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Group Title: Bulletin - University of Florida. Agricultural Experiment Station ; no. 362
Title: Relation of maturity in Bliss Triumph potato seed stocks to effectiveness of ethylene chlorhydrin and other treatments
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Permanent Link: http://ufdc.ufl.edu/UF00027124/00001
 Material Information
Title: Relation of maturity in Bliss Triumph potato seed stocks to effectiveness of ethylene chlorhydrin and other treatments
Series Title: Bulletin University of Florida. Agricultural Experiment Station
Physical Description: 40 p. : ; 23 cm.
Language: English
Creator: Townsend, G. R ( George Richard ), 1905-
Publisher: University of Florida Agricultural Experiment Station
Place of Publication: Gainesville Fla
Publication Date: 1941
 Subjects
Subject: Potatoes -- Seeds -- Testing   ( lcsh )
Ethylene   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Bibliography: p. 38-40.
Statement of Responsibility: by G.R. Townsend.
General Note: Cover title.
Funding: Bulletin (University of Florida. Agricultural Experiment Station) ;
 Record Information
Bibliographic ID: UF00027124
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: aleph - 000924595
oclc - 18230319
notis - AEN5222

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Full Text



September, 1941


UNIVERSITY OF FLORIDA
AGRICULTURAL EXPERIMENT STATION
WILMON NEWELL, Director
GAINESVILLE, FLORIDA









RELATION OF MATURITY IN BLISS
TRIUMPH POTATO SEED STOCKS TO
EFFECTIVENESS OF ETHYLENE
CHLORHYDRIN AND OTHER
TREATMENTS

By G. R. TOWNSEND






TECHNICAL BULLETIN







Single copies free to Florida residents upon application to
AGRICULTURAL EXPERIMENT STATION
GAINESVILLE, FLORIDA


Bulletin 362








EXECUTIVE STAFF
John J. Tigert, M. A., LL. D., President
of the University3
Wilmon Newell, D.Sc., Director3
Harold Mowry, M. S. A., Asst. Dir.,
Research
W. M. Fifield, M. S., Asst. to Director
J. Francis Cooper, M. S. A., Editor3
Clyde Beale, A.B.J., Assistant Editor3
Jefferson Thomas, Assistant Editor3
Ida Keeling Cresap, Librarian
Ruby Newhall, Administrative Manager3
K. H. Graham, Business Manager3
Rachel McQuarrie, Accountant3
MAIN STATION, GAINESVILLE
AGRONOMY
W. E. Stokes, M.S., Agronomist'
W. A. Leukel, Ph.D., Agronomist3
Fred H. Hull, Ph.D., Agronomist
G. E. Ritchey, M.S., Associate2
W. A. Carver, Ph. D., Associate
Roy E. Blaser, M.S., Associate
John P. Camp, M ., Assistant
Fred A. Clark, B.S.A., Assistant
ANIMAL INDUSTRY
A. L. Shealy, D.V.M., An. Industrialist' 3
R. B. Becker, Ph.D., Dairy Husbandman3
E. L. Fouts, Ph.D., Dairy Technologist3
D. A. Sanders, D.V.M., Veterinarian
M. W. Emmel, D.V.M., Veterinarian3
L. E. Swanson, D.V.M., Parasitologist
N. R. Mehrhof, M.Agr., Poultry Husb.3
W. M. Neal, Ph.D., Asso. in An. Nutrition
T. R. Freeman, Ph.D., Associate in Dairy
Manufactures
D. J. Smith, B.S.A., Asst An. Husb.3
P. T. Dix Arnold, M.S.A., Asst. Dairy
Husbandman-
L. L. Rusoff, Ph.D., Asst. in An. Nutr.3
L. E. Mull, M.S,, Asst. in Dairy Tech.
ECONOMICS, AGRICULTURE
C. V. Noble, Ph.D., Agr. Economist' 3
Zach Savage, M.S.A., Associate
A. H. Spurlock, M.S.A., Associate
Max E. Brunk, M.S., Assistant
ECONOMICS, HOME
Ouida D. Abbott, Ph.D., Home Econ.1
Ruth Overstreet, R.N., Assistant
R. B. French, Ph.D., Asso. Chemist
ENTOMOLOGY
J. R. Watson, A.M., Entomologistx
A. N. Tissot, Ph.D., Associate
H. E. Bratley, M.S.A., Assistant
HORTICULTURE
G. H. Blackmon, M.S.A., Horticulturist1
A. L. Stahl, Ph.D., Associate
F. S. Jamison, Ph.D., Truck Hort.3
R. J. Wilmot, M.S.A., Asst. Hort.
R. D. Dickey, M.S.A., Asst. Horticulturist
J. Carlton Cain, B.S.A., Asst. Hort.
Victor F. Nettles, M.S.A., Asst. Hort.
Lee B. Nash, Ph.D., Assistant
F. S. Lagasse, Ph.D., Asso. Horticulturist2
H. M. Sell, Ph.D., Asso. Horticulturist2
PLANT PATHOLOGY
W. B. Tisdale, Ph.D., Plant Pathologist1 a
George F. Weber, Ph.D. Plant Path.3
L. 0. Gratz, Ph.D., Plant Pathologist
Erdman West, M.S., Mycologist
Lillian E. Arnold, M.S., Asst. Botanist
SOILS
R. V. Allison, Ph.D., Chemist' 3
Gaylord M. Volk, M.S., Chemist
F. B. Smith, Ph.D., Microbiologist3
C. E. Bell, Ph.D., Associate Chemist
H. W. Winsor, B.S.A., Assistant Chemist
J. Russell Henderson, M.S.A., Associate3
L. H. Rogers, M.S., Asso. Biochemist
Richard A. Carrigan, B.S., Asst. Chemist


BOARD OF CONTROL
H. P. Adair, Chairman, Jacksonville
W. M. Palmer. Ocala
R. H. Gore, Fort Lauderdale
N, B. Jordan, Quincy
T. T. Scott, Live Oak
J. T. Diamond, Secretary, Tallahassee
BRANCH STATIONS
NORTH FLORIDA STATION, QUINCY
J. D. Warner, M.S. Agron. in Charge
R. R. Kinkaid, Ph.D., Asso. Plant Path.
Elliott Whitehurst, B.S.A., Assistant An.
Husbandman
Jesse Reeves, Asst. Agron., Tobacco
CITRUS STATION, LAKE ALFRED
A. F. Camp, Ph.D., Horticulturist in Chg.
John H. Jeffries, Asst. in Cit. Breeding
Chas. K. Clark, Ph.D., Chemist
V. C. Jamison, Ph.D., Soils Chemist
B. R. Fudge, Ph.D., Associate Chemist
W. L. Thompson, B.S., Associate Ento.
F. F. Cowart, Ph.D., Asso. Horticulturist
W. W. Lawless, B.S., Asst. Horticulturist
R. K. Voorhees, M.S., Asst. Plant Path.
EVERGLADES STA.. BELLE GLADE
J. R. Neller, Ph.D., Biochemist in Chg.
J. W. Wilson, Sc.D., Entomologist
F. D. Stevens, B.S., Sugarcane Agron.
Thomas Bregger, Ph.D., Sugarcane
Physiologist
G. R. Townsend, Ph.D., Plant Pathologist
R. W. Kidder, M.S., Asst. An. Husb.
W. T. Forsee, Ph.D., Asso. Chemist
B. S. Clayton, B.S.C.E., Drainage En-
gineer2
F. S. Andrews, Ph.D., Asso. Truck Hort.
SUB-TROPICAL STA., HOMESTEAD
Geo. D. Ruehle, Ph.D., Associate Plant
Pathologist in Charge
S. J. Lynch., B.S.A., Asst. Horticulturist
E. M. Andersen, Ph.D., Asst. Hort.
W. CENTRAL FLA. STA.,
BROOKSVILLE
W. F. Ward, M.S., Asst. An. Husband-
man in Charge2
RANGE CATTLE STA., WAUCHULA
W. G. Kirk., Ph.D., Animal Husbandman
in Charge
FIELD STATIONS
Leesburg
M. N. Walker, Ph.D., Plant Pathologist
in Charge
K. W. Loucks, M.S., Assistant Plant
Pathologist
Plant City
A. N. Brooks, Ph.D., Plant Pathologist
Hastings
A. H. Eddins, Ph.D., Plant Pathologist
E. N. McCubbin, Ph.D., Asso. Truck
Horticulturist
Monticello
A. M. Phillips, B.S., Asst. Entomologist2
Bradenton
Jos. R. Beckenbach, Ph.D., Truck Horti-
culturist in Charge
David G. Kelbert, Asst. Plant Pathologist
Sanford
R. W. Ruprecht, Ph.D., Chemist in
Charge, Celery Investigations
W. B. Shippy, Ph.D., Asso. Plant Path.
Lakeland
E. S. Ellison, Meteorologist2


'Head of Department
'In cooperation with U. S.
'Cooperative, other divisions, U. of F.






Relation of Maturity in Bliss Triumph Potato
Seed Stocks to Effectiveness of Ethylene
Chlorhydrin and Other Treatments
By G. R. TOWNSEND
CONTENTS
PAGE
Review of Literature ..... ...........- ..... ............. .. .... 4
The normal rest period ....................... ....... ... .. .........- 4
Physical methods for shortening the rest period..................... 6
Chemical methods for shortening the rest period...............----- 6
Factors influencing the productivity of seed stocks........................ 8
Seed-piece decay -.- .. ........-- .....--- --.......--...--......- 10
Experimental ..............................---------- ----- 11
Methods of testing the treatments and seed stocks................ 11
Results of experiments with dormancy breaking treatments............ 12
Results of experiments with supplementary treatments.... .... 26
Results of laboratory tests with deficient oxygen........... .... ..... 32
Discussion ....... ...... ..- .- .- -------------- --.... -- .. --. 33
Conclusions .. .. ...... ..... ... ... ...-- ....-. ...... 37
Literature Cited ........ ..... .. ............ ..... ... ....... ..... 38
INTRODUCTION
Approximately 3,000 acres in Palm Beach and Lee counties
are planted to potatoes in the fall. This crop must be planted in
September, or early in October, to avoid the danger of frosts in
December which would curtail production.
Bliss Triumph potatoes, which have not completed their
rest period, are planted when air temperatures range from 70
to 90' F., and soil temperatures vary between 75 and
850 F. Soil moisture is almost always adequate and may be
excessive, since the planting period comes at the end of the
summer rainy season. Heavy rains sometimes occur after the
potatoes have been planted. Because of the dormancy of the
tubers used for seed stocks the seed pieces often decay before
sprouting. When Denny (11) reported on his experiments with
ethylene chlorhydrin for hastening the sprouting of dormant
potatoes, it appeared that the principal problem in the produc-
tion of fall crop potatoes in Florida had been solved. It was soon
found that there was considerable variation in the results to
be obtained with the ethylene chlorhydrin treatment. Some
stocks of potatoes may respond to the treatment while others
fail to do so or are injured.
The larger problem of maturity in potato seed stocks has
evolved from simple tests with ethylene chlorhydrin for hasten-
ing sprouting, and of various supplementary fungicidal treat-
ments for the prevention of seed piece decay. A fuller apprecia-
tion of the problem and its solution can be obtained from
a comprehensive survey of the literature dealing with potato
seed stocks.

'Italic figures in parentheses refer to "Literature Cited" in the back
of this bulletin.






Relation of Maturity in Bliss Triumph Potato
Seed Stocks to Effectiveness of Ethylene
Chlorhydrin and Other Treatments
By G. R. TOWNSEND
CONTENTS
PAGE
Review of Literature ..... ...........- ..... ............. .. .... 4
The normal rest period ....................... ....... ... .. .........- 4
Physical methods for shortening the rest period..................... 6
Chemical methods for shortening the rest period...............----- 6
Factors influencing the productivity of seed stocks........................ 8
Seed-piece decay -.- .. ........-- .....--- --.......--...--......- 10
Experimental ..............................---------- ----- 11
Methods of testing the treatments and seed stocks................ 11
Results of experiments with dormancy breaking treatments............ 12
Results of experiments with supplementary treatments.... .... 26
Results of laboratory tests with deficient oxygen........... .... ..... 32
Discussion ....... ...... ..- .- .- -------------- --.... -- .. --. 33
Conclusions .. .. ...... ..... ... ... ...-- ....-. ...... 37
Literature Cited ........ ..... .. ............ ..... ... ....... ..... 38
INTRODUCTION
Approximately 3,000 acres in Palm Beach and Lee counties
are planted to potatoes in the fall. This crop must be planted in
September, or early in October, to avoid the danger of frosts in
December which would curtail production.
Bliss Triumph potatoes, which have not completed their
rest period, are planted when air temperatures range from 70
to 90' F., and soil temperatures vary between 75 and
850 F. Soil moisture is almost always adequate and may be
excessive, since the planting period comes at the end of the
summer rainy season. Heavy rains sometimes occur after the
potatoes have been planted. Because of the dormancy of the
tubers used for seed stocks the seed pieces often decay before
sprouting. When Denny (11) reported on his experiments with
ethylene chlorhydrin for hastening the sprouting of dormant
potatoes, it appeared that the principal problem in the produc-
tion of fall crop potatoes in Florida had been solved. It was soon
found that there was considerable variation in the results to
be obtained with the ethylene chlorhydrin treatment. Some
stocks of potatoes may respond to the treatment while others
fail to do so or are injured.
The larger problem of maturity in potato seed stocks has
evolved from simple tests with ethylene chlorhydrin for hasten-
ing sprouting, and of various supplementary fungicidal treat-
ments for the prevention of seed piece decay. A fuller apprecia-
tion of the problem and its solution can be obtained from
a comprehensive survey of the literature dealing with potato
seed stocks.

'Italic figures in parentheses refer to "Literature Cited" in the back
of this bulletin.






Florida Agricultural Experiment Station


REVIEW OF LITERATURE
The Normal Rest Period.-Potato tubers do not sprout for
several weeks after they have been harvested. The period in
which there is no visible evidence of growth is known as the
dormant period. Stuart (32) has pointed out that the dormant
period includes a rest period in which the tuber eyes do not
respond to natural growth stimuli (i. e., heat and moisture),
and a subsequent period in which the tubers remain inactive if
the natural stimuli to growth are lacking. The concern here is
only with the rest period.
The length of the rest period has been found to vary with
varieties (29, 32). Rosa mentions a yellow-fleshed Peruvian va-
riety which has no rest period. However, most varieties have
rest periods of several weeks. The Bliss Triumph variety has
a shorter rest period than the Irish Cobbler, but somewhat longer
than the Katahdin.
Rosa (29) and Werner (38) found that immature tubers re-
quired a longer rest period than mature tubers. Loomis (20)
noted that the larger tubers in a lot of seed were the first to
sprout.
Appleman and his co-workers (3, 4, 5, 6) studied the chem-
istry and physiology of potato tubers during the later period of
development and through the rest period. The storage of pro-
tein increased in the tubers until the leaves began to fall, but
decreased a little if the tubers were not harvested when the
vines were mature. There was little change in the protein con-
tent of tubers during the rest period. The total sugar content
was highest in immature tubers, and decreased considerably
during the rest period. Starch was highest in mature tubers
and did not change during the rest period. Non-protein nitro-
gen increased with maturity and during the rest period, except
for tubers harvested from dead vines. Minerals were slightly
lower in immature tubers, when harvested, but there were no
differences at the end of the rest period.
Water and carbon dioxide are lost from stored tubers
through the processes of evaporation and respiration. Apple-
man and Kimbrough (5) found that the loss of water was 20 to 30
times as areat in the first week after harvest as it was in the
fifth week. Appleman and Miller (6) found that tubers which
had been harvested while immature lost 16.45 percent in weight
during the rest period, but that mature tubers lost only 4.62 per-






Potato Seed Stocks


cent during the rest period. Werner (41) states that the evapora-
tion of water from stored tubers constitutes from 89 to 97 percent
of the total loss.
Smith (31) studied the respiration of potato tubers. When
the vines were still green and the tubers very immature the
rate of carbon dioxide production was more than double the
rate when the vines were dead and the tubers mature. There
was a sharp reduction in carbon dioxide production during the
first two weeks of storage.
Newton (25) found that amino and amide nitrogen com-
pounds are higher in non-dormant tubers. The activity of pro-
teolytic enzymes also was greater.
The anatomy of a tuber shows that it is an enlarged under-
ground stem. The characteristic epidermal layer of cells is re-
placed by a periderm layer. This is a compact layer of cells
whose walls become impregnated with suberin, a product form-
ed by the condensation and oxidation of fatty acids. The suber-
ized cell walls restrict the movement of water and gases. They
are highly important in maintaining the tubers in storage, and as
a protection against the invasion of disease organisms when
the tubers are planted.
Artschwager (7) found that the periderm begins to form
very early, and when the young tuber is the size of a pea it has
the number of cell layers characteristic of the variety. The Bliss
Triumph variety usually has six or seven cell layers in the
periderm. The formation of new periderm cells continues as a
function of the innermost layer of cells, and the outer layers
become corky and slough off. The periderm cells remain thin
walled, but become suberized by the deposition of fatty sub-
stances.
Thornton (34) has presented a slightly different picture of
the normal periderm. He found that the number of cell lay-
ers in the periderm increases considerably in the first two weeks
of storage. The ultimate thickness was about the same as Art-
schwager found, but most of the development occurred after the
tubers were harvested. He also found that the cell walls thick-
ened during storage. There was very little suberin in the cell
walls of the freshly harvested potatoes, but it increased particu-
larly in the outer layers of cells as the storage period was ex-
tended.






Florida Agricultural Experiment Station


The data cited by Appleman and Kimbrough (5), Appleman
and Miller (6) and Smith (31) show a progressive reduction in
the rates of evaporation and respiration, as the tubers become
more mature, and during storage. These data seem to confirm
Thornton's finding that the periderm thickens and becomes more
suberized during the later stages of tuber development and in
storage.
Physical Methods for Shortening the Rest Period.-Loomis
(20) showed that the rest period in Bliss Triumph tubers could
be shortened to four weeks if the tubers were held at 860 F. This
compares with a rest period of 15 weeks when this variety is
stored at 400 F. (42). Rosa (29) also found that several varieties
sprouted more rapidly when held in warm storage.
Rosa (29) held tubers at 720 F. and found that they sprouted
sooner when moisture was present than when stored dry. Wern-
er (38) hastened sprouting by planting the seed pieces in soils
having high moisture-holding capacities.
Appleman (4) hastened the sprouting of dormant tubers by
peeling them. The treatment was especially effective when the
skin around the eyes of the tuber was removed. This result was
attributed to increasing the permeability of the tuber to oxygen
and water by removal of the suberized periderm cells.
Chemical Methods for Shortening the Rest Period.-McCal-
lum (22) hastened the sprouting of dormant tubers by treating
them with ethyl bromide, ethylene dichloride and other chemi-
cals. Appleman (4) wrapped tubers with cotton moistened in
hydrogen peroxide. It was believed that the peroxide penetrat-
ed the tuber and liberated oxygen. Soaking the cut seed pieces
in solutions of sodium or potassium nitrate was reported to stim-
ulate sprouting by Rosa (27). Newton (25) found that while
nitrate nitrogen would stimulate sprouting, ammonium nitrogen
would not.
Denny (11) tested 224 different chemicals for their effects
upon the sprouting of dormant tubers. The chemicals tested
by McCallum and Rosa were not as effective as several other
materials. Ethylene chlorhydrin and the thiocyanates of sodium
and potassium gave very good results.
Three general methods for the ethylene chlorhydrin treat-
ments were employed by Denny. These were: (a) soaking cut
tubers for one or two hours in relatively weak solutions; (b)
gassing either whole or cut tubers by confining them for 16 to






Potato Seed Stocks


24 hours in a closed vessel in which ethylene chlorhydrin was
evaporating from shallow dishes, and (c) dipping cut tubers
momentarily in relatively strong solutions, and then confining
them for 16 to 24 hours.
In a second report (12) Denny recommended several ethy-
lene chlorhydrin treatments for Bliss Triumph potatoes. He
presented a range of concentrations and times of treatment since
it was recognized that potatoes grown in different localities or
which were in different stages of dormancy might respond dif-
ferently. The danger of over-treatment with the gassing meth-
od was recognized. Treatment of non-dormant tubers with the
thiocyanate salts was injurious.
Denny (13) showed that the temperature at which the seed
pieces are held following the ethylene chlorhydrin dip treat-
ment is important. Treated seed pieces held at temperatures
above 90 F. were injured. When the storage temperature was
590 F. or lower the response to the treatment was limited.
The gassing treatment was favored over the dip treatment
by Rosa (30) in California. When he dipped seed pieces in a
1:32 solution of ethylene chlorhydrin and stored them overnight,
considerable injury resulted. Summer temperatures prevailed
during his experiment. Rosa also found that ethylene gas treat-
ments were mildly effective.
Werner (38) showed that the dip treatment could be delayed
until 24 hours after the seed pieces were cut. When the period
between cutting and treatment was increased to 48, 96 and 144
hours sprouting was seriously retarded (as compared with treat-
ment within the first 24 hours) and the rotting of seed pieces
was increased.
The experiments conducted by Stuart (32) emphasize the
effects of variety and maturity upon dormancy. Bliss Triumph
tubers responded to the gassing treatment more rapidly than
Irish Cobblers. A very dormant stock of Dakota Red tubers re-
sponded to the dip treatment when the period of storage after
dipping was 36 hours, but the response was much less when the
storage period was only 12 hours.
Denny and Miller (15, 23) found that potato tubers absorbed
quantities of 0.1 M ethylene chlorhydrin up to 300 mg. per 100
grams of tissue when vapor treated. Part of this ethylene
chlorhydrin was given off as a vapor from the treated tubers,
and part was decomposed. The maximum amount of ethylene






Florida Agricultural Experiment Station


chlorhydrin which can be absorbed safely by dormant Irish Cob-
bler tubers is about 80 cc. 0.1 molar solution per bushel at 860
F. and somewhat higher at lower temperatures. They found
that absorption of ethylene chlorhydrin from solutions by cut
seed pieces was greatest when they are freshly cut, and decreas-
ed in the ratio of 100:74:57:22 for succeeding 24-hour periods
after cutting. Absorption of ethylene chlorhydrin from solu-
tions was not influenced by temperatures as much as the ab-
sorption from vapors.
Several studies have been made of the effect of ethylene
chlorhydrin on respiration in dormant potato tubers. Smith
(31) found that after the tubers have been treated there is a
large increase in carbon dioxide production. Miller et al (24)
found that this increase came about 10 hours after treatment.
Ward (35) found a very high rate of respiration in treated tubers
stored at 90-950 F. This rate was maintained until the tubers
underwent a complete physiological breakdown after 12 days.
The rate in untreated tubers was high at first, but declined after
a few days.
Thornton (33, 34) has an original hypothesis regarding the
rest period in potatoes. He maintains that dormancy exists in
freshly harvested tubers because they are too permeable to
oxygen. The rest period continues, according to this hypothesis,
until the periderm of the tuber thickens sufficiently to retard
the penetration of oxygen. He found that dormant tubers would
sprout much sooner when they were held in atmospheres con-
taining only 2 to 10 percent oxygen. When the tubers are
stored moist sprouting occurs at a higher oxygen level because
a more effective periderm is formed and excludes part of the
oxygen.
Factors Influencing the Productivity of Seed Stocks.-That
the maturity of a seed stock can influence its productivity the
following year was shown by Zavitz in Ontario (43). Stocks of
four ages were obtained by planting on May 31, June 14, June 28
and July 12. The following year these stocks produced 192, 195,
202 and 219 bushels per acre, respectively.
Martin (21) in New Jersey also found that immature stocks
were more productive than those that had reached full maturity.
In his experiments, the most mature stock yielded only 196 bush-
els per acre, while the least mature stock yielded 271 bushels
per acre.





Potato Seed Stocks


Werner (37) found that early harvested or late planted stocks
which were immature when harvested were most productive the
following year. He attributed this to a greater freedom from the
spindle tuber disease in the immature stocks. Later (40) he
worked with disease-free stocks and found that the immature
stocks were the most productive.
Wright and Peacock (42) found that potatoes which are
planted so as to mature during the heat of the summer have a
shorter rest period by one to six weeks than late planted pota-
toes that mature in November. Storage temperatures were not
a factor in shortening the rest period, since both lots were held
at 40 F.
Smith (31) found that early harvested Irish Cobbler and
White Rose tubers were more dormant than late harvested
tubers of the same varieties. A delay of six weeks in harvest-
ing shortened the rest period by six weeks.
Treatments with ethylene chlorhydrin hastened the sprout-
ing of all potatoes that had not completed their rest period in
Werner's experiments (38). Stocks that were most mature when
treated produced the greatest growth, but the greatest simula-
tion was obtained by the treatment of immature stocks.
Denny (12) obtained no response when a lot of Irish Cobbler
tubers were treated with ethylene chlorhydrin 10 days after dig-
ging. There was a slight response when these tubers were treat-
ed 22 days after digging, but it was not until 36 days after dig-
ging that a normal treatment response was obtained by the dip
method. The same lot of tubers responded to the vapor treat-
ment 22 days after digging and was injured by this treatment 36
days after digging.
Soil type and fertilizer practices may influence the produc-
tiveness of seed stocks. Hardenburg (16) reported that in New
York state potatoes produced on light, well aerated soils made the
most productive seed stocks. Albert et al (1) showed in 40 out
of 47 comparisons of peat and sand land grown seed stocks in
Wisconsin that the peat grown stocks were more productive in
the succeeding crop. Peat grown stocks showed particularly
good vigor shortly after emergence. In Montana, Harrington
(17) noted that the maturity of potatoes could be hastened or de-
layed by fertilizer practices. Nitrogen and potash delayed ma-
turity, while phosphorus hastened it and improved the texture of
the skins of the tuber. Werner (39) has shown that rotation
systems affect the value of a potato seed stock.






Florida Agricultural Experiment Station


Seed-Piece Decay.-When a potato is cut into seed pieces the
periderm layer, which is the tuber's natural protection against
invasion by disease-producing organisms, is broken. The expos-
ed cortical cells on the cut surface soon begin to form a new
protective layer-the wound periderm. Priestly and Woffenden
(26) say that this occurs rapidly. They found that within 24 to
48 hours a suberin layer was deposited in the walls of the sur-
face cells. This blocked the movement of water and soluble nu-
trients outward. Oxygen was needed for the proper formation of
the suberin block. In a moist atmosphere the suberin layer was
continuous, but if the cut surfaces dried too rapidly the suberin
block was not perfect. A few days after the suberin block was
formed the cells behind the blocked surface began to divide and
formed a wound periderm layer.
Artschwager (8) confirmed this work and showed that tem-
perature as well as moisture was important for the formation of
the suberin block. He found that at low temperatures suberiza-
tion required 10 days or longer. The rate of suberization was
most rapid at 70' to 86 F. Periderm cells formed on the second
day at 700 F. There were several rows of new cells by the third
or fourth day.
Herklots (18) found that the suberization process was fav-
ored by alkaline reactions. However, after a suberin block had
been produced the development of new periderm cells was fav-
ored by an acid reaction.
Seed-piece decay is an important factor when potatoes are
planted during the hot summer weather in California. Rosa (28)
found that the amount of decay was increased and the rest period
was prolonged by cutting the seed pieces several days before
planting.
The production of a fall crop of potatoes in Oklahoma is said
to be difficult because the seed pieces must be planted during
very hot weather. Cordner and Ward (10) found when soil tem-
peratures were high that seed piece decay was initiated by a
physiological breakdown similar to blackheart. Treatments which
favored the penetration of oxygen into the seed piece reduced
seed-piece decay. Freshly cut seed pieces were found to be bet-
ter than whole tubers, and paraffined or suberized seed pieces.
Prompt sprouting resulted in a lower loss of seed pieces. The
maximum temperature for sprouting was 900 F.
Alsobrook (2) conducted demonstration tests of the ethylene






Potato Seed Stocks


chlorhydrin treatment in Alabama during the summer of 1927.
When ethylene chlorhydrin treated seed pieces were dusted with
hydrated lime all of the seed pieces rotted. The treatment with-
out lime was successful.
Ethylene chlorhydrin vapors may be applied successfully to
whole tubers previously disinfected with mercuric chloride, mer-
curic oxide or formaldehyde, according to Denny (14). The
same treatments may also be given to whole tubers after the
vapor treatment. Whole tubers treated with mercuric chloride
or mercuric oxide cannot be cut and treated with ethylene
chlorhydrin by the dip method because decay is liable to follow.
Formaldehyde may be used safely in this way. In 80 percent of
Denny's tests, lots disinfected either before or after being gassed
showed slower sprouting than those not disinfected.
EXPERIMENTAL
Methods of Testing the Treatments and Seed Stocks.-The
experiments with ethylene chlorhydrin and supplementary fungi-
cidal treatments were conducted with Bliss Triumph potatoes.
Fall plantings were made about October 1 with seed stocks from
several states. Potatoes from the local fall crop were used for
spring plantings about February 15. Harvests of the fall crop
were made during the latter half of December and of the spring
crop early in May. All of the experiments were conducted on
peat soil at the Everglades Experiment Station, Belle Glade,
Florida.
The vapor and dipping treatments with thylene chlorhydrin*
were carried out approximately as outlined in the literature
review of Dr. Denny's work. Modifications of the treatments are
mentioned specifically in discussing the experiments. The fungi-
cide treatments were made according to the usual procedures for
hot and cold formaldehyde and mercuric chloride treatments,
and the manufacturer's instructions were followed for the other
fungicides.
The first experiments were begun simply as tests of the
ethylene chlorhydrin treatment and the plots were small and
were not replicated. Since 1935, however, the plots have con-
sisted of single rows of 100 to 158 hills replicated either four or
six times. The plots in the 1940 experiments were randomized

*The ethylene chlorhydrin used in these experiments was the 40
percent solution. Anhydrous (100 percent) chlorhydrin is now being
offered and may be used if proper adjustments in the concentration are
made.






Florida Agricultural Experiment Station


in six blocks so that an analysis of variance of the data could be
made. The prevailing practices with regard to fertilizer and
culture were followed.
The number of sprouted seed pieces observed at intervals
after planting was used to estimate the degree of dormancy and
the effectiveness of treatments. For fall planted stocks, counts
made two, three and four weeks after planting were sufficient
to obtain a complete picture of the development of sprouts. Seed
pieces which did not show emerged sprouts after four weeks
in the fall usually were found to be decayed. On the other hand
potatoes planted for the spring crop did not sprout so rapidly be-
cause of lower temperatures and drier soils. For these spring ex-
periments it was necessary to make the counts at longer intervals
after planting.
Yield records were taken when the vines began to die from
the early blight disease, or after the first killing frost. The
weights of all the tubers produced have been converted into
bushels per acre. Yields of U. S. No. 1 potatoes would be some-
what less than the total yields.
Results of the Experiments with Dormancy-Breaking Treat-
ments.-The discussion of the experimental results well may be
started with some tests which Dr. Denny conducted at the Ever-
glades Experiment Station in the fall of 1927". The tests were
conducted in the early fall when conditions were favorable for
seed-piece decay. Irish Cobbler potatoes from Maine and Bliss
Triumph potatoes from Maine and Nebraska were used in the
tests.
The Irish Cobbler stock was very dormant, as indicated by
the fact that less than 5 percent of the untreated seed pieces had
sprouted in three weeks. The most effective treatment was a
1:32 ethylene chlorhydrin dip of seed pieces that had been cut
for 24 hours. Treatment of freshly cut tubers was injurious, as
was also the storage of the treated seed pieces for 48 rather than
24 hours. Treatment of the freshly cut tubers with 1 and 2
percent sodium thiocyanate solutions for one hour was injurious.
All the seed pieces treated with the 2 percent solution rotted, but

'These tests were conducted by Dr. F. E. Denny of the Boyce Thomp-
son Institute in collaboration with the United States Department of
Agriculture. The writer is indebted to Dr. Denny and Mr. William
Stuart and Dr. E. C. Auchter of the Bureau of Plant Industry for per-
mission to cite these previously unpublished data.






Potato Seed Stocks


a V2 percent solution was about as effective as the ethylene
chlorhydrin treatment.
The Bliss Triumph stock from Maine was more dormant
than the same variety from Nebraska. Treatment of fresh-
ly cut seed pieces by either the gassing or dipping methods was
injurious, but gassing of seed pieces which had been cut for
24 hours was more effective than the similar treatment of whole
tubers. The best results with the Maine stock were secured with
the gassing treatment using one-half cubic centimeter of ethy-
lene chlorhydrin per liter of air space of the container in which
the tubers were treated, and the 1:32 ethylene chlorhydrin dip
treatment. Much better results were obtained with the ethylene
chlorhydrin dip treatments than with the thiocyanate treatments
on the Nebraska seed.
Two tests were conducted with locally grown Bliss Triumph
stocks in the springs of 1930 and 1931". Both tests demonstrated
the extreme dormancy of newly harvested tubers, and the neces-
sity of using cut seed pieces for the ethylene chlorhydrin dip
treatment. The gassing treatment was tried in the second exper-
iment and was more effective when prolonged for 48 hours.
Bliss Triumph tubers from the local fall crop were used for
a test of the ethylene chlorhydrin dip treatment in February,
1934. Three strengths of the treating solution were used to treat
freshly cut seed pieces. All of the treated seed pieces were
stored in hampers and covered with burlap sacks for 72 hours.
The response to the treatments was large and the 1:32, 1:16 and
1:8 concentrations of ethylene chlorhydrin solution were not in-
jurious to this very dormant seed stock.
A stock of Bliss Triumph potatoes from North Dakota was
used for an experiment beginning on October 17, 1934. The
stock was not very dormant, since an untreated lot and a lot treat-
ed before cutting sprouted readily. The 1:30 and 1:15 treat-
ments on freshly cut seed pieces caused decay. The best response
was obtained with the 1:120 solution on freshly cut seed pieces
and the 1:30 solution on whole tubers. There was more seed-
piece decay when the seed pieces were cut for 48 hours than
when freshly cut tubers were treated.
The potatoes used in the 1935 spring experiment had been
harvested from the experimental plots on December 14, 1934.

"These tests were conducted by the late H. H. Wedgworth, Associate
Plant Pathologist at the Everglades Experiment Station from 1930 to
1932.






Florida Agricultural Experiment Station


They were held in common storage until they were prepared for
planting on February 15, 1935. Several concentrations of the
ethylene chlorhydrin dip treatment were used on freshly cut
seed pieces and whole tubers. One test was made with seed
pieces that had been cut for 72 hours. Following the dip treat-
ment all of the treated seed pieces were stored in burlap cover-
ed baskets for 24 hours. Three lots of whole tubers were given
a gassing treatment with ethylene chlorhydrin.
Although this stock was very dormant, considerable seed-
piece decay followed the treatment of freshly cut seed pieces,
particularly with the 1:30 and 1:15 solutions. Nevertheless, the
yields were higher from the seed pieces given the stronger
treatments because of earlier growth of those seed pieces which
did not decay. The use of callused seed pieces retarded the
treatment effect, but did not result in as much decay. Treatment
of whole tubers by the dip method was ineffective. Gassing
whole tubers with one-half cubic centimeter of ethylene chlorhy-
drin per liter of space for 15 and 24 hours failed to give sufficient
stimulation.
Variations in the concentration of the ethylene chlorhydrin
dipping solution and in the handling of the cut seed pieces were
tested on a stock of Bliss Triumph potatoes from Maine in the
fall of 1935. Other tests were conducted with stocks from Wis-
consin and the Florida spring crop. The treated seed pieces were
stored in burlap covered baskets for 24 hours before planting.
The seed pieces were planted on October 3 and the tubers were
harvested on December 24. The data in Table 1 show that the
Wisconsin stock was superior to those from Maine and Florida
when similar treatments are compared. However, the Maine
stock was better with the weaker dip treatments. There was a
considerable reduction in sprouting caused by seed-piece decay
following the 1:30 and 1:15 dip treatments of freshly cut seed
pieces in this stock. The 1:30 treatment was not injurious to
whole tubers, nor to seed pieces that had been cut and held in
moist storage for 24 hours before treatment. The highest pro-
duction in the experiment was obtained from seed pieces that
were stored moist before treatment. Most of the seed pieces
that were dried before a fan and those that were submerged in
water for 24 hours before treatment decayed when planted. The
Florida stocks which were non-dormant were injured by the
treatments.






Potato Seed Stocks


TABLE 1.-PERCENT OF SEED PIECES WHICH SPROUTED AND YIELD OF POTATOES FROM
THREE SEED STOCKS WHICH HAD BEEX SUBJECTED TO ETHYLENE CHLORHYDRIN
DIP TREATMENTS IX THE FALL OF 1035.
Concentration
Source and Condition of of Ethvlene Percent Sprouted* Yield
Seed Pieces When Treated Chlorhydrin 3 Week 4 Weeks Bu. per A.
Maine-freshly cut 1:15 26.9 31.9 70.5
Maine-freshly cut 1:30 54.5 59.6 158.2
Maine-freshly cut 1:60 79.3 80.8 230.1
Maine-freshly cut 1:120 83.1 85.6 223.4
Maine-freshly cut None 40.1 76.6 168.9
Maine-whole tubers 1:30 69.9 87.2 224.7
Maine-cut seed pieces dried
before fan 24 hrs. 1:30 9.9 13.3 31.8
Maine-cut seed nieces moist
covered 24 hrs. 1:30 77.9 84.5 282.0
Maine-cut seed pieces sub-
merged in water 24 hrs. 1:30 1.1 1.6 5.3
Wisconsin-freshly cut 1:30 65.1 68.0 166.2
Florida**-freshly cut No. 1's 1:120 57.4 57.4 66.5
Florida-whole tubers No. 3's 1:30 47.7 47.8 101.0
Florida-whole tubers No. 3's None 65.1 68.1 131.7
*334 seed pieces planted for each treatment.
**The Florida stocks were from the spring crop; the large tubers had
been held in common storage and the number 3's in cold storage.
Potatoes harvested from the experimental plots on Decem-
ber 24, 1935, were used for the 1936 spring experiment, starting
February 17. Four concentrations of the ethylene chlorhydrin
dip treatment were tried on whole tubers, freshly cut seed pieces
and seed pieces that had been cut for 24 hours. All of the treat-
ed seed pieces were stored in burlap covered baskets for 24 hours
before they were planted. The data in Table 2 indicate that this
stock failed to respond to treatments before the tubers were cut.
On freshly cut seed pieces there was some injury with the 1:15
solution, but the weaker solutions stimulated sprouting and the
production of tubers. The seed pieces which had been cut for 24
hours before treatment were not injured by the stronger treat-
ments and the production was higher than for freshly cut seed
pieces similarly treated. The No. 3 seed was more dormant and
less productive than large seed.
Bliss Triumph potatoes from the Province of New Bruns-
wick, Canada, were used for an experiment starting on October
5, 1936. The treated seed pieces were stored for 24 hours be-
fore planting. Because of heavy rains in November, the only
data obtained in this experiment were the counts of sprouted
seed pieces in the fourth week from planting. The experiment
contributes further evidence of the interaction of treatment
strength with the method of handling the cut tubers. When







Florida Agricultural Experiment Station


TABLE 2.-PERCENT OF SEED PIECES SPROUTED, HEIGHT OF PLANTS AND YIELD FROM
SEED STOCKS TREATED WITH ETHYLENE CHLORHYDRIN BEFORE OR AFTER CUTTING
IN THE SPRING OF 1936.
Concentration
Condition of Seed of Ethylene Percent Sprouted* Height Yield
Pieces when Treated Chlorhydrin 4 Weeks 6 Weeks 4 Weeks Bu. per A.
Whole tubers 1:15 30 87 1-2 in. 219
Whole tubers 1:30 25 80 1-2 in. 186
Whole tubers 1:60 12 70 1-2 in. 169
Whole tubers 1:120 28 84 1-2 in. 179
Freshly cut 1:15 76 84 4-6 in. 188
Freshly cut 1:30 91 98 4-6 in. 236
Freshly cut 1:60 92 98 4-6 in. 236
Freshly cut 1:120 74 97 3-4 in. 224
Cut 24 hours 1:15 89 94 4-6 in. 254
Cut 24 hours 1:30 90 96- 4-6 in. 255
Cut 24 hours 1:60 87 99 4-6 in. 264
Cut 24 hours 1:120 67 97 2-3 in. 237
Cut 24 hours None 28 86 1-2 in. 222
Whole No. 3 tubers 1:60 1 41 1-2 in. 90
Whole No. 3 tubers None 0 24 1-2 in. 62
*632 seed pieces were planted for each treatment.

freshly cut seed pieces were treated with the 1:15 ethylene
chlorhydrin solution considerable decay resulted, but the same
solution was the most effective one for treating seed pieces that
had been cut for 24 hours. The data in Table 3 show that unless
a weak solution is used, it is better to allow the seed pieces to
heal for 24 hours before treatment.

TABLE 3.-PERCENT or SEED PIECES SPROUTED IN FOUR WEEKS WHEN FRESHLY CUT
AND CALLUSED SEED PIECES WERE TREATED WITH ETHYLENE CIILORHYDRIN IN THE
FALL OF 1936.
Concentration Percent Sprouted*
of Ethylene
Chlorhydrin Seed Pieces Cut 1 Hour Seed Pieces Cut 24 Hours
1:15 40.1 82.1
1:30 56.1 61.7
1:60 69.6 71.0
1:120 54.8 42.5
None 31.3
*632 seed pieces were planted for each treatment.

Bliss Triumph potatoes harvested locally on February 10,
1937, were replanted in an experiment starting February 19. The
stock proved to be extremely dormant and only one count of the
sprouted seed pieces was obtained before the experiment was
damaged by a flood in April. Although the percentages of
sprouted seed pieces were very low, differences due to the treat-
ments were evident. The 1:15 solution caused no injury to this
very dormant stock and it was the most effective treatment. The






Potato Seed Stocks


effectiveness of all the treatments was reduced when seed pieces
which had been cut for 24 hours were treated. The data are
shown in Table 4.
TABLE 4.-PERCENT OF SEED PIECES SPROUTED Ix EIGHT WEEKS WHEN FRESHLY CUT
AND CALLUSED SEED PIECES WERE TREATED WITH ETHYLENE CHLORHYDRIN IN THE
SPRING OF 1037.
Concentration Percent Sprouted*
of Ethylene
Chlorhvdrin Seed Pieces Cut 1 Hour Seed Pieces Cut 24 Hours
1:15 22.5 7.3
1:30 4.8 1.5
1:60 1.8 1.0
1:120 0.5 0
None-- 0.3
*400 seed pieces were planted for each treatment.
Ethylene chlorhydrin treatments on 12 Bliss Triumph seed
stocks from five states were compared in the 1937 fall experi-
ment. Stocks from Maine, Pennsylvania and Georgia were sup-
plied by cooperators who had produced stocks of varying but
specified maturity (growing period). The writer is indebted
to P. M. Lombard of the United States Department of Agricul-
ture Potato Laboratory, Presque Isle, Maine; A. C. Ramseyer of
Coudersport, Pennsylvania, and Elmo Ragsdale of the Georgia
Agricultural Extension Service, Athens, Georgia, for their ser-
vices in securing stocks which had been planted and harvested
at specified dates. Since the stocks with increasing maturity
had been obtained by delayed harvesting, the storage periods
were shorter for the more mature stocks. These special stocks
were held in common storage in the localities where produced
until they were shipped to Florida. The stocks from North Da-
kota and Tennessee were obtained locally and without complete
information as to their maturity.
Except where otherwise noted in Table 5, the treatments
were made on seed pieces that had been cut for 24 hours. The
dip treatments were given in the late afternoon and the seed
pieces were held in covered baskets overnight. The danger from
high day temperatures thus was avoided. The gas treatments
were made on whole tubers which were cut 24 hours ahead of
planting. The stocks from Maine, Georgia and Tennessee were
planted on October 1, 1937, and the Pennsylvania and North Da-
kota stocks were planted five days later.
The data obtained in this experiment are included in Table
5. Conclusions which may be drawn from these data are (a)







Florida Agricultural Experiment Station


TABLE 5.-PERCENT OF SEED PIECES SPROUTED AND YIELD FROM STOCKS OF POTATOES
FROM FIVE STATES, AND WITH DIFFERENT GROWING AND STORAGE PERIODS, WHEN
SUBJECTED TO ETHYLENE CHLORHYDRIN DIP AND GAS TREATMENTS IN THE FALL
OF 1937.


Source
of Se
Seed Stock
Maine
Maine
Maine
Maine
Maine
Maine
Maine
Maine
Maine
Maine
Maine
Maine

Pennsylvania
Pennsylvania
Pennsylvania
Pennsylvania
Pennsylvania
Pennsylvania
Pennsylvania
Pennsylvania
Pennsylvania

Georgia
Georgia
Georgia
Georgia
Georgia
Georgia
Georgia
Georgia
Georgia

N. Dakota U
N. Dakota U
N. Dakota U:

Tennessee 2
Tennessee A
Tennessee A
Tennessee -1
Tennessee A
Tennessee P


Days
ed Stock
Grew
85
85
85
92
92
92
99
99
99
106
106
106

98
98
98
105
105
105
112
112
112

102
102
102
109
109
109
116
116
116


Days Concentration
Stock of Ethylene
Stored Chlorhydrin
48 1:15
48 1:30
48 None
41 1:30
41 1:60
41 None
34 1:30
34 1:60
34 None
27 1:60
27 1:120
27 None

48 1:30
48 1:60
48 None
41 1:30
41 1:60
41 None
34 1:60
34 1:120
34 None

78 1:30
78 1:60
78 None
71 1:30
71 1:60
71 None
64 1:60
64 1:120
64 None


known Unknown 1:30
known Unknown 1:60
known Unknown None


bout 90
bout 90
\bout 90
about 90
bout 90
bout 90


About 80
About 80
About 80
About 80
About 80
About 80


1:60
1:120
None
1:60'
gassed"
gassed'


Per


2 Weeks 3
34.0
27.0
0.3
47.0
33.8
0.3
33.5
6.3
1.0
37.0
11.0
8.3

14.0
1.5
0.3
1.8
2.0
0.3
5.3
0.5
0

83.5
68.3
44.8
75.3
80.0
28.8
65.5
10.0
10.3

5.8
1.8
0

73.0
77.3
58.3
80.0
66.3
68.5


'400 seed pieces were planted for each treatment.
'Freshly cut seed pieces were treated.
"Whole tubers were gassed for five days with 1 cc. ethylene chlorhydrin
per pound.
4Same as (2) but 1/3 cc. anhydrous ethylene chlorhydrin per pound.
that the stocks from Georgia and Tennessee were much less
dormant than stocks from the Northern states, (b) that the date
of harvesting of the Georgia seed stocks had influenced their
dormancy and productivity, either because of the length of the


cent Sprouted' Yield
Bu.
Weeks 4 Weeks per Acre
73.0 73.3 191
74.5 73.3 207
40.3 59.0 132
85.3 85.5 239
87.3 89.8 221
40.5 62.5 138
85.8 87.5 240
60.8 62.5 147
35.5 57.5 112
89.8 90.3 206
63.5 64.8 151
56.0 62.8 152

33.0 35.8 73.7
20.0 36.8 54.2
3.5 14.5 20.1
15.0 20.0 47.4
19.8 32.8 35.7
6.5 30.8 31.2
28.3 39.3 66.4
12.5 26.0 35.2
1.5 11.8 16.2

94.5 94.5 254
90.3 89.3 229
91.8 91.8 246
86.8 86.8 238
93.3 93.3 269
83.8 84.8 214
92.0 91.8 266
70.8 75.8 181
51.0 62.0 132

17.8 31.3 49
9.0 21.5 15
1.3 13.5 14

86.0 86.5 225
92.5 93.0 251
83.5 83.8 231
82.8 82.3 255
70.3 70.5 180
73.5 73.0 190





Potato Seed Stocks


growing period or the storage period, or both, (c) that the
strength of the ethylene chlorhydrin solution should be gauged
by the maturity and storage period of the seed stock, (d) that
the treatment of freshly cut seed pieces induced more rapid
sprouting, but ultimately a poorer stand than the treatment of
suberized seed pieces and (e) that the gas treatments were less
effective than the dip treatments.
Bliss Triumph potatoes harvested from the experimental
plots on December 28, 1937, were used in an experiment starting
February 17, 1938. The interaction of the strength of the dipping
solutions with the method of handling the cut seed pieces was
investigated, and the data in Table 6 corroborate the previous
results. The 1:30 solution was somewhat injurious to freshly cut
seed pieces, while the 1:120 solution was not fully effective on
suberized seed pieces. The highest stands and yields in this ex-
periment were obtained by the treatment of freshly cut tubers.
TABLE 6.-PERCENT OF SEED PIECES SPROUTED AND YIELD WHEN FRESHLY CUT AND
SI'BERIZED SEED PIECES WERE TREATED \ITH ETHYLENE CHLORHYDRIN IN THE
SPRING OF 1038.
Treated 1 Hour Treated 24 Hours
After Cutting After Cutting
Concentration of Percent Yield Percent Yield
Ethylene Chlorhydrin Sprouted* Sprouted*
in 6 Weeks in 12 Weeks in 6 Weeks in 12 Weeks
1:15 80.2 293 bu. 92.2 353 bu.
1:30 98.2 369 bu. 94.2 343 bu.
1:60 98.0 364 bu. 93.0 341 bu.
1:120 92.5 347 bu. 82.0 279 bu.
None _65.0 230 bu.
*400 seed Dieces were planted for each treatment.
Bliss Triumph potatoes from Minnesota, Georgia, Tennessee
and North Carolina were used in the 1938 fall experiment. The
Minnesota stock was obtained from a local seed store, but the
other stocks were produced especially for this work. The Geor-
gia stocks were produced in one field from Canadian certified
seed by J. E. Bailey of the Georgia Mountain Experiment Station
at Blairsville, Georgia. These had been planted on successive
dates and all were harvested August 1, so that a range of grow-
ing periods from 80 to 140 days could be compared. W. J. Hilton
of Crossville, Tennessee, produced three stocks having growing
periods of 95, 100 and 105 days. These stocks had unequal stor-
age periods since they had been harvested on different dates.
Zeno Gettys of Ellenboro, North Carolina, produced two stocks
with growing periods of 89 and 104 days.





Florida Agricultural Experiment Station


The Minnesota stock was fully dormant, but the more ma-
ture Southern stocks had begun to sprout by September 26. All
of the Tennessee stocks had a few sprouts, and the 120 and 140
day Georgia stocks were sprouting, but the younger stocks were
still dormant when the treatments were made. Both of the
North Carolina stocks were well sprouted.
Two or more ethylene chlorhydrin dip treatments were
tested on each stock. Except where noted otherwise, the treat-
ments were applied to seed pieces that had been cut for 24 hours.
The data from this experiment are recorded in Tables 7 and 8.
The first table includes the Georgia stocks with different grow-
ing periods. All of these stocks had been in common storage
for eight weeks before planting. The growing periods and the
storage periods were variable with the stocks from Tennessee
and North Carolina. The growing and storage periods for the
Minnesota stock were unknown.
The more mature Georgia stocks were considerably less dor-
mant than comparable younger stocks, but none of these were
entirely non-dormant, since all of them responded to the ethyl-
ene chlorhydrin dip treatments (Table 7). The 1:30 treatment
was better than the 1:60 treatment for hastening the sprouting
of dormant stocks. The yields of treated stocks declined as the
maturity of the seed stocks increased.
The 100 day Tennessee stock was slightly more dormant
than either the 95 or 105 day stocks (Table 8). This may have
been due to the effect of a longer storage period for the 95 day
stock, and a longer growing period for the 105 day stock. None
of the Tennessee stocks were very dormant. The final stands
and yields indicated that the 1:30 treatment was somewhat in-
jurious, although better than no treatment. The 1:60 treatment
was more effective in stimulating sprouting and production in
the Tennessee stocks. The more mature North Carolina stock
showed some response to the dormancy treatment, perhaps be-
cause of a shorter storage period. However, the younger North
Carolina stock was more productive.
The Minnesota stock was extremely dormant, shown by a
germination of only 16.5 percent after four weeks (Table 8).
The response to the ethylene chlorhydrin dip treatments was
very marked, and the 1:30 treatment was superior to the weak-
er treatments. Treatment of freshly cut seed pieces stimulated
sprouting more rapidly than when suberized seed pieces were






Potato Seed Stocks


TABLE 7.-PERCENTAGE SPROUTED SEED PIECES AND YIELD FOR GEORGIA STOCKS OF
VARYING MATURITY WHEN TREATED WITH ETHYLENE CHLORHYDRIN IN THE FALL
or 1938.


Days
Seed Stock
Grew
80
80
80
85
85
85
90
90
90
95
95
95
100
100
100
110
110
110
120
120
120
140
140
140


Concentration
of Ethylene
Chlorhydrin
None
1:60
1:30
None
1:60
1:30
None
1:60
1:30
None
1:60
1:30
None
1:60
1:30
None
1:60
1:30
None
1:60
1:30
None
1:60
1:30


Percent Sprouted'


2 Weeks
6.2
35.5
43.5
3.0
27.5
35.5
6.5
52.7
71.7
29.0
52.7
65.0
7.5
38.5
59.0
22.7
39.7
70.5
51.0
77.7
80.7
66.2
87.5
87.2


3 Weeks
67.7
94.2
88.7
70.0
92.7
92.7
84.5
94.0
94.0
84.5
95.7
81.5
86.0
90.2
89.7
91.5
89.7
90.5
89.0
91.2
89.2
90.2
93.5
93.0


4 Weeks
84.2
95.5
90.2
87.2
95.2
94.2
88.0
93.7
94.2
85.2
95.5
85.2
88.7
93.5
89.7
91.5
93.0
90.2
91.2
91.0
88.2
91.7
93.7
92.2


Yield
Bu.
per Acre
172
236
219
190
225
244
209
241
221
204
235
187
177
196
215
188
198
187
153
192
165
181
165
179


*400 seed pieces planted for each treatment.
TABLE 8.-PERCENTAGE OF SPROUTED SEED PIECES AND YIELD FOR TENNESSEE, NORTH
CAROLINA AND MINNESOTA STOCKS OF VARYING MATURITY WHEN TREATED WITH
ETHYLENE CHLORHYDRIN IN THE FALL OF 1938.


day
day
day
day
day
day
day
day
day:
day
day
day
day
day
day


Concentration
of Ethylene
Chlorhydrin
None
1:60
1:30
None
1:60
1:30
None
1:60
s 1:30
None
1:120
1:60
None
1:120
1:60
None
1:120
1:60
1:30
1:602


Percent Sprouted'


2 Weeks
52.7
83.7
84.5
46.5
73.7
83.0
57.0
81.7
83.2
85.2
86.5
87.5
73.7
75.0
83.2
0.5
45.0
32.0
84.5
54.5


3 Weeks
86.5
95.2
92.5
86.7
95.5
92.7
87.7
95.5
91.0
91.5
95.7
94.5
92.0
90.7
92.7
4.5
86.0
79.5
96.3
75.0


4 Weeks
89.0
96.2
92.5
87.7
95.0
92.2
88.0
96.0
90.2
91.7
97.0
94.0
92.5
89.5
93.2
16.5
91.5
87.0
96.5
76.0


Bu.
per Acre
165
195
194
185
218
196
181
213
199
185
197
181
161
143
164
57
195
213
236
209


'400 seed pieces were planted for each treatment.
'Freshly cut seed pieces; all others had been cut for 24 hours.


Stock


Tenn. 95
Tenn. 95
Tenn. 95
Tenn. 100
Tenn. 100
Tenn. 100
Tenn. 105
Tenn. 105
Tenn. 105
N. C. 89
N. C. 89
N. C. 89
N. C. 104
N. C. 104
N. C. 104
Minnesota
Minnesota
Minnesota
Minnesota
Minnesota





Florida Agricultural Experiment Station


treated. However, the effect upon the ultimate stand was less
favorable when freshly cut seed pieces were treated.
A supplementary experiment was performed in the fall of
1938 to determine whether a period for suberization of the seed
pieces should intervene between cutting, treating and plant-
ing. A partially dormant North Dakota stock of Bliss Triumph
tubers was used for the experiment which was started on No-
vember 4. The percent of seed pieces sprouted and yields
(Table 9) were highest for the lot which was not treated but
which was allowed 16 hours for suberization before planting.
It did not matter whether the treatment was applied before
or after suberization of partially dormant seed pieces. However,
most of the seed rotted when freshly cut pieces were treated and
planted at once.
TABLE 9.-EFFECT OF SUBERIZATION OF SEED-PIECES UPON SPROUTING AND YIELD.
Percent Sorouted* Yield
Treatment 18 Days Bu. per
Acre
Suberized-16 hrs.-not treated 90.6** 90.5
Suberized-16 hrs. after 1:60 treatment 74.4 88.8
Suberized-16 hrs. before 1:60 treatment 70.2 86.7
Not suberized-1:60 treatment 1.7 0.9
*168-176 seed pieces planted for each treatment.
**The non-treated seed pieces sprouted later and the plants were one-
third the size of plants from treated seed pieces when these counts
were made.
The Georgia Mountain Experiment Station produced the
seed stocks for the fall experiment in 1939. All of the stocks were
grown in one field from a North Dakota certified stock. Planting
and harvesting dates were arranged to provide stocks with grow-
ing periods of 75 to 120 days, and storage periods of 61 and 81
days. All of these stocks were planted in this experiment on Oc-
tober 4. The 1:60 and 1:30 ethylene chlorhydrin dip treatments
were tested on each lot.
The percentages of sprouted seed pieces two weeks after
planting (Table 10) show that the immature stocks were con-
siderably more dormant than the older stocks when the storage
period was either 61 or 81 days. The ethylene chlorhydrin treat-
ments hastened the sprouting of all except the 120 day stock.
This stock was injured by both treatments. The stocks with the
shorter growing and storage periods showed large gains.
Yields were increased by treatment of the immature stocks, but
were considerably reduced by treatment of the most mature
stock. The 75 day stock was considerably more productive than
any of the more mature stocks.







Potato Seed Stocks


Nine stocks of Bliss Triumph potatoes were planted in the
1940 fall experiment. The Georgia Mountain Experiment Sta-
tion produced six of these stocks with specified growing and
storage periods. W. J. Hilton, of Crossville, Tennessee, produced
two stocks with different growing periods, and one North Da-
kota stock was obtained locally. This North Dakota stock had

TABLE 10.-PERCENT OF SPROUTED SEED PIECES AND YIELD FROM 15 GEORGIA SEED
STOCKS OF VARYING MATURITY WIIHEN TREATED WITH ETHYLENE CIILORHYDRIN
IN THE FALL OF 1939.
Days Days Concentration Percent Sprouted* Yield
Seed Stock Seed Stock of Ethylene Bu.
Grew Stored Chlorhydrin 2 Weeks 3 Weeks 4 Weeks per Acre
75 81 None 25.8 74.5 77.5 186
75 81 1:60 63.8 81.0 81.0 208
75 81 1:30 70.5 82.8 82.0 191
80 81 None 31.3 81.0 81.8 138
80 81 1:60 72.8 79.0 78.8 145
80 81 1:30 69.5 81.0 81.3 158
85 81 None 34.3 65.5 65.8 134
85 81 1:60 57.3 65.0 64.5 141
85 81 1:30 51.0 61.8 62.5 117
90 81 None 38.5 60.5 62.0 123
90 81 1:60 57.3 65.3 65.0 131
90 81 1:30 60.3 68.3 69.0 131
95 81 None 41.8 71.3 71.8 142
95 81 1:60 57.5 61.5 65.0 136
95 81 1:30 75.8 81.0 81.3 150
100 81 None 44.0 71.3 71.5 133
100 81 1:60 61.0 69.0 68.5 148
100 81 1:30 57.0 67.5 69.5 152
80 61 None 12.0 61.5 68.5 111
80 61 1:60 53.8 67.0 68.0 127
80 61 1:30 64.0 73.5 73.3 144
85 61 None 11.3 57.5 62.0 112
85 61 1:60 59.5 70.0 70.3 110
85 61 1:30 61.0 69.3 69.0 111
90 61 None 11.0 58.8 66.3 127
90 61 1:60 43.0 61.0 62.0 112
90 61 1:30 60.3 78.5 78.0 161
95 61 None 15.8 68.3 73.5 150
95 61 1:60 48.5 61.0 62.8 119
95 61 1:30 64.5 77.8 78.3 156
100 61 None 16.5 69.3 71.8 140
100 61 1:60 50.3 72.0 72.0 143
100 61 1:30 61.3 74.8 75.0 152
105 61 None 20.3 64.3 66.3 135
105 61 1:60 47.5 67.0 66.8 129
105 61 1:30 53.5 69.3 70.3 136
110 61 None 16.5 59.5 63.0 122
110 61 1:60 37.3 55.8 55.8 91
110 61 1:30 52.3 69.8 70.0 137
115 61 None 28.3 71.8 73.3 149
115 61 1:60 57.8 69.3 69.0 145
115 61 1:30 60.0 74.0 74.8 153
120 61 None 31.5 72.0 72.5 139
120 61 1:60 35.0 46.8 48.5 85
120 61 1:30 28.0 36.5 36.8 75
*400 seed pieces were planted for each treatment.






24 Florida Agricultural Experiment Station

been harvested less than two weeks, and had grown for more
than 110 days. Each of the stocks was divided into three lots
which were planted without treatment, and with the 1:60 and
1:30 ethylene chlorhydrin dip treatments, respectively, 24 hours
after cutting. There were six replications with 100 seed pieces
for each treatment of each stock. A randomized block layout of
the plots was employed, and the data have been analyzed for
variances.
The stocks which were harvested immature were more dor-
mant than stocks with longer growing periods (Table 11). Length-
ening the storage period reduced the dormancy in comparable
Georgia stocks. Two weeks' additional time in storage was more
effective in reducing dormancy than if the crop grew two or
four weeks longer. The North Dakota stock was extremely dor-
mant because of a short storage period, even though it had a long
growing period.
The productivity of Georgia stocks declined with advancing
maturity when they were harvested early enough to provide 78
days in storage (Tables 11 and 11a). When the storage period
was only 62 days the Georgia stocks increased in productivity
with advancing maturity. Comparable stocks from Georgia and
Tennessee were equally productive and greatly exceeded the
production of the very dormant North Dakota stock.
The ethylene chlorhydrin treatments hastened the sprouting
of all stocks (Tables 11 and llb) and increased the final stand of
all except the least dormant Georgia and Tennessee stocks.
There were indications of injury to the stand with the 1:30
treatment on the Georgia stock grown for 105 days and stored for
78 days, and with both treatments on the 108 day Tennessee
stock. Neither treatment was strong enough to develop a full
stand in the very dormant North Dakota stock. Yields were in-
creased by the treatments for all except the most mature Ten-
nessee stock.
A comparison of the gassing and dip methods of ethylene
chlorhydrin treatments was made in 1940. The test was made
with a partially dormant North Dakota stock planted on Novem-
ber 23. The seed pieces which were gassed were held in a closed
metal can with 2/3 cc. of ethylene chlorhydrin per pound of
tubers for 24 hours. Those which were cut after gassing were
aired for four days before cutting. The seed pieces which were
dipped were cut eight hours before the treatment with a 1:30
ethylene chlorhydrin solution. This stock sprouted most rapid-







Potato Seed Stocks


TABLE 11.-PERCENT OF SPROUTED SEED PIECES AND YIELD FOR GEORGIA, TENNESSEE
AND NORTH DAKOTA STOCKS OF VARYING MATURITY WHEN TREATED WITH ETIYL-
ENE CHLORIYDRIN IN THE FALL OF 1939.
Days Days Concentration Percent Sprouted* Yield
Source of Seed Stock Stock of Ethylene Bu.
Seed Stock Grew Stored Chlorhydrin 2 Weeks 3 Weeks 4 Weeks per Acre
Georgia 75 78 None 6.3 58.8 88.5 258
Georgia 75 78 1:60 53.7 91.6 96.5 284
Georgia 75 78 1:30 74.1 93.3 97.0 320
Georgia 90 78 None 16.5 64.5 86.7 246
Georgia 90 78 1:60 62.1 93.6 94.8 281
Georgia 90 78 1:30 69.3 92.8 95.8 305
Georgia 105 78 None 25.3 74.8 89.5 226
Georgia 105 78 1:60 70.5 92.0 96.6 277
Georgia 105 78 1:30 69.1 90.2 91.5 265
Georgia 75 62 None 1.5 13.3 41.3 136
Georgia 75 62 1:60 16.6 76.3 92.5 221
Georgia 75 62 1:30 43.8 89.8 97.0 238
Georgia 90 62 None 1.8 32.7 68.5 183
Georgia 90 62 1:60 28.5 87.5 94.5 267
Georgia 90 62 1:30 55.1 93.5 97.3 248
Georgia 105 62 None 5.1 48.3 73.8 200
Georgia 105 62 1:60 43.1 84.3 92.1 285
Georgia 105 62 1:30 58.3 89.8 92.5 279
Tennessee 90 69 None 1.8 28.7 76.8 204
Tennessee 90 69 1:60 26.5 82.6 95.3 253
Tennessee 90 69 1:30 38.6 82.3 87.5 240
Tennessee 108 69 None 6.8 62.5 81.8 237
Tennessee 108 69 1:60 43.3 69.8 75.0 234
Tennessee 108 69 1:30 37.8 70.8 77.3 245
North Dakota 110+ 13 None 0 0 0.6 9
North Dakota 110+ 13 1:60 0.1 1.5 5.2 37
North Dakota 110+ 13 1:30 2.0 16.0 32.0 132
Minimum significant difference 8.6 6.7 5.2 28.5
*600 seed pieces were planted for each treatment of each stock.
TABLE lla.-SrSMMARY or DATA FOR STOCKS Ix TABLE 11.
Percentage Sprouted* Yield

Stocks 2 Weeks 3 Weeks 4 Weeks Bu. per Acre
Georgia 75-78 55.0 81.3 94.0 287
Georgia 90-78 49.3 83.7 92.4 277
Georgia 105-78 44.7 85.7 92.6 256
Georgia 75-62 35.6 59.8 77.0 199
Georgia 90-62 28.5 71.2 86.8 233
Georgia 105-62 20.7 74.2 86.2 256
Tennessee 90-69 29.3 64.6 86.6 232
Tennessee 108-69 22.3 67.7 78.1 238
North Dakota 110+-13 0.7 5.8 12.6 59
Minimum significant difference 5.2 4.7 3.7 30.1
*1,800 seed pieces were planted for each stock.
TABLE llb.-SUAMMARY OF DATA FOR TREATArLFNTS IN TABLE 11.
Concentration Percentage Sprouted*
of Ethylene Yield
Chlorhydrin 2 Weeks 3 Weeks 4 Weeks Bu. per Acre
None 7.2 42.6 67.5 189
1:60 38.3 75.5 82.5 238
1:30 49.8 79.9 85.4 253
Minimum significant difference 3.1 2.2 1.7 9.5
*5,400 seed pieces were planted for each treatment.






Florida Agricultural Experiment Station


TABLE 12.-PERCENT OF SPROUTED SEED PIECES AND NUMBER OF STEMS PER SEED
PIECE, IN A COMPARISON OF ETIIYLENE CIILORHYDRIN GAS AND DIP METHODS FOR
TREATING DORMANT POTATO TUBERS.
Percent Sprouted Sprouts per
Number of Seed Piece
Treatment Seed Pieces 2 Weeks 3 Weeks 4 Weeks 3 Weeks
None 342 16.7 86.3 98.8 1.2
Gassed after cutting 311 28.6 80.7 89.4 1.8
Gassed before cutting 385 50.7 95.6 98.7 1.5
Dipped 337 84.6 99.4 99.7 2.3

ly and had the most sprouts per seed piece with the dip treat-
ment (Table 12). Gassing of whole tubers was successful, but
gassing of cut seed pieces was injurious.
Results of Experiments with Supplementary Treatments.-
Since the seed pieces for the fall crop of potatoes must be cut,
treated and planted during a period of high temperatures, and
also frequently of heavy precipitation, there usually is a consid-
erable loss of seed pieces. In most instances the decay of seed
pieces is caused by Fusarium species and bacteria. The organ-
isms are present on some tubers in most lots of seed arriving at
local warehouses, and probably are present also in all of our
soils. The methods of handling, treating and planting the pota-
toes are favorable to infection of the seed pieces by these organ-
isms. Part of the loss of seed pieces is not caused by these or-
ganisms directly, but may result from a physiological break-
down following overtreatment with ethylene chlorhydrin, or
under conditions favorable to the development of blackheart.
The experiments reported in this section were for the pur-
pose of determining whether certain fungicidal treatments could
be used to supplement the ethylene chlorhydrin treatment. Pre-
liminary tests indicated that a five minute dip treatment in
1:1,000 bichloride of mercury or 1:240 formaldehyde after the
dormancy treatment failed to control seed-piece decay. Other
tests with sulfur-dusted seed pieces and organic mercury treat-
ments were unsuccessful.
In an experiment started in October 1934 (Table 13) the
1:30 ethylene chlorhydrin treatment caused some loss of stand.
Seed pieces which were dusted with hydrated lime or sulfur fol-
lowing the ethylene chlorhydrin treatment decayed less than
untreated seed pieces. Supplementary dip treatments with 1:240
formaldehyde and 4-4-50 bordeaux mixture following the dor-
mancy treatment were injurious. The supplementary mercuric
chloride treatment was better than the dormancy treatment
alone, but no better than the untreated lot.






Potato Seed Stocks


TABLE 13.-PERCENT OF SPROUTED SEED PIECES AND YIELD WHEN ONE SEED STOCK
WAS TREATED WITH ETHYLENE CHLORHYDRIN AND SUPPLEMENTARY F INGICIDE
TREATMENTS IN THE FALL OF 1934.
Percent Sprouted* Yield Bu.
Treatments 3 Weeks per Acre
None 84.2 103
1:30 ethylene chlorhydrin dip 77.4 108
Ethylene chlorhydrin followed by:
Dusting sulfur 88.2 120
Wettable sulfur 85.7 94
Hydrated lime 98.2 109
1:1,000 Mercuric chloride 82.4 107
1:240 Formaldehyde 55.0 78
4-4-50 Bordeaux mixture 50.8 81
*57 to 70 freshly cut seed pieces were used for each treatment.
When a very dormant stock was planted in the spring of 1935
(Table 14) the 1:30 ethylene chlorhydrin treatment was not in-
jurious. Supplementary treatments with dusting sulfur and
hydrated limea appeared to be very helpful in preventing seed-
piece decay and increasing the yield.

TABLE 14.-PERCENT OF SPROUTED SEED PIECES AND YIELD WHEN ONE SEED STOCK
WAS TREATED WITH ETHYLENE CHLORHYDRIN AND SUPPLEMENTARY FUNGICIDE
TREATMENTS IN THE SPRING OF 1935.
Percent Sprouted* Yield Bu.
Treatment o Weeks oer Acre
None 1.8 12
1:30 ethylene chlorhydrin dip 22.9 75
Ethylene chlorhydrin followed by:
Sulfur dust 71.4 150
Hydrated lime 64.3 135
*70 freshly cut seed pieces were used for each treatment.
In the fall of 1935 (Table 15) a seed stock from Maine was
stimulated when treated with a 1:120 ethylene chlorhydrin solu-
tion, but was injured by the 1:30 treatment. Dusting with lime
following this treatment increased the loss of seed pieces and re-
duced the yield. A seed stock from Wisconsin was not injured
when a hot formaldehyde treatment of the whole tubers was
given 48 hours before the dormancy treatment. The yield was
increased by this treatment.

The hot formaldehyde and cold mercuric chloride treatments
48 hours prior to the dormancy treatment caused very slight re-
ductions in sprouting, but appreciable increases in yield in the
1936 spring experiment (Table 16). The seed pieces dusted with
sulfur and lime were injured, and the yields were reduced by
these treatments. Copper-lime dust was not injurious in this
test.






Florida Agricultural Experiment Station


The 1936 fall experiment was damaged by heavy rains in
November and the only data obtained were the counts of sprout-
ed seed pieces after four weeks. At time of planting it was noted
that the seed pieces which had been treated with formaldehyde
48 hours prior to the dormancy treatment were dry and were
healing properly. The untreated seed pieces also were healing
properly. All of the seed pieces which had been given mercury
treatments were discolored and slimy with a bacterial growth.
The degree of injury appeared to decrease with the treatments in
the following order: yellow mercuric oxide, mercuric chloride,
Mercurinol, Semesan Bel and Sanoseed. The first three are
inorganic mercury compounds.
The results of this experiment (Table 17) indicated little or
no damage to the seed pieces by the formaldehyde treatments
The inorganic mercury treatments were very injurious to the
seed pieces, but the organic mercurials were not harmful. Hy-
drated lime induced nearly complete rotting of the treated seed
pieces. Sulfur and copper-lime dust treatments also were in-
jurious.
TABLE 15.-PERCENTAGE OF SPROUTED SEED PIECES AND YIELD WHEN Two SEED
STOCKS WERE TREATED WITH ETHYLENE CHLORHYDRIN AND SUPPLEMENTARY
FUNGICIDE TREATMENTS IN THE FALL OF 1935.


P
Source of Seed and Treatment
Maine seed-none
Maine seed-1:120 ethylene chlorhydrin dip
Maine seed-1:30 ethylene chlorhydrin dip
Maine seed-1:30 ethylene chlorhydrin dip
followed by:
Hydrated lime
Wisconsin seed-1:30 ethylene chlorhydrin dip
Wisconsin seed-ethylene chlorhydrin
preceded by:
1:120 formaldehyde at 122 F.


percent Sprouted*
4 Weeks
76.6
85.6
59.6

37.2
68.0

70.0


Yield Bu.
per Acre
169
223
158

93
166


215


*334 freshly cut seed pieces were planted for each treatment.
TABLE 16.-PERCENTAGE OF SPROUTED SEED PIECES AND YIELD WHEN ONE SEED
STOCK WAS TREATED WITH ETHYLENE CHLORIIYDRIN AND SUPPLEMENTARY
FUNGICIDE TREATMENTS IN THE SPRING OF 1936.


Treatment
None
1:120 ethylene chlorhydrin dip
Ethylene chlorhydrin preceded by:
1:120 formaldehyde at 1220 F.
1:1,000 mercuric chloride at 65'
Ethylene chlorhydrin followed by:
Hydrated lime
Sulfur dust
20-80 Copper lime dust


Percent Sprouted*
6 Weeks
85.9
97.3


Yield Bu.
per Acre
222
224


95.9
F. 92.2


115
217
250


*632 freshly cut seed pieces were planted for each treatment.


--







Potato Seed Stocks


TABLE 17.-PERCENTAGE OF SPROUTED SEED PIECES WHEN ONE SEED STOCK WAS
TREATED WITH ETHYLENE CHLORHYDRIN AND SUPPLEMENTARY FUNGICIDE TREAT-
MENTS IN THE FALL OF 1936.
Percent Sprouted*
Treatment 4 Weeks
None 31.3
1:60 ethylene chlorhydrin dip 71.0
Ethylene chlorhydrin preceded by:
1:120 formaldehyde at 1220 F.-3 minutes 72.8
1:240 formaldehyde at 750 F.-105 minutes 69.7
1:1,000 mercuric chloride at 75 F.-105 minutes 52.7
Yellow mercuric oxide-1 lb. to 15 gal.-3 minutes 23.6
Semesan Bel-1 lb. to 7' gal.-3 minutes 64.1
Sanoseed-1 lb. to 7% gal.-3 minutes 76.4
Mercurinol-1 quart to 25 gal.-5 minutes 48.7
Ethylene chlorhydrin followed by:
Dusting sulfur 42.9
Hydrated lime 6.6
20-80 Copper-lime dust 53.0
*632 seed pieces were treated with each material. The ethylene
chlorhydrin treatments were made 24 hours after the tubers were
cut.
In the fall of 1937 the mercury treatments showed less in-
dication of injury than they did the year before. However,
when the counts of sprouted seed pieces were obtained it was
found that both the hot and cold treatments with mercuric
chloride and formaldehyde had reduced sprout development to
about the level of untreated seed pieces. The yields were also
reduced. (Table 18). Semesan Bel and Sanoseed did not in-
jure the seed pieces but did reduce the yield slightly. The com-
bination of ethylene chlorhydrin treatments with hot formalde-
hyde was very injurious in all of the concentrations tested.
The injurious effect of hot formaldehyde, hot mercuric
chloride and Semesan Bel solutions was not noted when the
ethylene chlorhydrin treatment was increased in strength from
1:60 to 1:30 in the 1938 spring experiment (Table 19). Sanoseed
was not injurious when followed by either dormancy treatment,
nor when mixed with the ethylene chlorhydrin, or applied after-
wards. Cold formaldehyde applied 48 hours before the dormancy
treatment was not injurious, but the cold mercuric chloride treat-
ment injured sprout development to some extent.
Three organic mercury compounds (Sanoseed, Semesan Bel
and Du Bay 1121-K) when mixed with the ethylene chlorhydrin
were very injurious to the sprouting of the seed pieces and the
yield in the 1938 fall experiment. (Table 20). The organic mer-
curials and formaldehyde applied before the dormancy treatment
were slightly injurious.







Florida Agricultural Experiment Station


TABLE 18.-PERCENT OF SPROUTED SEED PIECES AND YIELD WHEN ONE STOCK WAS
TREATED WITH ETHYLENE CHLORHYDRIN AND SUPPLEMENTARY FUNGICIDE TREAT-
MENTS IN THE FALL OF 1937.


Treatment


Percent Sprouted*
4 Weeks


Yield Bu.
per Acre


None 83.8 231
1:120 ethylene chlorhydrin dip 93.0 251
Ethylene chlorhydrin preceded by:
1:120 formaldehyde at 122 F.-21i minutes 83.8 214
1:240 formaldehyde at 790 F.-90 minutes 84.3 230
1:1,000 mercuric chloride at 1220 F.-2 minutes 82.3 210
1:1,000 mercuric chloride at 79" F.-90 minutes 83.3 196
Semesan Bel at 790 F. 1 lb. to 7 gal. 91.8 236
Sanoseed at 79" F. 1 lb. to 7% gal. 92.0 210
Ethylene chlorhydrin mixed with hot
formaldehyde:
1:120 formaldehyde-1:120 ethylene
chlorhydrin-2-% minutes 0 0
1:120 formaldehyde-1:240 ethylene
chlorhydrin--2' minutes 1.3 1.1
1:120 formaldehyde-1:480 ethylene
chlorhydrin--2% minutes 4.0 8.7
*400 seed pieces were used for each treatment. The ethylene chlorhydrin
treatments were given to seed pieces which had been cut for 24 hours.
TABLE 19.-PERCENTAGE OF SPROUTED SEED PIECES AND YIELD WHEN ONE SEED
STOCK WAS TREATED WITH TWO CONCENTRATIONS OF ETHYLENE CILORHYDRIN
AND SUPPLEMENTARY FUNGICIDE TREATMENTS IN THE SPRING OF 1938.
Percent Sprouted* Yield Bu.
Treatment 6 Weeks per Acre


None
1:60 ethylene chlorhydrin dip
1:60 ethylene chlorhydrin preceded by:
1:120 formaldehyde at 1220 F.-
2% minutes
1:1,000 mercuric chloride at 122 F.-
2 minutes
Semesan Bel at 70 F.-- Ib. to 7% gal.
Sanoseed at 70 F.-1 lb. to 7% gal.
1:30 ethylene chlorhydrin dip
1:30 ethylene chlorhydrin preceded by:
1:120 formaldehyde at 122 F.-2% minutes
1:1,000 mercuric chloride at 122 F.-
2 minutes
Semesan Bel at 700 F.-1 lb. to 7% gal.
Sanoseed at 70 F.-1 lb. to 72 gal.
1:240 formaldehyde at 70 F.-90 minutes
1:1,000 mercuric chloride at 700 F.-
90 minutes
1:30 ethylene chlorhydrin followed by:
Sanoseed at 70 F.-- lb. to 7% gal.
Sanoseed mixed with ethylene chlorhydrin:
Sanoseed 1 lb. to 7% gal.-ethylene
chlorhydrin 1:60
Sanoseed 1 lb. to 7% gal.-ethylene
chlorhydrin 1:30


65.0 230
93.0 341


368

333


*400 seed pieces were used for each treatment. The ethylene chlorhydrin
treatments were given to seed pieces that had been cut for 24 hours.
The experiment in the fall of 1940 was designed for a statis-
tical analysis of the influence of ethylene chlorhydrin and ethyl-






Potato Seed Stocks


TABLE 20.-PERCENT OF SPROUTED SEED PIECES AND YIELD WHEN ONE SEED
STOCK WAS TREATED WITH ETHYLENE CHLORHYDRIN AND SUPPLEMENTARY
FUNGICIDE TREATMENT 2IN THE FALL OF 193S.


Treatment
None
1:30 ethylene chlorhydrin dip
1:30 ethylene chlorhydrin mixed with:
Sanoseed
Semesan Bel
Du Bay 1121-K
1:30 ethylene chlorhydrin preceded by:
Sanoseed
Semesan Bel
Du Bay 1121-K
Hot formaldehyde


Percent Sprouted*
4 Weeks
16.5
96.5

53.2
45.2
65.7

89.2
88.0
89.2
88.5


*400 seed pieces were treated with each material. The ethylene
chlorhydrin treatments were given to seed pieces that had been cut
for 24 hours.
ene chlorhydrin following hot formaldehyde upon sprouting of
the seed pieces and yield. The interacting effects of these treat-
ments upon six stocks of Bliss Triumph potatoes are shown in
Table 21. Sprouting was stimulated in five of the six stocks by

TABLE 21.-PERCENT OF SPROrTED SEED PIECES AND YIELD WHEN SIX SEED STOCKS
WERE TREATED WITH ETHYLENE CHLORHYDRIN AND HOT FORMALDEHYDE IN THE
FALL OF 1040.


Stock
North Dakota A
North Dakota A
North Dakota A

North Dakota B
North Dakota B
North Dakota B

New York
New York
New York

Tennessee
Tennessee
Tennessee

Georgia A
Georgia A
Georgia A

Georgia B
Georgia B
Georgia B


Percent Sprouted'
Teratment 4 Weeks
None 11,4
Ethylene chlorhydrin' 61.8
Hot formaldehyde and ethylene
chlorhydrin" 58.3
None 85.0
Ethylene chlorhydrin 100.0
Hot formaldehyde and Ethylene
chlorhydrin 96.00
None 92.8
Ethylene chlorhydrin 96.8
Hot formaldehyde and ethylene
chlorhydrin 88.0
None 82.5
Ethylene chlorhydrin 93.3
Hot formaldehyde and ethylene
chlorhydrin 82.5
None 77.8
Ethylene chlorhydrin 95.3
Hot formaldehyde and ethylene
chlorhydrin 93.3
None 92.8
Ethylene chlorhydrin 9.3
Hot formaldehyde and ethylene
chlorhydrin 93.5
Minimum significant difference 4.4


'There were 400 seed pieces planted for each treatment.
'The 1:30 dip treatment was given seed pieces that had been cut for 24
hours.
'The whole tubers were dipped in a 1:120 formaldehyde solution at 122'
F. for three minutes. The seed pieces were cut on the following day
and the ethylene chlorhydrin treatment was given 24 hours later.


Yield Bu.
per Acre
57
236


Yield Bu.
per Acre
53
193

185
237
276

246
161
218

172
174
207

188
170
205

249
172
181

159






Florida Agricultural Experiment Station


the ethylene chlorhydrin treatment. The last stock listed was
not dormant when treated. The hot formaldehyde treatment
when followed within 48 hours by ethylene chlorhydrin reduced
sprouting of all but the non-dormant stock. This reduction was
significant for two stocks. Yields were increased by the ethylene
chlorhydrin treatment except in the non-dormant stock. Yields
were significantly lower where both treatments were given for
two stocks, and significantly higher for one stock.
The aggregate effect of these treatments upon all of the
stocks is shown in Table 21a. Here it is seen that the ethylene
chlorhydrin treatment is generally stimulatory and that the
treatment with hot formaldehyde followed by ethylene chlorhy-
drin usually reduces sprouting and yield. Since the hot for-
maldehyde treatment is primarily for the control of seed-borne
common scab, it is important to note that the treatment did not
control scab sufficiently to be recommended highly. It is also of
interest that the ethylene chlorhydrin treatment alone caused a
significant reduction in scab.
TABLE 21a.-AGGREGATE EFFECTS OF THREE TREATMENTS UPON SPROUTING, YIELD
AND SCABBINESS IN THE 1940 FALL EXPERIMENT.
Yield Bu. Percent
Treatment Percent Sprouted* per Acre Scab
None 73.7 161 43.9
Ethylene chlorhydrin 90.0 213 35.3
Hot formaldehyde and ethylene
chlorhydrin 85.2 200 24.2
Minimum significant difference 1.8 11.3 5.4
*2,400 seed pieces were planted for each treatment.
Results of Laboratory Tests with Deficient Oxygen.-The
hypothesis advanced by Thornton (34) to explain the rest period
in potato tubers seemed so novel that some simple laboratory
tests were conducted to check it. Since apparatus for controlling
gas mixtures was not available, other methods for limiting the
oxygen supply were tried.
Twenty-four newly harvested tubers were placed in a large
desiccator over a pyrogallol solution. A breaker of 5 percent
potassium hydroxide solution was placed in the desiccator to
absorb carbon dioxide and the desiccator was sealed. This treat-
ment proved to be too drastic, since the tubers began to decom-
pose within a week and had shrunk to a third of their original
volume within a month. It is thought that too much pyrogallol
solution was used and all of the oxygen was absorbed.
Eighty-five newly harvested tubers were coated with melt-






Potato Seed Stocks


ed paraffin to exclude air. These waxed tubers were then
subjected to the following treatments:
1. Twelve waxed tubers were heated in a Freas oven at 36
C. (98-100 F.) for seven hours and then were stored in a
sealed glass cylinder. These tubers decomposed nearly
as rapidly as those over the pyrogallol solution.
2. Twelve waxed tubers were heated at 36 C. for seven
hours and then stored in a paper bag on the laboratory
table. After 57 days two tubers were sprouting, three
were rotting and seven were dormant.
3. Twenty-four waxed tubers were placed in two sealed
glass cylinders without heating. These began to decom-
pose shortly after Lot 1, and all were rotten within a
month.
4. Thirty-seven waxed tubers were placed in a paper bag
on the laboratory table. After 57 days five tubers were
well sprouted, three were rotten and 29 were dormant.
As a check against the waxed tubers, 24 unwaxed tubers
were placed in sealed glass cylinders and 37 plain tubers were
stored in a paper bag. Since the inside walls of the cylinders
with the plain tubers became moist while the cylinders with the
waxed tubers remained dry, it was evident that the wax restrict-
ed the movement of water from the tubers. The tubers in one
cylinder were destroyed by Fusarium rot, but those in two other
cylinders remained sound and one tuber was sprouted after 57
days. None of the 37 unwaxed tubers stored in a paper bag
showed any signs of sprouting after 57 days.
DISCUSSION
The literature which has been reviewed and the experimen-
tal data recorded contribute to a fuller understanding of the
problem of productiveness in disease-free potato seed stocks.
The problem has particular importance in the Everglades where
dormant stocks are often planted under adverse conditions.
However, there are data recorded from other parts of the coun-
try which indicate that the same problem exists wherever pota-
toes are grown.
The potato tuber is a fleshy vegetative organ which is
physiologically active at all times. While the tuber is attached
to the plant and until the foliage begins to mature, the physiolog-
ical processes in the tuber are up-grade and there is storage of
proteins, carbohydrates, minerals and water in the growing tub-






34 Florida Agricultural Experiment Station

er. There is also a gradual replacement of the cuticle and epider-
mis of the young tuber by a thicker layer of periderm cells
which retard the movement of water and gases. The buds in the
eyes of the tuber are formed, but do not develop during this
period.
After the foliage begins to mature the production of car-
bohydrates and proteins declines and the balance of physiological
processes in the tuber changes from up-grade to retrograde.
There may be slight reductions in the protein, sugar and water
content of the tubers if harvesting is delayed.
When the tubers are harvested there is an immediate in-
crease in respiration and the evaporation of water. Probably as
a direct consequence of this increased activity the protective
periderm layer thickens and is reinforced by the deposition
of suberin in the walls of the outer periderm cells. The skin
of the tuber becomes corky and the activity of the tuber soon
subsides. The changes during the remainder of the rest period
are slight and purely retrograde. When the buds begin to de-
velop at the end of the rest period carbohydrates and proteins
are consumed at an accelerated rate.
The weight of opinion until very recently favored the hypo-
thesis that dormant potatoes would sprout when the protective
action of the periderm layer was broken down and oxygen
could penetrate to the buds. This seemed to be borne out by
experiments with cutting and peeling, treatment with hydrogen
peroxide, and the stimulation of respiration by chemical treat-
ments which broke the rest period. No one examined the nor-
mal periderm in dormant tubers or considered the implications
of the work on wound periderm formation by Artschwager in
this country, and Priestley and Woffenden in England. The
key to the whole problem appears to be Thornton's hypothesis
that dormant tubers will not begin to sprout until the periderm
layer is sufficiently thick to create a deficiency of oxygen in the
tuber. This is well supported by his anatomical studies of the
periderm and by forcing very dormant tubers to sprout quickly
by placing them in subnormal oxygen atmospheres. Simple lab-
oratory tests confirm this hypothesis.
The variability of the results with dormancy breaking treat-
ments is readily explained on the basis of the thickening of the
periderm and the readiness with which oxygen can penetrate the
tuber. In the immature tubers the periderm is thin and dorman-






Potato Seed Stocks


cy is deep. However, the stimulation of such tubers by the
ethylene chlorhydrin treatment results in an early growth of
strong sprouts because the reserve foods in the tuber have not
been impaired by a long period of retrograde reactions. When
harvesting has been delayed considerably the productiveness of
the tuber is impaired by retrograde reactions, but dormancy is
reduced by the thickening of the periderm. Sprouting of such
tubers occurs earlier than with immature tubers, but the growth
is not so vigorous nor the production so high.
The period of storage between harvesting and planting the
new crop also affects the degree of dormancy, since the periderm
continues to thicken and become more suberized during that
time. Tubers which have been stored for 70 days or longer, are
much less dormant than tubers of similar maturity that have
been stored for 60 days or less.
Although experimental evidence is lacking, it appears that
such factors as day length, soil type, fertilizer practices, irriga-
tion, and conditions of storage may have roles as important as the
length of the growing and storage periods in their effects upon
the productivity of potato seed stocks.
The practicability of the ethylene chlorhydrin dip method
for treating potato seed pieces to hasten sprouting has been dem-
onstrated in this series of experiments. There have been few
failures and many successes in treating more than 70 different
stocks of Bliss Triumph potatoes with ethylene chlorhydrin so-
lutions in over 10 years of testing. The ethylene chlorhydrin
treatment is valuable for the fall crop since, by hastening sprout-
ing, many seed pieces are saved from decay and the crop ma-
tures sufficiently early to avoid frosts in most years. When po-
tatoes from the fall crop are used as seed for the spring crop
it is necessary to use the dormancy treatment in order to start
growth early enough to produce a crop before hot weather pre-
vents tuber setting. The increases in stand of plants and yield
of tubers have varied with the stocks and seasons but have
generally been of considerable importance.
Failure of the treatment may result from either of two
causes. The dipping solution may be too weak to stimulate very
dormant tubers, or it may be so strong that the seed pieces are
injured. The selection of a treating solution of sufficient
strength to give good stimulation without injury to the seed
pieces requires some knowledge of the seed stock and how it






Florida Agricultural Experiment Station


may be affected by methods of handling, by temperature during
treatment, and by fungicides.
Immature stocks can be treated with much stronger solu-
tions than the more mature stocks. This probably is related to
their ability to generate a wound periderm over the surface of
the cut seed piece. If regeneration of the protective layer is
slow the seed piece literally may be burned up by excessive
respiratory activity following treatment. The danger of over
treatment in the fall may be reduced by allowing the cut tubers
to heal for 24 hours before treatment, by reducing the strength
of the treating solution, by shortening the period of storage after
treatment to 16 hours, and by treating late in the day so that
advantage of the lower night temperatures may be obtained.
Conversely, when very dormant seed stocks must be treated for
the spring planting freshly cut seed pieces may be treated with
strong solutions and the period of treatment may be extended.
The use of fungicides on the whole tubers or cut seed pieces
has not been found to be beneficial in reducing seed piece decay.
Although Fusarium spp. and bacteria are present in the rotting
seed pieces, the primary cause of the decay of treated seed pieces
probably is overstimulation of respiratory activity by the ethyl-
ene chlorhydrin solution. One remedy lies in improvements in
the treating operations to meet the need of the seed stock rather
than in the use of fungicides.
It sometimes has been observed that lime, sulfur, formalde-
hyde and the mercury fungicides increase the decay of sets. This
probably is related to the rapidity with which the wound
periderm can be generated and the effect of these chemicals upon
the generative cells.
The experiments have given clear indications of the greater
productivity of seed stocks which have been harvested somewhat
immature. This has been observed by others during the past 30
years, but has not received much attention. It is believed that
the same retrograde reactions which are responsible for the sen-
sitivity of mature seed stocks to the ethylene chlorhydrin treat-
ments are also responsible for the reduction in the productivity
of the stock. The solution of the problem so far as it affects
Florida growers would seem to be the production of immature
seed stocks by the growers of certified potatoes, and the recog-
nition by Florida growers of the importance of this factor.
Leach (19) has stated the aims of seed potato certification to






Potato Seed Stocks


be the production of stocks of seed tubers that are (a) true to
variety and type and (b) free from diseases that tend to reduce
the yield or quality of the resulting crop. It is the writer's be-
lief that a third requirement for certification should be adopted.
This might be stated as the ability of the seed stock to produce
in the area in which it is to be planted. Ware (36) and his asso-
ciates in Alabama have devised a system of testing certified seed
potatoes in order to reject low yielding stocks. The system un-
doubtedly assists their growers, but probably disqualifies a good
many stocks which would have been more productive if properly
handled by the seed producer. The problem really calls for ser-
ious consideration and cooperation by and among all the parties
interested in the production, certification and marketing of seed
potatoes.
CONCLUSIONS
1. The ethylene chlorhydrin dip treatment for hastening
sprouting of dormant potatoes increases the stand and yield of
most stocks of potatoes. The ethylene chlorhydrin gas treat-
ment and thiocyanate dip treatments are less successful.
2. For the fall crop in the Everglades, potatoes which have
been harvested early and stored for 10 weeks are more produc-
tive than potatoes which have been harvested late and stored for
four or five weeks. The immature seed stocks should be treated
with 1:30 ethylene chlorhydrin solutions to hasten sprouting. If
more mature stocks are to be planted, the 1:60 or even 1:120 so-
lutions should be used. All stocks will show some response to
the ethylene chlorhydrin treatment by earlier sprouting but the
less dormant stocks will not yield more tubers if treated.
The spring crop may be planted with stocks produced else-
where and no treatment will be required. However, if home-
grown tubers are used a strong ethylene chlorhydrin solution
should be used to treat them. If the seed stock has been harvest-
ed less than five weeks and the temperature has been low during
the storage period a 1:15 solution is safe and should be used.
All homegrown stocks should be treated with at least a 1:30 so-
lution for spring planting.
3. The danger from over-treatment may be avoided in the
following ways:
Select immature seed stock.
Use a concentration of the treating solution which is adapted
to the stock and the conditions of treatment.






Florida Agricultural Experiment Station


Apply the treatment to seed pieces which have been cut for
24 hours but not longer.
Shorten the treatment period to 16 hours and take advantage
of lower temperatures at night.
Cool storage at 650 to 750 F. during treatment is helpful.
4. Fungicide treatments sometimes interfere with the ethyl-
ene chlorhydrin treatment. Lime, sulfur and mercury treat-
ments are generally unsafe. Hot formaldehyde should be used
on whole tubers before the dormancy treatment if the stock is
affected with scab or Rhizoctonia. However, it is not a positive
control for scab because of soil infestation and generally causes
some reduction in yield.
5. Immature stocks which must be forced for early sprout-
ing are the most productive.
6. Seed brokers and growers who purchase large quantities
of seed potatoes for the fall crop should specify that they want
immature seed stocks which have been harvested for about 10
weeks if from the Southern states, and as long as possible if from
the Northern states. Southern stocks, if disease-free, are prefer-
able because they have been harvested longer.
7. Seed certification agencies in other states might cooper-
ate by determining the optimum length of the growing and stor-
age periods for stocks produced in their states. When this is
known the simple requirement that the certification label carry
the dates on which the stock was planted and harvested would
enable buyers to appraise the value of the stock for their pur-
poses.
LITERATURE CITED
1. Albert, A. R., R. H. Larson, and J. C. Walker. The comparative
productiveness of seed potatoes grown on sandy and on peat soils in Cen-
tral Wisconsin. Amer. Potato Jour. 16 : 16-24. 1939.
2. Alsobrook, Eric. Getting a stand of fall Irish potatoes. Progres-
sive Farmer and Farm Woman-Georgia-Alabama Edition. 43 : 768 A.
1928.
3. Appleman, C. 0. Changes in Irish potatoes during storage. Md.
Agr. Exp. Sta. Bul. 176 : 327-334. 1912.
4. Appleman, C. O. Study of rest period in potato tubers. Md.
Agr. Exp, Sta. Bul 183 : 181-226. 1914.
5. Appleman, C. 0., and W. D. Kimbrough. Physiological shrink-
age of potatoes. Proc. Potato Assoc. of America. 11 : 66-67. 1924.
6. Appleman, C. 0., and E. V. Miller. A chemical and physiological
study of maturity in potatoes. Jour. Agr. Res. 33 : 567-577. 1926.
7. Artschwager, Ernst. Studies on the potato tuber. Jour. Agr.
Res. 27 : 809-836. 1924.
8. Artschwager, Ernst. Wound periderm formation in the potato
as affected by temperature and humidity. Jour. Agr. Res. 35 : 995-100.
1927.






Potato Seed Stocks


9. Cordner, H. B. Seed preparation and cultural treatments in re-
lation to stand of plants in fall crop potatoes in Oklahoma. Proc. Amer.
Soc. Hort. Sci. 37 : 879-833. 1939.
10. Cordner, H. B., and Norman Ward. Germination and decay of
potato sets and tubers in controlled studies with especial reference to
high soil temperatures. Proc. Amer. Soc. Hort. Sci. 37 : 874-878. 1939.
11. Denny, F. E. Hastening the sprouting of dormant potato tubers.
Amer. Jour. Bot. 13 : 118-125. 1926.
12. Denny, F. E. Second report on the use of chemicals for hasten-
ing sprouting of dormant potato tubers. Amer. Jour. Bot. 13 : 386-396.
1926.
13. Denny, F. E. The importance of temperature in the use of
chemicals for hastening the sprouting of dormant potato tubers. Amer.
Jour. Bot. 15 : 395-404. 1928.
14. Denny, F. E. Combining treatments for disinfecting potato
tubers with treatments for breaking dormancy. Contr. Boyce Thomp-
son Inst. 9 : 397-402. 1938.
15. Denny, F. E., and L. P. Miller. Further experiments on short-
ening rest period of potato tubers. Contr. Boyce Thompson Inst. 7 :
157-181. 1935.
16. Hardenburg, E. V. Soil type as a factor in seed potato produc-
tion. Proc. Potato Assoc. of America 11 : 95-101. 1924.
17. Harrington, F. M. Influence of fertilizer on maturity and type
of potatoes. Proc. Amer. Soc. Hort. Sci. 33 : 560-562. 1935.
18. Herklots, G. A. C. The effects of an artificially controlled
hydrion concentration upon wound healing in the potato. New Phyto-
logist 23 : 240-255. 1924.
19. Leach, J. G. The Biological basis for certification of seed po-
tatoes. Amer. Potato Jour. 15 : 117-130. 1938.
20. Loomis, W. E. Temperature and other factors affecting the
rest period of potato tubers. Plant physiol. 2 : 287-302. 1927.
21. Martin, W. H. Potato experiments in New Jersey. N. J. Sta.
Rot. 1921. pp. 263-269. 1922.
22. McCallum, W. B. Ann. Rpt. Ariz. Agr. Exp. Sta. 1909 : 584-
586. 1910.
23. Miller, L. P., and F. E. Denny. Relation between quantity of
ethylene chlorhydrin absorbed and growth response in treatments for
shortening the rest period of potato tubers. Contr. Boyce Thompson
Inst. 8 : 121-136. 1936.
24. Miller, L. P., J. D. Guthrie and F. E. Denny. Induced changes
in respiration rates and time relations in the changes in internal factors.
Contr. Boyce Thompson Inst. 8 : 41-61. 1936.
25. Newton, William. Metabolism of nitrogen compounds in dor-
mant and non-dormant potato tubers. Jour. Agr. Res. 35 : 141-146.
1927.
26. Priestly, J. H., and L. M. Woffenden. The healing of wounds
in potato tubers and their propagation by cut sets. Ann. Appli. Biol. 10
: 96-115. 1923.
27. Rosa, J. T. Seed potatoes. Science 58 : 12. 1923.
28. Rosa, J. T. Some factors in preventing decay of potato sets.
Potato Assoc. Amer. Proc. 14 : 26-35. 1927.
29. Rosa, J. T. Relations of tuber maturity and of storage factors
to potato dormancy. Hilgardia 3 : 99-124. 1928.
30. Rosa, J. T. Effects of chemical treatment on dormant potato
tubers. Hilgardia 3 : 125-142. 1928.
31. Smith, Ora. Effects of various treatments on the carbon diox-
ide and oxygen in dormant potato tubers. Hilgardia 4 : 273-306. 1929.
32. Stuart, William. Shortening the rest period of the potato.
U.S.D.A. Tech. Bul. 415. 1934.
33. Thornton, N. C. Carbon dioxide storage. III. Relationship of
oxygen to carbon dioxide in breaking dormancy of the potato. Contr.
Boyce Thompson Inset. 10 : 201-204. 1939.






40 Florida Agricultural Experiment Station

34. Thornton, N. C. Oxygen regulates the dormancy of the potato.
Contr. Boyce Thompson Inst. 10 : 339-361. 1939.
35. Ward, Norman. The rate of respiration in potato tubers at
high temperatures in relation to treatment with ethylene chlorhydrin.
Proc. Amer. Soc. Hort. Sci. 37 : 871-873. 1939.
36. Ware, L. M. Certain aspects of the Alabama field tests of seed
potatoes as a requisite for certification. Amer. Potato Jour. 17 : 13-20.
1940.
37. Werner, H. O. Further report on environment relations to
quality in seed potatoes. Proc. Amer. Potato Assoc. 1-12. 1926.
38. Werner, H. O. The effect of maturity and ethylene chlorhydrin
seed treatment on the dormancy of Triumph potatoes. Nebraska Agr.
Exp. Sta. Res. Bul. 57. 1931.
39. Werner, H. O. Seed value of potatoes grown in different crop
rotations with irrigation. Amer. Potato Jour. 12 : 118-124. 1935.
40. Werner, H. 0., and L. L. Zook. Seed potato production in Cen-
tral Nebraska. Nebraska Agr. Exp. Sta. Bul. 294. 1935.
41. Werner, H. O. A review of the literature on the physiological
aspects of the storage of potatoes. Ann. Rpt. Neb. Pot. Improv. Assoc.
1934-1935, pp| 36-59. 1935.
42. Wright, R. C., and W. M. Peacock. Influence of storage tem-
peratures on the rest period and dormancy of potatoes. U.S.D.A. Tech.
Bul. 424. 1934.
43. Zavitz, C. A. Ontario Agr. Expt. Sta. Bul. 239. 1916.




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