury was apparent.
The injury produced by the species of Aspergillus in these ex-
periments was more severe than that observed in the fields
under natural conditions, but other experiments with older
plants indicate that it was due to the difference in age of the
plants.
In order to determine whether the organisms were parasitic
on tobacco plants, vigorous young plants were inoculated by in-
serting fragments of pure cultures of the fungi into the stems
at the surface of the soil. After one week the plants inoculated
with A. oryzae and A. niger showed slight discoloration of the
wounded tissues at the points of inoculation. The others showed
no difference from the checks. After two weeks the discolored
cells had sloughed off and all inoculated plants exhibited about
the same symptoms as the checks. The wounds had calloused
over and showed no signs of fungous invasion. Attempts to
re-isolate the fungi from the inoculated plants were unsuccess-
ful. However, the species of Aspergillus were isolated from a
few affected stems brought in from the fields.
Therefore, it appears that the injury is of indirect nature,
perhaps due to a byproduct of the fungi growing on the corn
meal.
DISCUSSION

Corn meal-arsenate of lead mixture (1 pound arsenate of
lead to 75 pounds of corn meal) has been used quite successfully
for the last decade in Florida for controlling the budworm on
shade-grown tobacco.' During that period there has been no re-
port of serious injury to the stems until 1925, thus indicating
that the injury is dependent upon a combination of certain
weather and cultural practices. In 1925 there was no rainfall
between April 4 and May 12, which was quite unusual for that
season of the year. On the latter date certain localities received
a good rain, while others received little or none. The fields which
received a light rain on May 12 suffered most severe injury from
the poison mixture, while irrigated fields and those which re-
ceived a heavy rain suffered little or no injury.
The poison mixture is applied to the buds of tobacco plants
twice a week from the time they become established in the fields

"A. C. Morgan and F. L. McDonough. The Tobacco Budworm and Its
Control in the Southern Tobacco Districts. U. S. D. A. Farmers' Bull. No.
819. 1917-revised 1923.






Florida Agricultural Experiment Station


until they have been topped. A small portion of the mixture is
dropped into the buds each time. Some of the mixture from each
application trickles down and accumulates on the ground around
the base of the stems. As the rapidly developing leaves expand
more of the mixture is shaken off which also falls to the ground.
During normal seasons rains are sufficiently frequent and heavy
to wash away the poison mixture from the leaves and from the
base of the stems. In 1925, however, eight or ten applications
of the mixture were made during the dry period, thus permit-
ting the accumulation of a considerable'quantity of the material
in the axils of the leaves and on the ground around the plants.
The light rain coming on May 12 was just sufficient to wash off
the surplus from the plants and leave it in a moist lump around
the base of the stems, making conditions favorable for the
growth of the fungi.

CONTROL

Since stem injury of tobacco resulting from the accumulation
of poison mixture around the stems has occurred only twice
during the number of years it has been in successful use for
controlling the budworm and since the injury occurred on these
occasions about one week after a light rain terminating a long
dry period, it seems that this type of injury will always be of
minor importance. If such weather conditions should again ob-
tain, it appears that the injury may be prevented by modifying
the method of applying the poison mixture and cultural prac-
tices. During dry periods tobacco in non-irrigated fields grows
slowly and one application of the poison per week may be suf-
ficient to keep the buds protected from the budworm. By this
practice there would be less of the material to accumulate around
the stems. If it were found to be impractical to reduce the num-
ber of applications of the poison mixture in order to keep the bud-
worm under control, the amount of the mixture should be re-
duced to a minimum at each application, and the soil could be
stirred around the plants with a hoe or more soil worked to the
plants with a plow. By this means the mixture could be re-
moved from contact with the stems or covered before it re-
sulted in injury to the plants.




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