December 1980
Horticulture Series No. 27
Auburn University
Agricultural Experiment Station
Gale A. Buchanan, Dean and Director
Auburn University, Alabama
-i.
RESEARCH RESULTS FOR ORNAMENTAL HORTICULTURISTS
Florist Crops
Horticulture Series No. 27
Auburn University Agricultural Experiment Station
Gale A. Buchanan, Dean and Director December 1980
Auburn, Alabama
CONTENTS
Rooting Response of Several Woody Ornamental Cuttings to Ethephon.
Kenneth C. Sanderson and Richard M. Patterson...............
Propagation of Azalea Cutting Treated with Chemical 
Pinching Agents
Prior to Rooting. Lih-Jyu Shu and Kenneth C. Sanderson.........
Further Studies on Atrinal on Azalea Plants: 
Concentration and
Cultivars. Kenneth C. Sanderson and Willis 
C. Martin, Jr..........
Chemical Pinching of Garden Chrysanthemums 
with Off-Shoot-0O, Tipnip,
Chemshear and UBI-P-293.Kenneth C. Sanderson 
and Willis C. Martin, Jr...
P age
1
5
10
13

Rooting Response of Several Woody
Ornamental Cuttings to Ethephon
Kenneth C. Sanderson and Richard M. Patterson
Auburn University Agricultural Experiment Station
Nature of Work:
Initiation of adventitious root primordia as well as the development of latent
pre-existing root initials have been achieved with ethylene gas and with saturated
aqueous solutions of ethylene mixed with IBA (14). Ethephon (2-chloroethyl phosphonic
acid) has been reported to both stimulate (9,10,12,13) and have no effect (8) on the
rooting of cuttings from herbaceous plants. Little information is available on
ethephon's value as a root-inducing substance for cuttings from woody plants. Ethephon
inhibited the rooting of Rosa sp. L. (13) but stimulated the rooting of Juniperus
chinensis Mast. cv. Pfitzeriana (19), Hibiscus Rosa-sinensis L. (9), and Salix
fragilis L. (6). Early research with ethephon on woody cuttings of azalea conducted
at Auburn, Alabama during 1969-72 (7, unpublished) also yielded inconsistent results.
The present study was conducted to evaluate the rooting response of woody ornamental
stem cuttings treated with ethephon from several other species.
Uniform cuttings, 15 cm long, of current season's growth were used in 2 experi-
ments. After removing the basal leaves, the lower 25 cm of the cuttings were either
not treated, soaked for 15 sec. in a liquid rooting substance or dipped in a rooting
powder. Propagation was carried out in a lightly shaded (about 40,365 lumenser m
2
)
glasshouse under mist (2.5 sec/100 sec) at a diurnal air temperature of 21-27 C
(thermostatical controlled heating cables). Equal parts of steam pasteurized builders
sand and sphagnum peat moss were used as a rooting medium. About 6 to 8 weeks after
insertion into the medium, the cuttings were evaluated for rooting as follows:
0 = dead, 1 = callused, 2 = callused, 3 = light rooting, 4 = medium rooting, and
5 = heavy rooting.
The first experiment was designed as a randomized complete block with 2 repli-
cations, 6 species or cultivars and 5 treatments. The experiment was initiated on
October 11, 10 cuttings per treatment of Ilex cornuta Lindl. cv. Burfordii, Ilex
cornuta Lindl. cv. Dwarf Burford, Juniperus conferta Parl., Osmanthus heterophyllus
(G. Don), Pittosporum tobira (Thunb.) Ait., and Rhododendron cv. Kingfisher. The
treatments are shown in Table 1. Rooting was evaluated on Nov. 29.
Significant differences in root-inducing treatments occurred only 
with
Osmanthus heterophyllus and Rhododendron cv. 
Kingfisher. Rooting of Osmanthus
cuttings treated with 1,000 ppm ethephon and Hormodin No. 2 was comparable and
exceeded untreated cuttings (Table 1). Rooting of Rhododendron 
was increased by
Hormodin No. 2 but not by ethephon.
The second experiment was a factorial experiment with 3 replications, 6
species and 9 treatments. Treatments consisted of all combinations of Jiffy Grow
No. 2 (a combination 5,000 ppm IBA, 
500 ppm NAA, 100 ppm phenymercuri acetate 
and
17.5 ppm boron) water mixtures 0, ll,and 1:4 with ethephon at 0, 500,and 1,000
ppm. A 2,000 ppm ethephon treatment was also included 
on each species in this
experiment. Camellia sasanqua Thunb., Ilex cornuta cv. Burfordii, Juniperus
conferta, Pittosporum tobira, Rhododendron 
cv. Kingfisher and Thuja occidentalis L.
cuttings were dipped for 15 sec. in each treatment 
prior to sticking on Feb. 13.
2
On April 17, rooting was evaluated as in the first experiment.
Results and Discussion:
Defoliation was observed on Camellia sasanqua cuttings within 24 hr. after
treatment with 2,000 ppm ethephon which continued until completely defoliated
within 1 week. Other ethephon treatments also dropped some camellia leaves.
Defoliation was not observed on untreated or Jiffy Grow - treated cuttings which
were randomly positioned among ethephon treated cuttings. The treatment with
2,000 ppm ethephon on Camellia cuttings was repeated with similar results using
alternate rows of treated and untreated cuttings. Inconsistant callusing was
observed on Camellia cuttings treated with 500 ppm ethephon and bark decay on the
treated area of Thuja cuttings receiving 1,000 ppm ethephon.
Rooting values differed for the 6 species as follows: Camellia, 3.7; Ilex,
2.9; Juniperus, 4.6; Pittosporum, 2.5; Rhododendron, 4.3; and Thuja, 2.9. There
was no statistically significant interaction between species and treatment.
Ethephon treatments were not significantly different in regard to rooting. Both
concentrations of Jiffy Grow No. 2 increased rooting of the 6 species.
Ethephon was an effective root-inducing substance for Osmanthus but produced
inconsistent results on Rhododendron and was ineffective for stimulating the root-
ing of other species. These results indicate that the effectiveness of ethephon
as a root-inducing substance is limited. Differential sensitivity to ethephon has
been observed in other test systems (5) and may similarly be involved in the root-
ing response. Root growth in Salix cuttings has been stimulated with greater con-
centrations of ethephon (1760 ppm) and a longer duration of treatment (24 hr.) than
used in the present study (6). Treatment time may be more critical than anticipated
in this study. Ethephon may act like ethylene in developing root initials (4)
and therefore be subject to the physiological state of the cutting, i.e., presence
of preformed root initials, buds, cambial dormancy, seasonal dormancy or growth
phase (11). Ethephon's release of ethylene is pH sensitive with greater amounts
of ethylene produced with increasing pH (3). Consequently, plant tissue pH may be
a factor in ethylene release. The presence or absence of natural auxin has been
reported to influence ethylene activity (4), and while not determined in this study
would be expected to vary between species. Ethylene also has been found to be a
normal intermediate in auxin-mediated root growth inhibition (2) which may be an
operative system in cuttings. Other changes are also ascribed to ethephon such as:
enzyme stimulation; mobilization of food reserves; inhibition of cell division;
auxin metabolism and transport and extension of cell expansion (1). Inducing these
changes may not be conducive to root growth or initiation (1). Further investigation
on these factors may explain the varying response of cuttings to ethephon as a
root-inducing substance and lead to its acceptance at least for certain species as
a root promoting growth regulator.
Table 1. Mean rooting scores of Osmanthus
Kingfisher stem cuttings treated
(Experiment 
1
)z
heterophyllus and Rhododendron cv.
with Hormodin No. 2 and Ethephon
Osmanthus Rhododendron
Treatment heterophyllus cv. Kingfisher
None 2.5 cd
y  
2.1 cd
Hormodin No. 2
x  
3.8 a 3.0 a
500 ppm Ethephon 1.9 d 2.3 bcd
1,000 ppm Ethephon 3.4 ab c. 1cd
2,000 ppm Ethephon 2.7 bcd 2.5 cd
z Rooting scroing: 0 = dead; 1
rooting; 4 = medium rooting;
Y Mean separation, in columns,
Numbers followed by the same
= alive, not callused; 2 =
5 = heavy rooting.
callused; 3 = light
by Duncan's multiple range test, 5% level.
letter(s) are not statistically different.
x 3,000 ppm IBA.
Literature Cited:
1. Burg, S. P., A. Apelbaum, W. Eisinger, and B. G. Kang. 1971. Physiology and
mode of action of ethylene. HortScience 6:359-363.
2. Chadwick, A. V. and S. P. Burg. 1970. Regulation of root growth by auxin-
ethylene interaction. Plant Physiol 45:192-200.
3. Cooke, A. R. and D. I. Randall. 1968. 2-haloethanephosphonic acids as ethy-
lene releasing agents for the induction of flowering in pineapples. Nature
218:974.
4. Hitchcock, A. E., and P. W. Zimmerman. 1940. Effects obtained with mixtures
of root-inducing and other sustances. Contr. Boyce Thompson Inst. 11:143-160.
5. Kamienska, A., and A. Chrominski. 1971. Auxin-like activity of (2-chloro-
ethyl) phosphonic acid. Bot. Gaz. 132:229-232.
6. Kawase, M. 1971. Causes of centrifugal root promotion. Physiol. Plantarium
25:64-70.
7. Nell, T. A., and K. C. Sanderson. 1972. Effect of several growth regulators
on the rooting of three azalea cultivars. Florists' Rev. 150:21-22, 52-54.
8. Read, P. E., and V. Hoysler. 1969. The effect of several growth regulating
chemicals on the rooting of cuttings of several ornamental species. Hort-
Science 4:171.
9. Read, P. E., R. J. Henny, and D. A. Heng. 1970. Comparison of commercial
auxin-like chemicals with other growth regulators for stimulation of rooting
of cuttings. HortScience 5:320.
10. Read, P. E., and V. Hoysler. 1971. Improving rooting of carnation and poinsettia
cuttings with succinic acid 2,2-dimethyl hydrazide. HortScience 6:350-351.
11ii. Roberts, A. N., and L. H. Fuchigami. 1973. Seasonal changes in auxin effect
on rooting of Douglas-fir stem cuttings as related to bud activity. Physiol.
Plant 28:215-221.
12. Samananda, N., D. P. Ormrod, and N. 0. Adedipe. 1972. Rooting chrysanthemum
stem cuttings as affected by (2-chloroethyl) phosphonic acid and indole-
butyric acid. Ann. Bot. 36:961-965.
13. Shanks, J. B. 1969. Some effects and potential uses of ethrel on ornamental
crops. HortScience 4:56-58.
14. Zimmerman, P. W., and A. E. Hitchcock. 1933. Initiation and stimulation of
adventitious roots caused by unsaturated hydrocarbon gases. Contr. Boyce
Thomp. Inst. 5:351-369.
Propagation of Azalea Cuttings Treated with Chemical Pinching Agents
Prior to Rooting
Lih-Jyu Shu and Kenneth C. Sanderson
Auburn University Agricultural Experiment Station
Nature of Work:
Removal of the terminal portion of the plant or "pinching" is a common com-
mercial practice in the propagation of azaleas, Rhododendron cultivars, to in-
fluence axillary shoot development. Chemical pinching agents can perform this
task, however, until recently, most chemical 
pinching agents destroyed plant
tissue (4) and increased the risk of disease. Atrinal
T
, a new chemical pinching
agent has been found to increase branching in azaleas without destroying plant
tissue (2,3,5). Cohen (1) has reported that the treatment of azalea stock plants
with AtrinalTM does not affect the rooting percentage of azalea cultivars. Shu
and Sanderson (6) applied several chemical pinching agents to cuttings 3 weeks
after placement in the propagation bench and found that untreated cuttings produced
more roots than chemical treatments. Also, chemical pinching agent treatment
generally did not increase the number of shoots on cuttings.
Objectives of the present study were to determine: (1) the effects of several
chemicals applied to stock plants on subsequent rooting of cuttings (Experiment
1) and (2) to further evaluate the application of chemical pinching agents to
cuttings in the propagation bench (Experiment 2).
Experiment 1. Azalea stock plants, cv. 'Prize', were sprayed on June 21,
1979 with the following chemicals: 0.50% Atrinal
TM
, 0.25% AtrinalT
M
, 4.20% Off-
Shoot-OTM, 1.00% UBI-P293 (oxathiin), 0.50% Chemshear
TM , 
0.48% Ethrel
T M 
(ethephon),
2.50% Ti nipTM, 0.08% AccelTM (PBA), 0.50% B-Nine
T M
, 0.30% Cycocel, and 2.50%
Royaltac
T M
. A check or no treatment was included for comparison and treatments
were applied in a randomized block design consisting of 1 plant per treatment and
5 replications. Nine weeks after spraying the stock plants, 10 cuttings were
randomly removed from each stock plant and propagated in mason's sand. A root
inducing substance consisting of 1:1 (V/V) Hormodin
TM 
No. 3 and ferbam was applied
to the base of all cuttings. Bottom heat (22.2
0
C or 72
0
F) and automatic mist (5
seconds per 5 minutes) were applied to the propagation bench. The experimental
design was a randomized block with 12 treatments, 10 cuttings per treatment and
5 replications. Rooting was indexed from dead (0) to heavy rooting (8) 7 weeks
after placement of the cuttins in the propagation medium.
Experiment 2. Cuttings of azalea cv. 'Kingfisher' and 'Prize' were propagated
in mason's sand. A root inducing substance consisting of 1:1 (v/v) Hormodin
TM
No. 3 and ferbam was applied to the base of all cuttings. Bottom heat 22.2
0
C
(72oF) and automatic mist system (5 seconds per 5 minutes) were applied to the
propagation bench. The experimental design was a randomized block with 10 treat-
ments, 10 cuttings per treatment and 5 replications. Cuttings were sprayed with
2.50 % TipnipT
M
, 2.50% RoyaltacTM, 0.48% EthrelTM (ethephon), 0.50% Chemshear
T M ,
1.00% UBI-P293 (oxathiin), 0.08% AccelT
M 
(PBA), 1.20% Off-Shoot-0
T M 
and 0.50%
Atrinal
T M 
(dikegulac sodium) 3 weeks after the cuttings were placed in the propaga-
tion media. A non-treatment check was included for comparison. Seven weeks after
treatment new shoot numbers were counted and the amount of rooting was indexed
from dead (0) to heavy rooting (8).
Results and Discussion:
Experiment i. Chemical treatment of stock plants prior to subsequent propa-
gation of cuttings did not statistically influence rooting (Table 1). This result
agrees with that of other workers (1,4). One week after treatment, ChemshearTM
stock plants appeared wilted and some leaves had turned brown. Three weeks after
stock plant treatment, some chemically treated shoots exhibited axillary shoot
development.
Treatment of cuttings with Tipnip
TM , 
RoyaltacTM, EthrelTM, ChemshearTM
AccelTM, 4.20% Off-Shoot-OTM and 2.10% Off-Shoot-OTM during propagation, resulted
in the destruction of plant tissue within 2 weeks. All chemical treatments except
Off-Shoot-OTM and TipnipTM showed axillary shoot development at this time. Check
plants exhibited new leaves. Leaves of AtrinalTM-treated cuttings had a reddish
coloration. The application of Royaltac
TM
, and 4.20% Off-Shoot-O
TM 
during propa-
gation reduced the number of shoots per cutting of both cultivars (Table 2). Tip-
nipTM and ChemshearTM treatments reduced the number of shoots on 'Kingfisher'
cuttings while UBI-P293 and AccelTM reduced the shoot number of 'Prize' cuttings.
With both cultivars, Atrinal-treated cuttings had the same number of shoots statis-
tically as the untreated cuttings. The chemical pinching agents at the concentra-
tions tested in this study do not seem to increase the shoot number of cuttings
during propagation. The use of Atrinal
TM 
should be re-examined for its influence
on the type of axillary shoot development and plant size obtained. Tipnip
TM
RoyaltacTM, EthrelTM and Off-Shoot-OTM treatments reduced the rooting of cuttings
for both cultivars. ChemshearTM treatments reduced the rooting of 'Kingfisher'
cuttings but not 'Prize' cutting AccelTM-treated 'Prize' cuttings had lower rooting
indexes than the check. ChemshearTM reduced the rooting of 'Kingfisher' cuttings
but not 'Prize' cuttings. These results agree with a previous study (6) that showed
that chemical pinching agents do not enhance the rooting of azalea cuttings.
Table 1. Rooting Index of 'Prize' Azalea Cuttings
Taken from Stock Plants Treated with
Various Chemical Pinching Agents and Re-
tardants
Treatment Rooting indexZ
Atrinal 0.50% 5.9 a
y /
Atrinal 0.25% 6.3 a
Off-Shoot-O 4.20% 6.4 a
UBI P-293 1.00% 5.8 a
Chemshear 0.50% 6.2 a
Ethrel 0.48% 6.1 a
Tipnip 2.50% 6.3 a
PBA 0.08% 5.8 a
B-Nine 0.50% 5.9
, 
.a
Cycocel 0.30% 6.3 a
Royaltac 2.5% 6.5 a
Check 6.1 a
- Rooting was indexed 
from 0 (dead) to 
8 (heavy
rooting).
i/Mean separation in columns by Duncan's multiple
range test, 5% level.
8
Table 2. New Shoot Number and Rooting Index of Azalea Cuttings 
Sprayed
with Chemical Pinching Agents During Propagation
Treatment
Tipnip 2.50%
Royaltac 2.50%
Ethrel 0.48%
Chemshear 0.50%
UBI-P293 1.00%
PBA (Accel) 0.08%
Of f-Shoot-0 2. 10%
Off-Shoot-0 4.2%
Atrinal 0.50%
Check
Kigisher
5.0 bcil
5.4 bc
8.2 ab
5,8 b
8.4 ab
8.2 ab
6.2 ab
2.0 c
10.8 a
10.2 a
Prize
8. 8 abc
8.0 bc
10. 2 abc
11. 6 a
8. 0 bc
7.4 c
11. 4 a
7. 8 bc
11.6 a
11.0 ab
Kingfisher
1.7 d
3. 9 c
4. 2 be
4.7 bc
5.6 ab
5.3 abc
3.9 c
1.1 d
5. 6 ab
6. 6 a
Prize
3. 9 d
4.2 dc
4. 2 dc
6.8 a
6. 0 abc
4. 7 bcd
4. 7 bcd
4.6 bcd
6. 1 ab
6.5 a
ziRooting was indexed from 0 (dead) to 8 (heavy rooting).
X2"Nean separation in columns by Duncan's multiple range test, 5% level.
9
Literature Cited:
1. Cohen, M. A. 1979. Effect of Atrinal on branching and rooting of azaleas.
Proc. SNA Res. Confr. 24:208-209.
2. DeSilva, W. H., P. F. Bocion and H. R. Walther. 1976. Chemical pinching
of azaleas with dikegulac. HortScience 11:569-570.
3. Heursel, J. 1975. Results of experiment with dikegulac used on azaleas
(Rhododendron simsii Planch). Med. Fac. Landbouw Rijksuniversiteit Ghent
40:849-857.
4. Pokorny, F. A. and R. C. Smith. 1976. Chemical pruning of azalea stock plants
and subsequent effects on rooting. J. Southern Nurseryman's Assoc. 3:13-20.
5. Shu, L. J. 1979. Comparisons of chemical pinching agents on azaleas
Rhododendron cvs. M. S. Thesis. Auburn University, AL 36849.
6. Shu, L. J. and K. C. Sanderson. 1979. Effects of several chemical pinching
agents applied to azalea cuttings prior to rooting. Proc. SNA Res. Confr.
24:203.
Further Studies on Atrinal on Azalea Plants:
Concentration and Cultivars
Kenneth C. Sanderson and Willis C. Martin, Jr.
Auburn University Agricultural Experiment Station
Nature of Work:
The chemical pinching agent, Atrinal
TM 
or dikegulac sodium (sodium salt of
2,3:4, 5-bis-O-(l-methylethylidene- -L-xylo-2-hexylofuranosonic acid), has been
found to be an effective chemical pinching agent on azaleas (2,3,4,5,6,7,8,9).
Sanderson and Martin (9) have also noted that it improves plant shape and reduces
the number of by-pass shoots at flowering. Delayed plant growth following treat-
ment (2,3,4,7,8), as well as retardation (2,7,9), has raised serious questions
concerning the use of Atrinal
TM 
in the production of azaleas. Researchers have
reported growth delays from 7 weeks (4 to 24 weeks (8). Shu and Sanderson (10)
found that 5 to 6 weeks after Atrinal treatment, shoot length increased normally,
indicating that dikegulac sodium did not have a long term depressive effect on
azalea shoot growth and development. Atrinal's cost and potential retarding effects
may vary with the cultivar and concentration used.
The purpose of the present investigation was to examine the effect of various
concentrations of Atrinal on 5 cultivars of azaleas.
Cuttings of azalea cvs. Alaska, Dorothy Gish, Gloria, Kingfisher, and Red
Wing were propagated on June 26, grown as liners in 65
0
F minimum night temperature
(MNT) greenhouse, sheared to 5 inches in height on January 20, and treated with
Atrinal
TM 
at concentrations of 0.30 per cent, 0.40 per cent, 0.50 per cent and
0.60 per cent on March 22. Both a check (no treatment) and a 4.20 per cent
Off-Shoot-OTM treatment were included for comparison. Approximately 18.3 ml of
spray solution was applied to each plant with a low pressure, high volume sprayer.
A randomized block design consisting of 5 replications, 6 treatments, and 4
('Alaska' and 'Dorothy Gish'), 7 ('Gloria'), or 8 ('Kingfisher' and 'Red Wing')
plants per treatment was used with each cultivar being a separate experiment.
Data on shoot number per plant were collected 8 weeks after treatment.
Results and Discussion:
AtrinalTM-treated plants produced more shoots than check plants on all culti-
vars (Table 1), thus confirming the results of other researchers (2,3,4,5,7,8,9,
10). Apical dominance was rapidly restored on check plants and resulted in new
shoots being initiated near the shearing point, confirming Barrick and Sanderson's
(1) observations on shoot development. Shoots on Atrinal-treated plants were de-
layed and retarded but shoots developed further away from the shearing point
than shoots on check and Off-Shoot-0M-treated plants. Atrinal at 0.50 per cent
seemed to be a satisfactory concentration for maximum shoot number development
on all cultivars except 'Red Wing'. A concentration of 0.60 per cent produced
the maximum number of shoots on 'Red Wing' plants and was statistically different
from lower Atrinal concentration, Off-Shoot-0TM, and the check. 'Kingfisher'
plants produced a comparable number of shoots at all concentrations of Atrina
TM
.
Generall , Off-Shoot-0TM treatments had more shoots than the check, however
AtrinalT 1treated plants at 0.50 per cent and 0.60 per cent usually produced more
shoots than Off-Shoot-OTM-treated plants. This work shows that Atrinal at a con-
centration of 0.50 per cent will produce the maximum number of shoots on most
cultivars.
11
Table 1. Number of new shoots developed on sheared azaleas cvs. 'Alaska',
'Dorothy Gish', 'Gloria', 'Kingfisher', and 'Red Wing' 8 weeks
after treatment with various concentrations of Atrinal.
Cultivars
Treatment Alaska Dorothy Gish Gloria Kingfisher Red Wing
Atrinal 0.30% 36.6 bcz/ 43.1 bc 48.7 b 21.5 a 21.2 b
Atrinal 0.40% 41.8 bc 55.8 ab 49.0 b 25.3 a 22.3 b
Atrinal 0.50% 48.6 a 67.5 a 62.3 a 22.1 a 22.2 b
Atrinal 0.60% 45.0 ab 56.0 ab 63.2 a 25.2 a 25.1 a
Off-Shoot-O0 4.20% 34.4 c 38.1 dc 37.8 c 15.6 b 16.6 c
Check 23.8 d 25.1 d 23.0 d 8.9 c 8.6 d
E-/Mean separation in columns by Duncan's 
multiple range test, 5% level.
Literature Cited:
1. Barrick, W. E. and K. C. Sanderson. 1973.
ture, and node position on vegetative shoot
cv. Rhodendron. J. Amer. Soc. Hort. Sci.
Influence of photoperiod, tempera-
growth of greenhouse azalea,
98(4):331-334.
2. Bocion, P. F., W. H. de Silva, G. A. Huppi and W. Szkrybalo. 1975. Group
of new chemicals with plant growth regulatory activity. Nature 258(5531):
142-144.
3. Breece, J. R., T. Furuta and H. Z. Hield. 1978. Pinching azaleas chemi-
cally. Flower and Nursery Report for Commercial Growers. Calif. Agr. Ext.
Serv. Winter. p. 1-2.
4. Cohen, M. A. 1978. Influence of dikegulac sodium, Off-Shoot-O, 
and manual
pinching on rhododendrons. Sci. Hort. 8:163-167.
5. De Silva, W. H., P. F. Bocion and H. R. Walther, 1976. Chemical pinching
of azalea with dikegulac. HortScience 11(6):569-570.
6. Finger, H.
Gartenwelt
1975. Atrinal, a new chemical pinching agent for azaleas.
75(4): 77-78.
7. Heursel, J. 1975. Results of experiments with dikegulac used on azaleas
(Rhododendron simsii Planch). Med. Fac. Landbouw. Rijksuniversiteit. Gent.
40:849-857.
8. Heursel, J. 1979. Invoed van de groeiregulator dikegulac op de scheut-
vorming, de verkoopdiameter, het bloeitijdstip en de bloemgrootte bij enkele
cultivars van Rhododendron simsii Planch. (Azalea indica L.). Nededekubg
Rijksstation Sierplantenteelt 43 :1-89.
12
9. Sanderson, K. C. and W. C. Martin, Jr. 1977. Effect of dikegulac as a post-
shearing shoot-inducing agent on azaleas, Rhododendron spp. HortScience
12 (4) :337-338.
10. Shu, L. J. and K. C. Sanderson. 1980. Dikegulac sodium influences shoot
growth of greenhouse azaleas, Rhododendron cv. HortScience 
15:286-287.
Chemical Pinching of Garden Chrysanthemums with Off-Shoot-0, Tipnip,
Chemshear, and UBI-P293
Kenneth C. Sanderson and Willis C. Martin, Jr.
Nature of Work:
Chemical pinching of Chrysanthemum X morifolium Ramat has been an objective
of Auburn researchers for more than a decade (4,8). Early work 
considered chemi-
cals that selectively destroyed apicial meristems. The problem restricting wide
use of destructive chemical pinching agents has been the inadequacy 
of the safe
margin between killing the terminal meristem on one hand and causing 
injury to non-
target tissue on the other (6). This problem is less important on garden chrysan-
themums than on florist chrysanthemums because garden chrysanthemums are pinched
more than once and subsequent growth following a pinch would obscure 
damage from
earlier chemical pinching. Some success in pinching garden chrysanthemums 
has
been achieved with non-destructive or metabolic inhibitors 
(9). Recently, three
new chemicals have become available for research purposes. 
Tipnip (n-undecanol
and isomeric alcohol) and Chemshear (dimethyldodecylamine caprylate) affect apical
meristems in the same manner as fatty acids (1,2). UBI-P293 (2,3-dihydro - 5,6 -
diphenyl - 1,4 - oxathiin) is a metabolic inhibitor 
reported to reduce apical
dominance in potted chrysanthemums (3,7) and disbud chrysanthemums (5). 
Visually,
plant tissues are unaffected by UBI-P293 treatment. This paper 
reports on 2 green-
house experiments conducted to evaluate Off-Shoot-O, Tipnip, 
Chemshear, and UBI-
P293 as pinching agents for garden chrysanthemums. Chrysanthemums cvs. Jackpot,
Stardom, Tango, and Yellow Starlet were grown 2 plants per 6-inch pot 
in a soil,
peat, and bark (v/v/v) medium. Rooted cuttings were planted on 
March 20 and pinching
treatments were applied on April 12 in Exp. 1. 
Plants received a 4-hour light
break between 10 p.m. and 2 a.m. from incandescent light bulbs during 
March 20 to
April 11. Black cloth was applied to the plants from 4:30 p.m. to 7:30 
a.m. daily
starting on April 12 and ending when flowers showed color. 
Fertilization con-
sisted of weekly application of 2 lb. per 100 
gallons of 20-20-20 fertilizer.
Pinching treatments were applied to 6 pots (12 plants) 
using approximately 20
ml. of spray per plant with no wash-off. Shoot 
number and plant height above the
pot were determined at flowering.
In Expt. 2, cuttings were potted, as in Expt. 1, on August 10. On August
28, all plants were cut to a 3-inch height. Chemical spray treatments 
were applied
on September 12 and reapplied on September 28. Each cultivar (same 
cultivars as
Expt. 1) was established as a separate experiment. A randomized 
block design
with 4 pots per treatment and 3 replications were used in each experiment. 
Cultural
procedures were similar to Expt. 1. Plants received supplementary 
light in the
middle of the night (10 p.m. to 2 a.m.) from August 10 
to September 27 were suf-
ficient for flower bud initiation and development. Prevailing greenhouse tempera-
tures under a fan and pad cooling system were used during the day. A minimum night
temperature of 62
0
F. was maintained at night.
Data on plant height and total number of flowers per pot (2 plants) was recorded
at flowering.
Results and Discussion:
Expt. 1. Generally more shoots were produced on hand pinched (check), Off-
Shoot-O, and Tipnip treated plants (Table 1). Chemshear treatments reduced shoot
number. Generally, plants receiving chemical pinching agent treatments were taller
14
than hand pinched check plants (Table 2). Plants treated with Chemshear exhibited
chlorosis and irregular flowering. The results for UBI-P293 were erratic. Other
researchers (5,7) have reported that time of application (growth stage) influences
the activity of UBI-P293. Menhenett (7) recommends UBI-P293 be applied 1-4 days
after planting.
Expt. 2.Plants receiving hand pinching (check), 2.0% Off-Shoot-O, 0.75% Tip-
nip and 0.3% Chemshear produced the most flowers on 'Jackpot' plants (Table 3).
On 'Stardom' plants, hand pinching, 2.0% Off-Shoot-O, 
1.25% Tipnip, 0.75% Tipnip,
0.6% Chemshear and 0.3% Chemshear treatments produced the most flowers. Hand pinched
and 0.75% Tipnip plants had the most flowers on 'Tango' plants. 'Yellow Starlet'
plants had the most flowers when hand pinched or treated with 2.0% Off-Shoot-O,
1.25% Tipnip, 0.75% Tipnip and 0.3% Chemshear. Generally, UBI-P293 treatments
produced the fewest flowers for all cultivars. Pinching treatments had no effect
on the height of 'Yellow Starlet' plants (Table 4).
UBI-P293 reduced height in the other cultivars. Tallest 'Jackpot' plant
received either hand pinching, 0.6% Chemshear or 0.3% Chemshear. 'Stardom' plants
hand pinched or sprayed with 2.0% Off-Shoot-O, 1.25% Tipnip, 0.75% Tipnip, 0.6%
Chemshear or 0.3% Chemshear were the tallest plants. Treatments of 2.0% Off-
Shoot-0, 1.25% Tipnip, 0.75% Tipnip, 0.6% Chemshear and 0.3% Chemshear produced
the tallest 'Tango' plants.
Both Off-Shoot-O and Tipnip treatments yielded results comparable to hand
pinching in this study. Chemshear caused phytotoxicity while successfully pinching
plants. Large scale testing and commercial experimentation is warranted on Off-
Shoot-O and Tipnip. Special attention should be given to phytotoxicity, margin
of safety, amount of damage, and environmental facotrs.
15
Table 1. Effect of Chemical Pinching Agents on Shoot Number of
Garden Chrysanthemums
Cultivar
Treatment Jackpot Stardom Tango Yellow Starlet Mean
Check 4.7 7.0 4.6 5.8 5.5
2% Off-Shoot-O 2.8 10.3 5.9 3.5 5.6
0.75% Tipnip 4.5 8.8 4.4 3.6 5.3
1.25% Tipnip 5.7 6.9 3.7 3.4 4.9
0.25% UBI-P293 2.3 1.8 4.6 2.0 2.7
1.0% UBI-P293 5.7 3.7 2.8 3.0 3.8
0.125% Chemshear 1.1 3.6 3.1 1.4 2.3
0.25% Chemshear 1.4 2.1 3.3 1.8 2.2
Table 2. Effect of Chemical Pinching Agents on the Height (cm) of
Garden Chrysanthemums
Cultivar
Treatment Jackpot Stardom Tango Yellow Starlet Mean
Check 23.8 20.8 36.0 35.1 29.0
2% Off-Shoot-0 28.3 27.5 41.2 38.2 33.8
0.75% Tipnip 26.3 28.6 37.6 39.6 33.0
1.25% Tipnip 22.3 23.7 35.0 33.9 28.7
0.25% UBI-P293 25.8 27.0 33.2 39.9 31.5
1.0% UBI-P293 22.4 23.2 31.4 33.0 27.5
0.125% Chemshear 28.8 21.3 32.9 42.2 31.4
0.25% Chemshear 25.6 21.1 35.0 39.7 30.4
16
Table 3. Effect of Chemical Pinching Agents on the Total Flower
Number of Four Garden Chrysanthemum Cultivars
Cultivar total flower number
Treatmentz Jackpot Stardom Tango Yellow Starlet
Check 78 aY 110 a
Y  
117 ay 139 a
2.0% Off-Shoot-O 74 ab 105 a 104 b 148 a
1.25% Tipnip 67 bc 98 ab 95 bc 134 
ab
0.75% Tipnip 78 a 110 a 121 a 147 a
1.0% UBI-P293 55 d 80 b 86 cd 95 d
0.5% UBI-P293 48 d 84 b 82 d 103 
dc
0.6% Chemshear 64 c 93 ab 86 cd 117 bc
0.3% Chemshear 71 abc 103 a 100 b 137 a
ZPlants were cut to a 3-inch height on August 28 and received pinching
treatments on September 12 and September 28.
YMeans in columns followed by the same letter(s) are not significantly
different at the 5% level, Duncan's multiple range test.
Table 4. Effect of Chemical Pinching Agents on the Height of Four
Garden Chrysanthemum Cultivars
Cultivar Height (cm)
Treatmentz Jackpot Stardom Tango Yellow 
Starlet
Check 33.5 abY 27.8 a 32.1 bcY 32.0 
aY
2.0% Off-Shoot-0 29.0 cd 28.3 a 36.5 a 
32.8 a
1.25% Tipnip 31.1 bc 27.3 ab 33.4 abc 33.1 
a
0.75% Tipnip 31.3 bc 26.7 abc 33.6 abc 
32.9 a
1.0% UBI-P293 26.8 d 24.0 c 31.3 c 
32.1 a
0.5% UBI-P293 27.5 cd 24.8 bc 30.8 c 
30.6 a
0.6% Chemshear 33.7 ab 27.8 a 33.1 abc 
31.4 a
0.3% Chemshear 37.3 a 29.7 a 36.0 ab 
34.7 a
ZPlants were cut to a 3-inch height on August 28 and received 
pinching
treatments on September 12 and September 28.
YMeans in columns followed by the same letter(s) are not significantly
different at the 5% level, Duncan's multiple range test.
17
Literature Cited:
1. Anon. 1975. Chemshear, an experimental product for chemically pinching
plants. Bul. 75-18. Armak Industrial Chemicals Division, Chicago, IL
60690.
2. . 1975. Tipnip, an experimental product for chemically pinching chrysan-
themums. Bul. 75-19. Armak Industrial Chemicals Division, Chicago, IL.
60690.
3. . 1975. UBI-P293. Plant growth regulant 
for floricultural or ornamental
crops. Technical Form No. AG-116. Uniroyal Chemical 
Division of Uniroyal, Inc.
Bethany, CT.
4. Cathey, H. M. 1968. Report of cooperative trial on chemical pruning of
chrysanthemums with fatty acid eaters. Florists' Rev. 141(3663):19-21, 
87-90.
5. . 1976. Influence of a substituted oxathiin, 
a localized growth
inhibitor, on the stem elongation, branching and flowering 
of Chrysanthemum
morifolium Ramat. J. Amer. Soc. Hort. Sci. 101:599-604.
6. Gogue, G. J. and H. P. Rasmussen. 1974. Stem girdling of 
chrysanthemum
cultivars by chemical pinching agents. J. Amer. Soc. Hort. Sci. 
99:292-297.
7. Menhenett, R. 1978. Chemical pinching of pot chrysanthemums 
with 2,3-dihydro-
5,6- diphenyl-l,4-oxathiin. Sci. Hort. 8:81-89.
8. Sanderson, K. C. and W. C. Martin, Jr. 1969. Chemical 
pinching saves time and
labor. Highlights Ag. Res. Auburn Univ. (Ala.) Agr. xp. Sta. 
16(1)
9. and . 1974. Effects of DPX 
1846, PBA and glyphosine on
shoot growth in garden chrysanthemums. Proc. Florida 
State Hort. Sci. 87:558-560.

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