^50
FLORIDA STATE HORTICULTURAL SOCIETY, 1958
THE USE OF COBALT-60 GAMMA RADIATION IN
ORNAMENTAL HORTICULTURE*
Howard J. Teas
Florida Agricultural Experiment Station
Gainesville
The Florida Agricultural Experiment Sta
tion Cobalt-60 Irradiation Facility is an in
stallation for treating different materials with
radiation. It consists of a fenced area of about
five acres within which is an operating house
and a circular 6' high fence 200' in diameter.
See Figures 1 and 2. In the center of the
fenced enclosure is a 30' diameter radiation
pit, within which materials are placed for
irradiation. The source of radiation, a stain
less steel irradiator, contains the radioactive
cobalt. It is stored in a 13' deep tank of water
in the center of the radiation pit. In order
to carry out treatments, experimental materials
are positioned within the radiation pit, workers
leave the central fenced area, lock the gate,
and raise the irradiator from its underwater
storage place by cables. This is accomplished
by the use of a remotely operated motor
which is controlled from the operating house.
If a rate meter chamber is placed beside ex
perimental material the radiation dose rate
can be read on an instrument panel in the
operating house. When the radiation treatment
has been completed the irradiator is again
lowered into the water storage tank and work
ers reenter the radiation pit through the maze
driveway. Treated material can be handled
immediately, since cobalt-60 gamma radiation
induces no radioactivity in samples. An illus
trated description of the facility has been
published (13).
The radiation from the artificial radioiso-
tope cobalt-60 is electromagnetic radiation
that has the same characteristics as slightly
over 1 million volt X-rays. Cobalt-60 is pro
duced by neutron bombardment of ordinary,
non-radioactive cobalt-59 in an atomic re
actor; The radioisotope has a half-life of 5.3
years, that is, the amount of radiation which
is emitted in a given time from a piece of co
balt-60 will have decreased to one half in 5.3
years. The irradiator contains 6400 curies of
cobalt-60, which is equivalent radiation-wise
* This work was aided by Atomic
contract number AT-(40-l)-2402.
Energy
Commission
to more than 11 pounds of radium. The fa
cility and its operation is licensed by the U.S.
Atomic Energy Commission.
Such a facility
involves levels of radiation dangerous to per
sonnel, so that rigid safety precautions are
enforced.
The irradiation facility is intended for three
general types of plant investigations: A. Pre
servation of agricultural products by pasteuri
zation or sterilization treatments to kill or sup
press microorganisms or larger pests such as
insects or worms.
B.
Production o£ genetic
and cytological changes, which covers induc
tion of gene mutations and chromosomal
changes. C. Production of physiological effects,
which includes suppression of germination or
sprouting, stimulation or inhibition of growth
and the prevention of abscission.
Use of the Facility in Ornamental
Horticulture
Types of treatments. Uses of gamma radia
tion in Ornamental Horticulture include all
three general types of treatments.
A. The use of gamma radiation for pas
teurization, sterilization or deinfestation in
clude the possibility of radiation use in budwood sterilization treatment of cut flowers to
inhibit Botrytis developments and killing of
nematodes or insects. These applications have
not been developed, and thus their use in
any plant must be determined experimentally.
The feasibility of such treatments will be
determined by the relative radiation sensitivity
of the parasite or microorganism and the plant
itself.
B.
The use of radiation in the production
of inherited changes is probably the most
important. Genetic changes are these which
behave as though the hereditary units have
been altered. Cytological changes are those
which involve alterations at the chromosomal
level. Some apparent gene changes or muta
tions have been found to be caused by chromo
somal changes. In a search for economic mu
tants the distinction may be unnecessary. In
as much as the behavior of genetic and cy
tological changes is usually similar, they will
be treated together. For detailed considera
tion of the differences and significance see re-
452
FLORIDA STATE HORTICULTURAL SOCIETY, 1958
Earth
Concrete
Fill
Lid
9100r
Irradiator
162Or
69,6r
3100r
Radiation dose in r per hour
Fig. 2.
Radiation levels within the radiation pit.
as the use of radiation on bulbs to induce
earlier flowering in gladiolus (7), irradiation
of potatoes (10) and onions (1) to inhibit
sprouting and the associated deterioration dur
ing storage, and the treatment of snapdragon
flowers to inhibit geotropic bending (14).
Radiation levels required. Sensitivity to ra
diation is known to differ according to age
of tissue, between varieties and even as a
function of single gene differences. In radia
tion studies with any plant material it is neces
sary to establish tolerance levels and optional
growth for treatment. Sparrow and Gunckel
(11) have studied radiation tolerance in 79
species of plants. They reported that a dose
of 30 r per day damaged the trumpet lily,
whereas 6000 r per day was required for dam
age to gladiolus. Gustafsson (3) reported that
comparable doses for dormant seeds ranged
from 5000 r for sunflower to 90,000 r for white
mustard. Osborne (cf. 6) reports useful doses
of 2500 to 7500 r for fruit tree scions in mu
tant production, and 1000 r to 1600 r for sev
eral types of pollen.
The Florida Agricultural Experiment Sta
tion cobalt-60 irradiation facility at Gaines
ville is suitable for all these types of orna
mental plant treatment and several projects
are underway.
LITERATURE
CITED
1. Dallyn, S .L, Sawyer, R. L, and Sparrow, A. H.
Extending onion storage life by gamma irradiation. Nu
cleonics 13: 48-49. 1955.
2.
Edwardson, J. R. The effects of radiation on chromo
somes. Proc Fla. Soil and Crop Sci. Soc. 17: 119-129. 1957.
3. Gustafsson, A. The X-ray resistance of dormant seeds
in some agricultural plants. Herditas 30: 165-178. 1944.
4. Horner, E. S. The utilization of artificially induced
mutations in plant breeding programs. Proc. Fla. Soil and
Crop Sci. Soc. 17: 130-136. 1957.
5. Konzak, C. F. Genetic effects of radiation
plants. Quart. Rev. Biol. 32: 27-45. 1957.
on higher
6. Osborne, T. S. Mutation production by ionizing ra
diation. Proc. Fla. Soil and Crop Sci. Soc. 17: 91-107. 1957.
7. Sax, K. The effect of ionizing radiation
growth. Amer. Jour. Bot. 42: 360-364. 1955.
on
plant
8.
Singleton, W. R. The use of radiation in plant breed
pp. 183-194.
9.
Smith,
ing, in
Atomic Energy and Agriculture",
A.A.A.S. Wash., D. C, 450 pp. 1957.
mutations.
H.
Bot.
H.
Rev.
Radiation
24:
1-24.
in
the
1958.
production
of
useful
10.
Sparrow, A. H. and Christensen, E. Improved stor
age quality of potato tubers after exposure to cobalt-60
gammas. Nucleonics 12: 16-17. 1954.
11. Sparrow, A. H. and Gunckel, J. E. The effects on
plants of chronic exposure to gamma radiation from radiocobalt. Proc. Int. Conf. Peaceful Uses Atomic Energy 12:
52-59. 1956.
12. Teas, H. J. The effects of radiation on genes. Proc.
Fla. Soil and Crop Sci. Soc. 17: 108-118. 1957.
13.
Teas, H. J. Station installs cobalt irradiator. Sun
shine State Agr. Res. Report 3: 4-5. 1958.
14. Teas, H. J. and Sheehan, T. J. Unpublished results.
1958.
TEAS:
Fig.
1.
COBALT-60 GAMMA RADIATION
451
Aerial view of facility
views of Osborne (6), Teas (12) and Edwardson (2).
In most plants that have been studied mu
tations appear occasionally, usually quite rare
ly, from natural causes. Radiation has been
found to increase markedly the rate of ap
pearance of mutations. Most mutants are con
sidered as undesirable, that is, are inferior to
the normal or parental type. In certain crop
plants, for instance, only one mutant in 800
has proven superior agronomically (cf. 9).
Among ornamental plants, where novelty per
se is often desirable, the percentage yield of
useful mutations would be expected to be
higher than in crop plants. For operational
purposes mutation production in ornamental
plants can be considered according to how
the material is to be propagated, (a) In
asexually propagated plants, such as leafy
ornamentals, some shrubs, vines, etc., the en
tire plant or growing tip is irradiated and the
plant subsequently examined for mutant
branches or shoots, the so-called "bud sports".
Propagation of the selected mutant portions
is carried out by cuttings, budwood, etc. (b)
In sexually propagated plants, where repro
duction is by seeds, the seed, entire plant,
growing point, flower or pollen can be irra
diated. Most mutations are recessive, so that
more than one generation is required before
mutants can be detected. In the case of polyploids-, or self-sterile plants the recovery of
mutations is more difficult.
Among types of mutations that may be
sought are: Disease resistance, for instance
for fleck in the Easter Lily, blackspot in the
rose, Ascochyta rayblight in chrysanthemums,
and Fusarium rot in gladiolus. Radiation has
been used to obtain mutations for disease re
sistance in crops plants such as wheat, flax,
peanut, and oats (cf. 5). It is reasonable to
expect that irradiation of ornamental plants,
combined with an extensive mutant screening
program will yield comparable genetic resist
ance to diseases. Other types of mutations that
would be desirable include Nematode resist
ance, flower shape and color, leaf shape, flower
or leaf variegation, hardiness to cold, high
temperature or drouth, gigas or dwarf forms,
self-fertility, and many others.
C. Production of physiological effects. Phy
siological effects are those effects on the plant
not due to mutation or killing of micro or
other organisms. They include such effects
453
FLORIDA STATE HORTICULTURAL SOCIETY
NECROLOGY
he was called back to the Plant Board on
loan and played an important role in eradi
cating this pest.
Returning to the Experiment Station, he was
promoted to associate horticulturist in 1930,
horticulturist in 1932 and assistant director
in 1933. On November 1, 1943, he was made
director of this station, a post he held until
his retirement January 31, 1950.
He earned B.S.A. and M.S.A. degrees from
the University of Florida in 1929 and 1934 and
was awarded the honorary doctor of science
degree in 1950.
Dr. Harold Mowry and trophy presented by Cost- Ric
workers to Florida workers who had helped Costa Rica
search Jan. 5, 1957
Harold Mowry
Dr. Harold Mowry, 64, former director of
the University of Florida Agricultural Experi
ment Station and more recently consulting
director to the Minister of Agriculture and
chief of the University's cooperative mission
to Costa Rica, died November 12, 1958, at
University of Florida Teaching Hospital. He
suffered a heart attack as he completed seven
years of advisory work in Costa Rica in Jan
uary of this year and was hospitalized in
Washington for a while before returning to
Gainesville in March.
A native of Valley Falls, Kansas, he came
to Florida in 1916. For six years he was a
member of the State Plant Board inspection
force eradicating citrus canker from the state.
In 1922 he joined the staff of the Agricultural
Experiment Station and for a number of years
took the lead in developing horticultural re
search.
When the first infestation of the Mediterran
ean fruit fly was discovered in Florida in 1929
In 1951 he went to San Jose, Costa Rica,
as consulting director to the country's Min
ister of Agriculture under an appointment
from the U. S. Department of Agriculture.
When the University of Florida signed its
agreement with Costa Rica in 1954 through
the Servicio Tecnico Interamericano de Co
operation Agricola, he became chief of mis
sion and directed .the work of University
personnel assigned to Costa Rica for duty,
in addition to being consulting director.
While in Costa Rica he aided the agricul
ture of the little country materially through
demonstrating the value of minor elements in
the nutrition of the coffee plant. This work
enabled growers to increase coffee yields and
returns. On his departure from the Central
American republic, Costa Rica awarded him
a medal de merito and scroll in appreciation
of his services.
While doing research with the Florida
Agricultural Experiment Station he made the
initial findings showing the value of zinc as
a minor nutrient element on many mineral
soils of this state. As a result of this and suc
ceeding research, zinc is now widely used in
fertilizing horticultural and field crops.
Mowry
also
demonstrated
that
nitrogen
from the air is fixed by the roots of one spe
cies of Australian pine tree, similar to nitrogen
fixing by leguminous plants such as clovers.
His early research with tung oil trees gave
impetus to the development of this industry
in Florida and the South.
He was author or co-author of 13 bulletins
published by the Agricultural Experiment Sta
tion and numerous articles for scientific and
popular journals, as well as the Houghton
Mifflin Garden Dictionary.
454
FLORIDA STATE HORTICULTURAL SOCIETY
In 1947 he received the distinguished ser
vice award of the Florida Vegetable Com
"men who have done meritorious original
work in science, literature or the fine arts."
mittee.
Commencing early in life, he realized the
need for periodic rest from the turmoil of his
many activities and obtained it in Florida.
Gradually, his interests changed to horticul
ture as practiced in Florida and, in 1921, he
organized and became President of the Florida
Fruit Company, successor to Lake Bryant
Fruit Growers Association, which was formed
As a result of his outstanding research and
other service to agriculture, he was named a
fellow of the American Association for the
Advancement of Science and honorary life
member of the Florida Academy of Science.
In recognition of the especially meritorious
service rendered to the advancement of horti
culture in Florida and to the Florida State
Horticultural Society, the Society elected him
an Honorary Member in October 1950. He
held membership also in the Botany Society of
America, American Society for Horticultural
Science, Florida Entomological Society, Soil
and Crop Science Society, and Florida State
Florists Association.
Clarence Gerald Bouis
In 1869 Mr. Bouis was born on a farm in
Howard County, Maryland and educated in
the public schools of Baltimore and Washing
ton, D. C. After entering the business world
at the early age of fourteen, he completed
his formal education at the Maryland Insti
tute (now Baltimore Polytechnic Institute)
night school, graduating summa cum laude,
winning the first prize in gold donated by
George Peabody.
On December 15, 1890, he was married
to the former Hattie Elizabeth Moore, of
Washington, D. C, who died in 1944. They
had two daughters and four sons.
Late in the last century he reorganized the
Monumental Label Company of" Baltimore,
Maryland and for many years was General
Manager of its successor, the Maryland Color
Printing Company.
Many honors and appointments came to
Mr. Bouis during this phase of his active
business life. He was Chairman of the Presi
dent's Committee on Standardization of Pa
per Sizes and Quality, used in government
service; Consultant to the U. S. Coast & Geo
detic Survey and Chairman of the Joint Cost
Committee of the Label and Folding Box
Manufacturers National Association. In 1922,
Mr. Bouis was honored by Testimonial by
the Box and Label Manufacturers Association
for his faithful and effective work. In 1924,
he was elected to the Cosmos Club of Wash
ington, D, C.? whose members qualified as
in 1889.
He became a member of the Florida State
Horticultural Society in 1921 and in the late
20's and early 30's, was an active participant
at the Society's meetings and a life member.
As a Cooperator of the U. S. Bureau of Plant
Industry and in recognition of his activities
connected with Florida citriculture, he was
invited to attend the first International Soil
Science Meeting held in 1927. Beginning in
1921, he became interested in the Cleopatra
Tangerine as a commercial citrus rootstock,
and his early propagation and dissemination
of Cleopatra seedling and commercial citrus
budded on them did much to bring about the
present popularity of Cleopatra rootstock.
He was in the midst of his activities, work
ing with unflagging interest and devotion,
when he died at Leesburg, February 13, 1958.
Edward B. O'Kelley
Edward B. O'Kelley passed away in Jack
sonville, Florida, on February 1, 1958, at the
age of 69. He was born in Hall County, Geor
gia, and received his Bachelor of Science De
gree in Agriculture from the University of
Georgia in June, 1914, and married Miss
Bessie Blackwell the same year.
At the time of his death Mr. O'Kelley was
retired General Agricultural and Livestock
Agent for the Atlantic Coast Line for Georgia,
Florida, and Alabama.
Mr. O'Kelley was past President of the
Railway Development Association for the
Southeast, a member and past president of
Murray Hill Civic Club, Florida State Cham
ber of Commerce, and a member of the Flo
rida State Horticultural Society.
Mr. O'Kelley is survived by his widow
and four sons Edward Jr., L. Frank, Harold E.,
and George A. O'Kelley.
FLORIDA STATE HORTICULTURAL SOCIETY
455
John Andrew Snively
James Arthur Griffin
John Andrew Snively, prominent in the Cit
rus Industry, and founder of Snively Groves,
Inc., died in Winter Haven, on January 22,
1958. Mr. Snively was born in Schellsburg,
Pennsylvania, on April 24, 1889, the son of
Laura May Irwin Snively and Frank Burns
Snively.
J. A. Griffin, noted banker, civic leader,
citrus grower, horticulturist, died on October
25, 1958, as a result of hip injuries received
in falling six weeks previously. He was 84
years of age.
As a young man, Mr. Snively worked in
the office of the Pennsylvania Railroad in
Altoona, Penna. In 1911, he married the
former Dorothy DeHaven and came to Florida
on his honeymoon. They were so enchanted
with Florida they never went back to Penn
sylvania except on visits.
Mr. Snively began his career in the Citrus
Industry and in Florida by selling Mapes
fertilizer. Almost immediately he started on
the ownership of his first citrus grove by
planting a 12 acre grove near Florence Villa.
He continued in the citrus business by selling
fertilizer and adding to his citrus holdings
until 1934, at which time he built his first
packing house located on the same property
the present modern building now stands. He
remained active in the processing, shipping
and growing of citrus fruit from that time
until his death.
At one time Mr. Snively was president of
the Florida Citrus Exchange, director of the
Tavares and Gulf Railroad, director of Ex
change National Bank of Winter Haven, mem
ber of the City Commission of Winter Haven,
and was instrumental in the organization of
Florida Citrus Mutual. He was also president
of the Cooperative Fruit & Vegetable Asso
ciation, Washington, D. C. He was a charter
member of the Rotary Club of Winter Haven,
a member of Egypt Temple of Tampa, Winter
Haven Commandery No. 37 Knight Templar,
and a Master Mason. Mr. Snively was always
associated with, and often headed, drives
for funds for the betterment of the community.
Mr. Snively is survived by his widow,
Dorothy DeHaven Snively, John A. Snively,
Jr., who is presently head of Snively Groves,
Inc., two daughters, Mrs. Robert Hoskins, Jr.,
and Mrs. I. C. Connor, Jr., and seven grand
children, two brothers and one sister in Flor
ida, H. B. and Thos. V. Snively, Mrs. W. W.
Giddings, and one brother and two sisters
in Pennsylvania, and one sister in Washington,
D. C.
Mr. Griffin was born at Fowltown, Ga.,
attended school in Marion County, Ga., and
entered the banking field as a clerk in Ocala,
Florida. He came to Tampa at the age of 21
in 1895 to work as a clerk in a bank. In 1902
he married Nannie Marshall Johnson. He was
made a cashier and director in 1903 and be
came active in management. He was named
vice president in 1920 and president in 1922.
During World War I Mr. Griffin headed the
bond selling campaign and received a citation
and silver trophy for the outstanding record
of Victory Bond sales in 1919. A high point
in his life came when he was named Out
standing Citizen of 1947 by the Tampa Civitan Club. At the time of his death he was
Chairman of the Board of the Exchange Na
tional Bank of Tampa, director of the Ex
change National Bank of Winter Haven, presi
dent and director of the Tampa Investment
and Securities Company, trustee of the Uni
versity of Tampa, and director of the Chil
dren's Home. He was closely associated with
the Community Chest, charter member of the
Tampa Rotary Club, director of the Florida
State Fair and past president of the Florida
Bankers' Association. Mr. Griffin was also
actively interested in Florida agriculture and
owned citrus groves. In 1928 during the first
Mediterranean fruit fly infestation he was the
spokesman for the citrus industry in a con
ference with Secretary of Agriculture Jardine
in seeking federal aid to combat the fly in
festation. Mr. Griffin was an active organizer
of Florida Citrus Mutual and was president
and director of Elfers Citrus Growers Associa
tion, and had been an active member of the
Florida State Horticultural Society for many
years.
Mr. Griffin is survived by his widow, four
sons, a daughter, three brothers, two sisters,
seven grandchildren and two greatgrandchil
dren.