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CFREC-A Foliage Plant Research Note RH-91-10
R.W. Henley, A.R. Chase and L.S. Osborne University of Florida, IFAS Central Florida Research and Education Center - Apopka 2807 Binion Road, Apopka, FL 32703-8504
Reference Pest Control Guides Here
CHAMAEDOREA PALM
The term, chamaedorea palms, is used in this publication as a collective common name for those species of palm which belong to the genus - Chamaedorea. Although there are over 100 species of Chamaedorea, only a half dozen or so are produced in commercial quantities for the indoor plant market. Most "chamaedoreas" are natives of the rain forests of Mexico and Central America. Chamaedorea palms have very narrow stems, usually less than 1 inch in diameter, and can be either single-stemmed or multi-trunked, depending upon the species. The leaves are dark green and compound with pinnae (leaflets) arranged along the rachis (midvein) resembling a feather.
CHAMAEDOREA SPECIES GROWN AND ACCLIMATIZED IN FLORIDA
Chamaedorea cataractarum
This species, which has not acquired a widely accepted common name, was introduced to the interior plant industry during the late 1970's and has since lost most of its appeal as an indoor plant since. This low growing plant develops to a height of 24 inches and produces basal shoots with age. Its foliage is dark green and distinctly glossy. Its slow growth and extreme susceptibility to spider mites, especially indoors, has eliminated it from the list of good palms to use indoors. Chamaedorea cataractarum is still grown on a limited scale for a landscape palm in south Florida.
Chamaedorea elegans (Parlor Palm)
The parlor palm has also been listed as Collinia elegans and, invalidly, as Neanthe bella. This single- stemmed species is native to Mexico and Guatemala where it grows to a height of 5 to 6 feet. It is grown widely in central Florida, primarily in greenhouses, and, to a lesser extent, in south Florida under shadehouses. Plants are available in cavity tray plugs 1 inch in diameter and larger and in pots ranging from 2 to 14-inches across. The small sizes are used for dish gardens and liners, the intermediate sizes for retail markets and most of the 10 to 17-inch pots are used by commercial interiorscapers. In all cases sufficient plants are used per container to produce a "full" plant.
Chamaedorea erumpens (Bamboo Palm)
Native to Guatemala and Honduras, the bamboo palm is an upright plant which produces medium green leaves with relatively broad pinnae. Along with C. `Florida Hybrid' and C. seifrizii, C. erumpens produces several basal shoots with age, when the light intensity is adequate, which increases the plant density and spread. Since bamboo palm and the other two species mentioned do not achieve their true character till they reach about 3 to 4 feet in height, the are rarely sold in pot diameters less than 10 inches.
Chamaedorea `Florida Hybrid' (Florida Hybrid Bamboo Palm)
The Florida Hybrid bamboo palm is a cross between C. erumpens and C. seifrizii that occurs naturally in parts of south Florida. Pinnae of Florida Hybrid are intermediate in width between those of the two parents, except the terminal ones which are broad. Florida Hybrid is produced in much larger numbers than C. erumpens, but not as abundantly as C. seifrizii.
Chamaedorea radicalis (Radicalis Palm)
The radicalis palm was recently introduced to the interiorscape industry in some quantity, primarily by one Florida nurseryman. The plant is indigenous to rather high elevations of northern Mexico and is among the most cold tolerant Chamaedorea species ever grown in Florida. It is a single-stemmed species with leaves which resemble the areca palm. The color of radicalis palm foliage is medium to dark green with a grayish cast. Several seedlings must be used per container to produce full plants. Although this plant is still being evaluated by some interiorscapers, results thus far look good under medium and low light levels indoors.
Chamaedorea seifrizii (Reed Palm)
This species is presently the most popular of the prominently columnar chamaedorea palms used indoors. The pinnae (leaflets) are distinctly narrower than the bamboo palm and are medium to dark green with a grayish cast. This species displaced the bamboo palm about 15 years ago as the most widely grown columnar species of Chamaedorea, primarily due to its greater resistance to the fungal infection caused by Gliocladium.
Other chamaedorea palms, such as C. costaricana, C. metalica, C. microspadix and C. tepejilote have been tested by palm specialists for their commercial value with limited success. As plant evaluation work continues, additional species may emerge as reliable and useful plants for interior use.
PRODUCTION
Growers have two options as they begin production of chamaedorea palms, purchase and germinate seeds or purchase liners from a propagator. Those choosing to use seeds must first be concerned with the viability of purchased seed and then understand how to handle seed after it is received. Most chamaedorea palm seed is still collected from tropical and semi-tropical habitats in the fall and then sold through seedsmen, as quickly as possible, to commercial nurserymen.
Seed cleaning is rarely necessary with chamaedorea seeds which have a rather thin fleshy outer layer. Seeds can be sown in propagation beds (raised or ground level), community trays (flats) or cell trays. The trend is toward production of plugs by sowing several seeds per cell tray cavity and covering them with about 1/4 inch of medium. Seed germination and seedling growth is excellent in variety of the well drained peatlite mixes adjusted to a pH range of 5.5 to 7.0.
Although it is desirable have seeds throughout the year so several crops can be staged, seed viability decreases as the storage period increases. Some nurseries hold seed as late as early to mid-spring with viability losses of about 10 percent per month or more per month.
Another option available to nurserymen is to sow the seed at the time it is received , usually mid-fall, and accelerate germination of a portion of the crop by warming the medium to 90°F for several weeks until germination occurs. Every month or two additional lots of the sown seed can be brought in from a holding area where temperatures may be allowed to drop into the low 40's. This strategy will permit production of crops of several stages each year.
Since light is not needed for germination, special chambers or rooms can be built to accommodate closely spaced layers of trays for several weeks at a time. One to two inches between trays is sufficient for circulation of warm air within the chamber. In some cases trays con be stacked one upon the other in a staggered configuration which permits some air movement and heat transfer through the stack. Although germination is never uniform with a seed lot, trays should be removed from dark germination chambers after approximately 25 percent of the viable seeds have sprouted.
Production of chamaedorea palms often includes several months in full sun to encourage basal shoot production and good stem diameter, but most species develop their best color in shade, except C. cataractarum, which maintains good color even when grown in full sun. Chamaedorea elegans grows best in shaded conditions from the seedling stage to the point of finishing. Suggested light intensity ranges for production of acclimatized chamaedoreas are presented in Table 1.
Table 1: Suggested light intensity ranges, fertilizer rates and structures for production of acclimatized chamaedorea palms.
Light Fabric Fertilizer
intensity shade (lb actual Best
Species (foot candles) (% shade) N/1000 SF/mo)z structure x
C. elegans 1500-3000 70-80 2.9 G
C. erumpens 3000-6000 40-70 3.4 S
C. `Florida Hybrid' 3000-6000 40-70 3.4 S
C. radicalis 3000-6000 40-70 3.4 S
x Use a 3-1-2 or 2-1-2 ratio fertilizer.
z G = Greenhouse and S = shadehouse.
PHYSIOLOGICAL PROBLEMS
1) Chilling induced growth inhibition
Symptoms - Little to no seed germination or plant growth and chlorosis, particularly of the lower foliage.
Control - The medium should be maintained at 90°F for the most rapid even germination; below this, germination slows and disease problems increase. However, this temperature will retard root growth and should be reduced to 80°F once peak germination has occurred. Most root growth of palms stops at 60-65°F and root activity slows so that uptake of nutrients is reduced. This reduction in uptake may not be uniform and some micronutrient deficiencies may occur in colder weather.
2) pH induced nutrient deficiencies
Symptoms - High medium pH can induce deficiencies of manganese and iron may cause interveinal chlorosis of young foliage. As deficiencies become more severe, necrotic spots will appear within the chlorotic tissue.
Control - Maintaining soil pH below 7 will improve the availability of iron and manganese and slow the leaching of magnesium. Application of the appropriate nutrient will correct a problem, but palm response tends to be slow. Foliar sprays will hasten color improvement compared to soil application, but use low rates of application rates to avoid phytotoxicity from the sprayed materials.
3) Root damage and foliar tip burn
Symptoms - Poor or dead roots with burned leaf tips and/or margins.
Control - Chamaedoreas are sensitive to waterlogged or poorly aerated soils, and the slow reaction time of palms means that much root damage can occur before foliar symptoms are observed. The potting medium must be free-draining. Excess soluble salts, 1000 ppm or more, will damage roots. Leaf tip and margin burn usually occurs relatively soon after root damage begins. Leaching will remove excess salts, but the pots must be drained well when this is completed.
4) Magnesium deficiency
Symptoms - Chlorosis of lower leaves initially, with symptoms developing at the margin of the leaf (tips of the leaflets) and progressing inward. This is a rather common deficiency since the chamaedoreas are a long term crop and magnesium is not included in many fertilizer formulations.
Control - Use dolomitic limestone for liming material in formulation of peatlite mixes. Supplement fertilizer program with readily soluble and affordable form of magnesium. Magnesium sulfate is frequently used for that purpose.
5) Fluoride toxicity
Symptoms - Frequently a dark brown tip necrosis.
Control - Avoid known sources of fluoride, particularly superphosphate used by some potting media formulators to supply phosphorus for plant growth. Chamaedoreas are moderately sensitive to the presence of fluoride in the potting medium solution. When minimal amounts of fluoride are present in the medium solution, damage to the plant can usually be prevented by maintaining the medium pH between 6.0 and 7.0.
6) Copper toxicity
Symptoms - Brown, elliptical spots on the pinnae (leaflets) which slightly resembles a fungal leaf spot.
Control - Avoid use of fungicides containing copper on small palms. The concentration of copper used in blended micronutrient fertilizers is not considered a potential problem if used at recommended rates.
7) White seedlings
Symptoms - Seedlings emerge white and die later as they become larger. If this condition is observed, it involves only a small percentage of the crop.
Control - The white seedlings are albino plants which lack the chlorophyll needed to produce their own food. The albino seedlings usually develop several leaves before the food reserve in the seed. Since albinism is controlled plant genetics, there is no control other than selection of seed source is known.
Reference Pest Control Guides Here
FUNGAL PROBLEMS
1) Gliocladium stem blight - (Gliocladium vermosceni)
Symptoms - This disease is characterized by yellowing of basal fronds, black stem lesions with a gummy exudate, and masses of pink-orange conidia of the fungus covering necrotic tissues. Fronds quickly die when severely infected and their removal results in a thin plant with decreased salability.
Control - Disease appears to be most severe during the winter months. When manicuring these palms in the nursery, fronds should be removed only after they are completely brown, since removal of green fronds leaves wounds exposed which facilitates the entrance of the fungal conidia. Pruning and sanitation should be followed by a fungicide application to protect any open wounds from infection. Most species of Chamaedorea appear to be susceptible to Gliocladium as well as many other palms used in landscapes.
2) Helminthosporium leaf spot - (Bipolaris setariae and Exserohilum rostratum)
Symptoms - Lesions are usually 1/8 to 1/4" long, reddish brown to black and found all over the frond surface. A yellow halo (margin) frequently surrounds the lesions. Under optimum conditions, the lesions coalesce and form large irregularly shaped necrotic areas on leaf tips and margins.
Control - Elimination of foliar wetting will eliminate disease.
3) Phytophthora root and stem rot - (Phytophthora sp.)
Symptoms - Phytophthora root and stem rot occurs mostly during the summer months and is typified by severe loss of roots and wilting of the tops. Roots are blackened and their cortex is easily removed from the central core. The symptoms on the upper portions may be confined to loss of stems starting with lesions hear the soil line and yellowing of leaves on these stems, or can include discrete lesions on the stems. Lesions are black and sunken, and can appear on portions as high above the soil as 12 inches.
Control - Use of pathogen-free potting medium, pots, and seedlings is essential. The soil moisture should be maintained as low as possible to reduce pathogen growth.
4) Root rots and damping-off (many fungi)
Symptoms - Poor germination, blackening of roots, or mushiness followed by yellowing, wilting and loss of the plant or seedling. Fusarium, Rhizoctonia, Pythium, Phytophthora spp. each cause these symptoms.
Control - Same as for Phytophthora stem and root rot.
Reference Pest Control Guides Here
INSECT AND RELATED PROBLEMS
The major arthropod pests of this plant group are mites. However, there are a number of insect, such as scales, seed feeding ambrosia beetles, thrips, and fungus gnats which also attack palms. In the control section for each pest, a few of the many registered and effective pesticides will be listed. For a complete listing, please consult the references at the end of this report.
1) Fungus gnats
Symptoms - Fungus gnats are small black flies (1/8 inch long) and are frequently observed running around the soil surface or on leaves and are often confused for Shore flies (see later section). The adults have long bead-like antennae and their legs hang down as they fly. These insects are very weak fliers and appear to "flit" around randomly. The larvae are small legless "worms" with black heads and clear bodies that inhabit the soil. The larvae spin webs on the soil surface which resemble spider webs. Damage is caused by larvae feeding on roots, root hairs, leaves in contact with the soil and lower stem tissues. Feeding damage may predispose plants to disease and they are often found in close association with diseased plants or cuttings. Adults do not cause any direct damage, but are responsible for many consumer complaints to growers. Adults emerge and fly around in retail shops, homes, or offices and are therefore a nuisance. For further information please consult Extension Entomology Report #74 (Management of fungus gnats in greenhouse ornamentals).
Control - Reduce the amount of water applied to each pot where possible. Avoid algae growth where possible. Soil drenches or soil-surface sprays are effective at controlling the larvae. Nematodes that seek out insects in the soil are sold commercially and have been shown to control these pests without causing any negative effects to the host plants. Adults are very sensitive to most chemicals.
2) Mites (Tarsonemid)
Symptoms - Mites are very small and go unnoticed until plants become severely damaged. A tarsonemid mite (Steneotarsonemus furcatus DeLeon) which is related to the broad mite can cause severe damage to C. elegans. Plants infested with mites begin to turn yellow or become speckled. Speckling, in the case of this tarsonemid mite, is much more distinct than damage caused by spider mites.
Control - The critical point in any control program is thorough coverage with the pesticide. The best control program is to minimize the possibility of introducing mites into the growing area on infested plant materials. In the case of this tarsonemid mite, it would help to grow palms as far away from the preferred hosts of this mite (Maranta sp., Calathea sp., and Bermuda grass) as possible.
3) Mites (Two-spotted spider mite)
Symptoms - Two-spotted spider mites are very small and go unnoticed until plants become severely damaged. Damaged foliage begins to turn yellow or become speckled due to the feeding of mites. Webbing, loss of leaves and plant death can occur when mite populations reach high levels. Often the presence of this pest is overlooked because the cast skins and webbing produced by this mite are confused for dust on undersides of leaves. Mites have round pale yellow to reddish eggs deposited on the under surfaces of leaves; nymphs and adults have two dark patches on either side of there bodies.
Control - The critical point in any control program is thorough coverage with the pesticide. The best control program is to minimize the possibility of introducing mites into the growing area on infested plant material. Biological control programs have worked in small scale studies but remain unproven in commercial greenhouses.
4) Scales
Symptoms - Infested plants become weakened or stunted and begin to die. Scales can be found feeding on leaves, petioles, or stems. They are usually distinct from the plant material on which they are feeding. Their shape (round to oval), size (pinpoint to 2 mm long), and color (light to dark brown) are quite variable and many scales are hard to distinguish from the plant material on which they are feeding.
Control - Systemic materials are preferred. Control of root mealybugs is accomplished with soil drenches with an insecticide. When pesticides are applied to the soil, care must be taken to assure that the pots have good drainage and that no saucers are attached, or phytotoxicity may result.
5) Shore flies
Symptoms - Shore flies small black flies (1/8 inch long) and are frequently observed sitting on the tips of leaves or on the soil surface feeding on algae. The adults have very short antennae. These insects very strong fliers and exhibit directed flight (straight between 2 points). The larvae inhabit the soil and are small legless "worms" with clear bodies and no obvious heads. No known damage is caused by larvae. This insect is believed to feed only on algae. Adults do not cause any direct damage, but may be responsible for spreading plant pathogens, reducing value by defecating on the leaves (small black to green spots) and for many consumer complaints to growers. Adults emerge and fly around in retail shops, homes, or offices and are therefore a nuisance.
Control - Reduce the amount of water applied to each pot where possible. Avoid algae growth on walkways, benches, and cooling pads. Chemicals are not believed to be very effective in the control of this pest.
6) Thrips (Western Flower Thrips and Banded greenhouse thrips)
Symptoms - Thrips are small (less than 1/20), thin insects. Adult thrips can be identified by a long fringe of hair around the margins of both pairs of wings. Color varies between species with western and other flower thrips being yellow to light brown and banded greenhouse thrips and a few other thrips that feed mainly on leaves being dark brown to black. Feeding takes place with rasping type mouth parts. Infested leaves become curled or distorted, with silver-gray scars or calloused areas where feeding has occurred. Thrips can transmit the tomato spotted wilt virus to many different ornamentals. Any unusual symptoms should be investigated.
Control - Many materials are registered and effective at controlling thrips.
7) Beetles
Symptoms - Seeds have small circular holes from which the small darkly colored adult beetles have emerged. This problem should be detected before the seeds are planted, otherwise significant losses due to poor germination will result. When a container of heavily infested seed is first opened, beetles will often be observed.
Control - Use clean seed.
Pesticides should be applied according to label
directions.
Regardless of the pesticide or mixture of
pesticides used, it is
strongly recommended that the effects be evaluated on a few
plants, under your particular conditions before treating all
plants.
Mention of a commercial or proprietary product
in this paper
does not constitute a recommendation by the authors,
nor does it imply registration under FIFRA as amended.
Reference Pest Control Guides Here
REFERENCES
1. Bailey, L.H. 1976. Hortus Third. Macmillan Publishing Company, Inc. New York, NY. 1290 pp.
2. Chase, A.R. 1990. Phytotoxicity bactericides and fungicides on some ornamentals. Nursery Digest 24(5):11.13 pp.
3. Chase, A.R. and R.T. Poole. 1986. Troubleshooting guide to foliage. Greenhouse Grower 4:(11) 24-25, 27.
4. Conover, C.A. and R.T. Poole. 1990. Light and fertilizer recommendations for production of acclimatized potted foliage plants. CFREC-A Research Report RH-90-1.
5. McConnell, Dennis B., Richard W. Henley and Cathrine B. Kelly. 1989. Commercial foliage plants: twenty years of change. Proc. Fla. Hort. Soc. 102:297-303.
6. Poole, R.T. 1975. Parlor palm seed germination. Florida Foliage Grower 12(8):1-
7. Price, J., D.E. Short and L.S. Osborne. 1989. Management of fungus gnats in greenhouse ornamentals. Extension Entomology Report #74.
8. Short, D.E., L.S. Osborne and R.W. Henley. 1984. Phytotoxicity of insecticides and miticides to foliage and woody ornamental plants. Extension Entomology Report #57.
9. Short, D.E., L.S. Osborne and R.W. Henley. 1991. 1991-1992 Insect and related arthropod management guide for commercial foliage plants in Florida. Extension Entomology Report #52. 13 pp.
10. Short, D.E., J. Price and L.S. Osborne. 1989. Sweetpotato whitefly on ornamental plants. Extension Entomology Report #73.
11. Simone, G.W. and A.R. Chase. 1989. Disease control pesticides for foliage production (Revision #4). Plant Protection Pointer. Extension Plant Pathology Report #30. [also in Foliage Digest 12(9)1-11].