Title: TropicLine
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 Material Information
Title: TropicLine
Series Title: TropicLine
Physical Description: Serial
Creator: Fort Lauderdale Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida
Publisher: Fort Lauderdale Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida
Place of Publication: Ft. Lauderdale, Fla.
Publication Date: November/December 1992
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Bibliographic ID: UF00089450
Volume ID: VID00003
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.

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TropicLine vol. 5, no. 5


Trop i cLin e Volume 5, Number 5, November-December, 1992


Editor: Alan W. Meerow
Christine T. Stephens, Dean, Cooperative Extension


Copper Hydroxide Controls Root Circling In

Container-Grown West Indies Mahogany and

Carpentaria Palm

Sven E. Svenson

Former Floricultural Physiologist

and

Timothy K. Broschat

Tropical Ornamental Horticulturist

Circling and deflected roots have always been a problem for the container nursery industry. Matted, kinked,
and otherwise deformed roots of container-grown stock has been associated with increased mortality, poor
mechanical stability, and susceptibility to drought after transplanting (Nichols and Alm, 1983). Root pruning
before transplanting container-grown plants may eliminate root system deformation, but may also reduce
survival and growth (Geisler and Ferree, 1984; Larson, 1980). The application of copper compounds to
interior container wall surfaces prevents root growth at the container-medium interface, and may increase
root growth after transplanting (Arnold and Struve, 1989; Wenny et al., 1988). Response to copper-treated
containers differs among various ornamental species (Beeson and Newton, 1992). Copper treatment has
helped suppress root circling in flats (Nussbaum, 1969) and tree seedling tubes (Burdett, 1978; Struve et al.,
1987), but routine use of copper-treated liners for production of ornamental species has received less study.

The objective of this study was to determine if Cu(OH)2 applied to all interior container surfaces could
control circling root growth of two landscape tree species commonly produced in containers for planting in
south Florida landscapes.

Materials and Methods

West Indies Mahogany. Mahogany seed was collected in southwestern Broward County in May of 1991.
Seeds were sown on 2 July 1991 in 0.5 liter (9 cm top diameter) pots filled with 0.4 liters of a pine
bark:Florida peat:sand (5:4:1 by volume) medium. After 30 days, seedlings were transplanted into 2.4 liter
(15.2 cm top diameter) containers filled with 2.25 liters of the same soilless medium. A dibble application of
24 g Osmocote 17N-3P-9.9K (12 to 14 month formula; Grace/Sierra, Milpitas, CA) was applied at potting.
Before planting, interior container surfaces were treated as follows: 1) untreated; 2) painted with white
acrylic latex paint; 3) sprayed with a solution containing 30 ml NuFilm-17TM surfactant per liter of solution
(96% di-1-p-Menthene; Miller Chemical and Fertilizer Corporation, Hanover, PA); 4) painted with white
acrylic latex paint containing 100 g of Cu(OH)2 per liter of paint, obtained by mixing KocideTM 101 WP


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(Griffin Corporation, Valdosta, GA) with paint; 5) sprayed with a solution containing 30 ml NuFilm-17 and
100 g of Cu(OH)2 per liter of solution. Seedlings were grown under full sun (1800 umol m-2 s-1 at solar
noon averaged throughout the study), using daily overhead irrigation. A completely randomized experimental
design was used.

Plants were harvested on 6 December 1991 by separating the plant into shoot, root, and circling root sections,
and dry weights were recorded after drying the sections at 65oC for two days. Data were analyzed for
significant response to Cu(OH)2 using analysis of variance, and mean comparisons were made using
Duncan's New Multiple Range Test.

Carpentaria Palm. Carpentaria palm seed was collected in southwestern Broward County in March 1991 and
sown in germination flats. On 9 August 1991, seedlings were transplanted into 0.5 liter (9 cm top diameter)
pots filled with 0.4 liters of the same growing medium described above. A dibble application of 6 g of
OsmocoteTM 17N-3P-9.9K (12-14 month formula) was applied at transplanting, and a top-dress application
of the same amount was applied on 2 March 1992. Seedlings were grown under 63% black-poly shade cloth.
Plants were harvested on 2 April 1992. Design, harvest and data analysis were the same as described for
mahogany.

Results

Dry weights of whole plants or of whole root systems of mahogany were not influenced by any interior
container surface treatments (Table 1). Without Cu(OH)2, circling roots comprised 16 to 18% of mahogany
root systems, increasing to 25% for the NuFilm-17 treatment. Cu(OH)2 applied with paint or NuFilm-17 as a
carrier almost eliminated circling root growth, reducing circling root dry weight to less than 1% of the
mahogany root system.

Showing a response similar to mahogany, dry weights of whole plants or of whole root systems of
carpentaria palm were not influenced by any interior container surface treatments (Table 2). Unlike
mahoganies, circling roots comprised approximately 50% of the palm root system without Cu(OH)2, and
there was no response to the NuFilm-17 application. Cu(OH)2 applied with paint or NuFilm-17 as a carrier
reduced circling root growth to less than 15% of the palm root system. The coarse roots of carpentaria palm
appear to be less sensitive to the 100 g Cu(OH)2 treatment.

Discussion

Copper containing compounds mixed with white acrylic latex paint and applied to interior container surfaces
have been shown to control root growth at the container-medium interface, and to increase root density
(Arnold and Struve, 1989; Burdett, 1978; Struve et al., 1987). The 97 to 99% reduction and 85 to 90%
reduction of circling root dry weight for mahogany and carpentaria palm, respectively, when either paint or
NuFilm-17 was used as the carrier has shown that paint is not a required carrier when copper compounds are
used to control root development. Application of Cu(OH)2 in paint produced an unsightly container, while
application of Cu(OH)2 in NuFilm-17 was not readily visible.

If the percentage of circling roots is considered as an indicator of the degree of root system deformation, then
carpentaria palm roots appear to be more sensitive to root deformation when grown in containers compared
to container-grown mahogany. The growth habit of the natural root system of a species may be critical to the
degree of root growth control that can be obtained using Cu(OH)2.

For both mahogany and palm, application of Cu(OH)2 to interior container surfaces reduced circling root
growth without reducing the growth of the whole root system. Beeson and Newton (1992) reported similar


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results for mahogany and windmill palm (Trachycarpusfortunei). Roots were forced to grow within the
growing medium rather than along the container-medium interface. The increased root growth within the
growing medium could provide increased root surface contact with the water and mineral elements stored in
the growing medium, possibly supporting faster growth from the limited soil volume within the container.
Beeson and Newton (1992) recorded faster height growth rates for mahogany grown in Cu(OH)2 treated
containers.

The use of Cu(OH)2 treated containers when growing mahogany eliminates the need to prune roots of
container-grown stock before transplanting, and may support faster growth and establishment with less
mortality after transplanting (Arnold and Young, 1991). Unlike the dicotyledonous mahogany, reducing
circling of the adventitious root system of the monocotyledonous carpentaria palm may be less important to
establishment after transplanting (Broschat and Donselman, 1990; Meerow and Begeman, 1991). Use of
Copper-treated containers may not produce the beneficial growth after transplanting palms that has been
reported for other species (Arnold and Young, 1991).

Literature Cited

Arnold, M.A. and D.K. Struve. 1989. Growing green ash and red oak in CuCO3-treated containers increases
root regeneration and shoot growth following transplant. J. Amer. Soc. Hort. Sci. 114:402-406.

Arnold, M.A. and E. Young. 1991. CuCO3-painted containers and root pruning affect apple and green ash
root growth and cytokinin levels. HortScience 26(3):242-244.

Beeson, R.C. and R. Newton. 1992. Shoot and root responses of 18 southeastern woody ornamentals to
copper hydroxide-treated containers. J. Environ. Hort. (In Press).

Broschat, T.K. and H.M. Donselman. 1990. Regenertion of severed roots in Washingtonia robusta and
Phoenix reclinata. Principes 34:96-97.

Burdett, A.N. 1978. Control of root morphogenesis for improved mechanical stability in container-grown
lodgepole pine. Can. J. For. Res. 8:483-486.

Geisler, D. and D.C. Ferree. 1984. Response of plants to root pruning. Hort. Rev. 6:155-188.

Larson, M.M. 1980. Effects of atmospheric humidity and zonal soil water stress on initial growth of planted
northern red oak seedlings. Can. J. For. Res. 10(4):549-554.

Meerow, A.W. and J.P. Begeman. 1991. Observations on palms produced in grow bags. Proc. Fla. State Hort.
Soc. 104:367-368.

Nichols, T.J. and A.A. Alm. 1983. Root development of container-reared, nursery-grown, and naturally
regenerated pine seedlings. Can. J. For. Res. 13(2):239-245.

Nussbaum, J.J. 1969. Chemical pinching for roots of container plants. Calif. Agric. 23: 16-18.

Struve, D.K., M. Arnold, and D. Chinery. 1987. Red oak whip production in containers. Proc. Intern. Plant
Prop. Soc. 34: 415-420.

Wenny, D.L., Y. Lui, R.K. Dumroese and H.L. Osborne. 1988. First year field growth of chemically root
pruned containerized seedlings. New Forest. 2: 111-118.


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Table 1. Dry weight of whole plant, root system, circling roots, and percentage of circling roots of Swietenia
mahagoni grown in 2.4 liter containers for 4-months after transplanting from 0.5 liter pots. Containers were
treated with copper-hydroxide [Cu(OH)2] in paint or NuFilm-17, with paint or Nufilm-17 only, or were
untreated.


Conaie Te \\Whole Plant dr
\\ eiriht (luraims


Root S\ stem Dr\
\\ ei ht (uIramsi


Circlinu Root Dr\
\\ eiuht (Il ,U ms


o of Circlin
Roots'


Untreated (Control) 26.7 ay


Paint only
NuFilm-17 only
Cu(OH)2 in paint
Cu(OH)2 in
Nufilm-17


26.1 a
24.2 a
23.5 a

27.1 a


S.97 a
c.46 a
0.04 a
'.66 a

S.70 a


1.46 b
1.86 ab
2.26 a
0.04 c

0.04 c


16.4 b
18.7 b
25.3 a
0.4 c

0.5 c


ZAnalysis performed on arcsine transformed data.

YMeans within columns followed by the same letter are not different.

(P<0.05) according to Duncan's New Multiple Range Test; n = 5.

For comparison, 28.35 grams = one ounce.


Table 2. Dry weight of whole plant, root system, circling roots, and percentage of circling roots of
Carpentaria acuminata grown in 0.5 liter containers for 8-months after transplanting from germination flats.
Containers were treated with copper-hydroxide [Cu(OH)2] in paint or NuFilm-17, with paint or Nufilm-17
only, or were untreated.


Container Treattment


\\hole Plant drl
e\\eiult uri,1s)


Root S\ stem Dr\
\\ eiuht IriIms)


Circlinu Root Dr\
\\ eiuht IUms)


')o of Circlin
Roots'"


Untreated (Control) 4.35 ay


Paint only
NuFilm-17 only
CuI)OH' in paint
C(iiu H) in
Nufilm-l"


4.92 a
4.61 a
3 t4 a

4 lor a


1.50 a
1.52 a
1.52 a
1 11 a

1 l2 1


0.85 a
0.73 a
0.81 a
( 12 b


52.4 a
47.3 a
50.2 a
1 5b

14 i b


ZAnalysis performed on arcsine transformed data.

YMeans within columns followed by the same letter are not different.


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(P<0.05) according to Duncan's New Multiple Range Test; n = 10.

For comparison, 28.35 grams = one ounce.


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