Cordyline - Ti Plant

CFREC-A Foliage Plant Research Note RH-91-34

R.W. Henley, L.S. Osborne and A.R. Chase University of Florida, IFAS Central Florida Research and Education Center - Apopka 2807 Binion Road, Apopka, FL 32703-8504

Reference Pest Control Guides Here

CORDYLINE (TI PLANT)

The ti plant, also known as ti and Hawaiian good-luck-plant, is technically classified as Cordyline terminalis. There are approximately 20 species of Cordyline, which is in the agave family, Agaveaceae. As one reads some of the older horticultural books, it will be noted that the Cordyline was formerly in the lily family, Liliaceae, and earlier, it was classified as Dracaena rather than Cordyline. There are many similarities between Cordyline and Dracaena with regard to their botanical classification and cultural requirements. Cordyline terminalis, a native of east Asia and is the most popular species of the genus for indoor potted plants. Some selections of ti plant are also used extensively as cut florist greens.

Although ti plants represent only a small portion of the potted foliage plant product mix, they are among the most colorful foliage plants. Small-leaved selections of ti plants are finished as small and medium pots for retail market outlets and for use in combination planters. Larger multi-branched plants in 6 to 14-inch pots are produced for large scale interior planting projects.

CULTIVARS

Many of the small plants used in small combination planters are started from seed and are highly variable in color, from green to deep maroon and variegated. Most of the named cultivars in the trade are selections made from unique and attractive seed-grown plants. A few of the named cultivars now popular in the United States are listed below:

`Baby Doll' is a small-leaved cultivar with maroon leaves trimmed with a pink edge.

`Firebrand' is a relatively large-leaved cultivar with dark burgundy foliage.

`Kiwi' is a very popular medium to small-leaved variety with a fine marginal tracery of red around a green leaf with an irregular internal pattern of yellow-green, yellow and ivory stripes which follow the leaf veins. There are also a few fine red lines in the internal pattern on some leaves.

PRODUCTION

Nurserymen presently propagate ti plants by three methods: seed germination, rooting of cuttings, including cane, and finishing micro-cuttings or plugs (TC-4) from tissue culture laboratories.

Ti plant seed is usually available from seedsmen from late summer through early winter. Seed from a few selections of ti will germinate rather true to type and is sold by seedsmen accordingly. Seed are sown in ground beds, raised beds or in trays on benches. They are covered with about 1/4-inch of peat or peat-lite mix which is kept moist until germination and development when the seedlings are large enough to be easily transplanted to small pots, usually about 2 to 4 inches high. There is no reason why seeded flats cannot be placed in chambers for germination, thus utilizing production space more efficiently.

Many of the highly colored named cultivars are propagated by terminal stem cuttings (tips) which are directly stuck in the pots, then eventually sold. Larger plants are stepped up to larger sizes and grown on. Terminal cuttings usually require intermittent mist applications until sufficient roots are present to prevent necrosis of leaf tips and lower leaf loss.

Like several of the dracaena and yucca species, ti plant can also be propagated from cane pieces (large leafless stem cuttings) ranging from a few inches to much larger. Some retail garden outlets offer short sections of ti plant cane packaged in plastic film with instructions for rooting by the consumer on display racks.

Tissue-cultured plantlets of a few ti plant cultivars are offered occasionally by specialists. Since growth of these plantlets is slow and ti plant is a minor foliage plant crop, the interest in using this means of propagation is limited. Most nurserymen feel that it is more feasible to start with large tip cuttings when propagating named cultivars.

Light levels can affect appearance of multi-colored ti cultivars. Cultivars like Baby Doll which normally have dark red leaves with a narrow medium red to pink margin, will begin to produce leaves with wider pink margins as the production light intensity is reduced. Suggested level is about 3000 to 3500 ft-c, which will produce plants with good coloration. Good growth can be obtained with either liquid or slow-release fertilizers at the rate of 2.9 pounds of actual nitrogen per 1000 square feet per month from a 3-1-2 or similar ratio product. Where plants are subject to heavy rainfall or frequent irrigations, the fertilizer level may need to be increased. The potting medium utilized for ti plant should be of good quality, and provide excellent aeration and water-holding capacity. Amendments should include a low to moderate level of micronutrients such as 1 lb Micromax/yd3 and sufficient dolomite to adjust medium pH to 5.5 to 6.5. The higher pH has been shown to be beneficial in reducing fluoride toxicity. Suggested air temperatures for best growth are 65°F minimum to 95°F maximum. Ti can tolerate lower and higher temperatures, but growth rate will be reduced.

PHYSIOLOGICAL PROBLEMS

1) Fluoride toxicity

Symptoms -: The first indication of fluoride toxicity on Cordyline is tipburn followed by marginal necrosis. In severe cases, mottling also occurs within the center of the leaf and the entire leaf may die. Cordyline terminalis `Baby Doll' is the most susceptible cultivar to this problem, although all cultivars have been observed to have symptoms when fluoride is present in water, soil or fertilizer.
Control -: Where fluoride is known to be a problem, the propagation and potting media should have a pH of 6.0 to 6.5 to reduce fluoride availability. Cuttings without roots are likely to take up large amounts of fluoride. Some producers utilize treated water in propagation areas to prevent fluoride uptake during rooting and nontreated water after rooting. To reduce fluoride uptake, use potting media, irrigation water and fertilizers low in fluoride content. Irrigation water should contain less than 0.25 ppm fluoride.
2) Poor color
Symptoms -: Cordyline is popular because it provides various shades of purple, maroon, rose, pink and yellow, as well as green. Intensity (brightness) of any of the colors, except green, under some environmental conditions may be so poor that plants appear dull. Plants also may be mostly dark purple or maroon without highlights of rose or pink common to the cultivar.
Control -: Color intensity appears to be controlled by temperature, light and fertilizer levels. Levels of carbohydrates are low during summer when night temperatures are high and poor color often occurs during this period. Low light intensity, especially during summer, and high fertilizer levels also reduce color intensity. Best color intensity will occur during the period November through May, if suggested light and fertilizer levels are utilized. During periods of poor coloration, some improvement can often be obtained by increasing light intensity and reducing temperature.
3) Damage to terminal growing point
Symptoms -: Growing point appears to die or partially collapses, but eventually regrow.
Control: - This symptom usually occurs after application of a "leaf shine" compound or excess fertilizer which collects in the growing point. Care must be taken to prevent accumulation within the growing point of potentially toxic substances and liquid fertilization should be followed with a few minutes of only water.
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BACTERIAL PROBLEMS: 1) Erwinia blight (Erwinia chrysanthemi, E. carotovora pv. carotovora)
Symptoms -: Systemic infections of Cordyline cuttings with one or both species of Erwinia can occur. These infections result in a combination of symptoms including a wet, mushy leaf spot and stem rot. Lesions on leaves and stems are usually water-soaked and slimy and eventually disintegration occurs. Severe infections can result in cutting loss, since the plants often rot from the cutting end upwards. If these cuttings are carefully recut to remove the rotten portion of the stem and restuck, they will sometimes root adequately. The unfortunate fact, however, is that most of the cuttings will then develop symptoms of stem and root rot caused by Erwinia. Erwinia root rot appears similar to other root diseases with the roots water-soaked and black. Complete disintegration of the infected root system often occurs.
Control -: There are no chemical controls which provide an appreciable degree of symptom relief for any of the phases of Erwinia blight. As mentioned earlier, recutting diseased material only postpones the loss of that material and increases the chances of infection of other healthy material. Carefully examine all cuttings used for propagation, destroying those which are suspected of Erwinia blight. Always use pathogen-free plants for stock as well.
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FUNGAL PROBLEMS: 1) Fusarium leaf spot (Fusarium moniliforme)
Symptoms -: Fusarium leaf spot of Cordyline appears similar to the same disease of dracaenas. Lesions appear only on the immature leaves near the growing tip. Spots are tan to reddish-brown and roughly ellipsoid in shape. In severe cases, the lesions coalesce and become very large and irregularly shaped. A bright yellow halo sometimes surrounds lesions.
Control -: Minimize water applied to plant foliage. If the leaves are kept relatively dry, the disease will not occur. Under overhead irrigation, fungicides may be beneficial but will probably not result in complete disease control.
2) Fusarium stem and root rot (Fusarium sp.)
Symptoms -: Fusarium stem and root rot is caused by a different species of Fusarium than the one causing the leaf spot disease. Initial symptoms include yellowing of the lower leaves and slight wilting. Examination of the root systems reveal blackened water-soaked roots which greatly resemble those infected with Erwinia spp. Stem lesions also appear near the potting medium. Lesions are sunken, tan and wrinkled. They sometimes contain the yellowish spores of the pathogen in powdery masses.
Control -: Minimizing water applications and growing pathogen-free plants in pathogen-free potting medium should be attempted. Since the disease spreads through irrigation water, keep plants on wire benches or other structures which reduce the chances of drainage water contaminating other pots. Always remove and destroy symptomatic plants as soon as they are found.
3) Phyllosticta leaf spot (Phyllosticta dracaenae)
Symptoms -: Lesions are circular to slightly irregular and range from 1 to 5 mm in diameter. They appear mainly on the older leaves of plants and are usually tan with purple borders and yellow halos. Under conditions of high disease pressure, the lesions may coalesce and the entire leaf may die.
Control -: The cultural controls listed for Fusarium leaf spot will also aid in control of this leaf spot disease.
4) Phytophthora leaf spot (Phytophthora parasitica)
Symptoms -: Lesions form mainly on lower leaves close to the potting medium. They are initially water-soaked, brown, zonate areas with irregular margins. Similar diseases caused by this pathogen also occur on schefflera, spathiphyllum, dieffenbachia and philodendron.
Control -: This disease is usually easy to avoid if plants are grown on raised benches away from the native soil. Splashing water from the native soil on to the lower leaves is the mode of infection.
5) Southern blight (Sclerotium rolfsii)
Symptoms -: Southern blight disease appears much the same on one host as another. The pathogen generally attacks the crown of the plant first, sometimes leaving the roots intact and causing girdling and collapse of the tops only. Sclerotia, the fruiting bodies of the pathogen, form all over the infected tissue and appear as small mustard seed-sized bodies. They are first white and turn brown as they mature. The white fan-like mycelium of the pathogen also forms over the plant, potting medium and even sides of benches.
Control -: Chemical control of Southern blight is difficult since the only fungicide which is rarely completely effective and can cause some stunting on some plants. Always discard plants suspected of Southern blight infection and use pathogen-free potting media and pots since the organism lives in soil and can transfer from one crop to the next on recycled materials and equipment.
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INSECT AND RELATED PROBLEMS: The major arthropod pests of C. terminalis include fungus gnats, mealybugs, mites, scales, and thrips. Mealybug, mite, and scale infestations are typically the result of introducing infested plant material into the greenhouse. Fungus gnats and thrips have the ability to fly and thus invade the greenhouse from weeds and other infested plants outside. 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 of Diazinon formulations, Enstar, Gnatrol (a strain of Bacillus thuringiensis), and Vydate L 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) Mealybugs
Symptoms -: Mealybugs appear as white, cottony masses in leaf axils, on the lower surfaces of leaves and on the roots. Honeydew and sooty mold are often present and infested plants become stunted, and with severe infestations, plant parts begin to die.
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.
4) 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 undersurface 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.
5) 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. The Florida red scale is the major scale pest of this plant. It is an armored scale that is reddish-brown to black in color. Feeding by this insect causes a characteristic yellow or chlorotic streak that radiates from the point of attachment.
Control -: See Mealybugs
6) 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.
Control -: See Mealybugs
7) 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.
8) Whiteflies
Symptoms -: Whiteflies are not a major problem but they have been reported as a pest of this plant. Infested leaves often have small yellow spots where adults or immature whiteflies have fed. When populations become dense the leaves become yellowed and lower leaves are covered with black sooty mold. The immature stages of the sweetpotato whitefly are small scale like insects and can be found on the undersides of infested leaves.
Control -: Many materials are registered and effective at controlling whiteflies. To minimize additional resistance problems, one insecticide should be applied two times per week throughout one life cycle (3 weeks) to control an established infestation. Monitor the population to determine if the particular insecticide being applied is reducing whitefly numbers. Some populations may be resistant to one or more of these insecticides. If the infestation persists, use another compound for the above list following the same schedule. Do not apply tank mixes as they may enhance resistance. If low numbers of whiteflies persist, apply one of the above insecticides once per week for 3 weeks then switch insecticides. Undersides of leaves must be covered thoroughly to achieve satisfactory control. For additional information on this pest please consult Plant Protection Pointer #73 (Sweetpotato whitefly on ornamental plants).

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.

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REFERENCES

1. Bailey, L.H. Hortorum staff. 1976. Hortus Third. MacMillan Publishing Company, Inc., New York, NY. 1290 pp.

2. Chase, A.R. 1990. Phytotoxicity of bactericides and fungicides on some ornamentals. Nursery Digest 24(5):11.

3. Chase, A.R., T.J. Armstrong and L.S. Osborne. 1981. Why should you test pesticides on your plants? ARC-Apopka Research Report RH-81-6.

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. 13 pp.

5. Graf, A. 1978. Tropica. Roehrs Company-Publishers, East Rutherford, NJ. 1120 pp.

6. Price, J., D.E. Short and L.S. Osborne. 1989. Management of fungus gnats in greenhouse ornamentals. Extension Entomology Report #74.

7. Reisch, Lisa (Editor). 1991. Florida Foliage Locator 1991-92. Florida Foliage Association, Apopka, FL. 152 pp.

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):1-8].