Maranta Production Guide

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The genus Maranta, a member of the family Marantaceae, consists of approximately 14 to 20 species, depending upon the publication consulted. These clump-forming herbs are indigenous to tropical Americas, primarily South America. In 1975, Maranta, commonly called prayer plant was estimated to represent 3 percent of the foliage plant product mix value in Florida. With the large number of new plants introduced from other genera since 1975, it is estimated that the marantas constitute about 1 to 2 percent of the present product mix volume. Most marantas grown in Florida are produced in central Florida greenhouses.

Marantas are versatile plants indoors because they can be used as small specimen plants, hanging plants which cascade, ground covers in interiorscapes and in dish gardens and other combination planters.

Two cultivars represent over 95 percent of the maranta produced in nurseries for use as foliage plants. The balance is grown by firms which supply the needs of collectors and customers who want something different. The dominant cultivars are Maranta leuconeura `Kerchoviana' and M. leuconeura 'Erythroneura'. All cultivars of Maranta mentioned in this paper are indigenous to Brazil. The stems of this species is not swollen at the nodes and the roots are not tuberous.

Maranta bicolor is a rather rare plant which is occasionally seen in the trade. The plant lacks the tuberous roots, but does have swollen stems at the nodes. The leaves are of similar size and shape to the M. leuconeura species. The leaf blade is dark green above with blotches of light green between the midrib and margin. The underside of the leaf is purple.

Maranta leuconeura `Erythroneura', the red-vein maranta, or red nerve plant, is a colorful cultivar with bright red midrib and lateral veins, a feathered, light greenish yellow central zone and a greenish black outer background. The flowers of this cultivar are purple with a pattern. Other growth characteristics are essentially the same as indicated for `Kerchoviana'.

Maranta leuconeura `Kerchoviana' (listed as `Massangeana' in many of the earlier publications), the prayer plant, rabbit's foot, rabbit's-track or green maranta, is a herbaceous, sprawling plant which grows to form a clump as it matures. Individual stems are nearly vine-like and tend to grow along the potting medium surface or cascade. The stems lack tendrils or holdfasts so they do not climb on vertical surfaces. Leaves are nearly oval shaped, approximately 7 inches long, including the petiole, and 3 inches wide. The petiole is about one third as long as the leaf blade (lamina). The upper surface of the lamina is variegated and satin-like with usually 2 rows of 5 dark green patches. The patches are initially dark brown and turn dark green as the leaves mature. The plant occasionally produces conspicuous, mostly white, modest flowers supported by slender stalks emerging from the petiole sheath.

Maranta leuconeura `Kerchoviana Minima' is a name coined to describe a plant not listed in Hortus, but found occasionally in the trade. The color pattern of the foliage is similar to that of green maranta, except the leaf blade is about one third the surface area, and the internode length is considerable, a character that gives the plant a very open appearance.

Maranta leuconeura `Leuconeura', the silver feather maranta or black maranta, has a light grayish blue green central zone and radiating lateral veins which extend through a greenish black outer background. This cultivar is rather rare in the trade, but very attractive.

Marantas are usually started from cuttings selected from stock beds. Cuttings are commonly provided by tropical American producers or a few local nurseries that maintain stock. Some growers have attempted to grow their maranta stock under the benches used for finished potted plants, with poor results. Growers are not able to maintain adequate and uniform levels of light, water and fertilizer in the under-bench areas and disease and pest management is very difficult in these areas. Stems cut from stock are usually cut down to single-node and double-node cuttings that are generally stuck in hanging baskets. Two cutting are usually used in a 3 to 3 1/2-inch pots and 3 cuttings in a 4-inch.

Maranta are best grown under a light level range of 1000 to 2500 foot-candles in greenhouses where moisture and temperature can be controlled. Temperatures of 70 to 80°F are ideal for maranta rooting and growth. Good growth occurs up to 90°F but is poor above that temperature.

Maranta grow well in a potting medium with good aeration, high water holding capacity and a pH of 5.5 to 6.0. Peat-based mixes generally require addition of dolomite to raise the initial pH and addition of a micronutrient blend product, such as MicroMaxR (1 pound per cubic yard), is recommended. Fertilization of maranta at the rate of 2.3 pounds of nitrogen from a 3-1-2 or similar ratio fertilizer per 1000 square feet per month will provide adequate nitrogen, phosphorus and potassium.

1) Marginal or tip scorch of foliage

Symptoms -

Leaves turn brown at or near the tip and margin. There is usually a transition zone of yellow between necrotic and healthy tissue.

Control -

Avoid excessive soluble salts in root zone and excessively high light intensities and temperatures. Avoid use of superphosphate fertilizers in stock or finishing plants since it supplies fluoride in toxic amounts.

2) Chlorosis

Symptoms -

Plants grown at elevated pH-above 6.0, or with nitrogen sources in mostly nitrate form often have chlorotic younger leaves. This is usually due to insufficient iron (Fe) entering the plant.

Control -

Use iron chelate, reduce soil pH and use ammonium sources for nitrogen.

Reference Pest Control Guides Here

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FUNGAL PROBLEM

1) Helminthosporium leaf spot (Drechslera setariae)

Symptoms -

Helminthosporium leaf spot is frequently a problem for maranta producers using ground beds where plants stay very moist for long periods of time. The lesions first appear as tiny water-soaked areas which turn chlorotic and finally necrotic. Lesions are normally very small (1/16 inch wide or less) and give the affected leaves a speckled appearance. In severe cases, lesions coalesce and form large (up to 1/2 inch) irregularly shaped areas which are tan with a chlorotic halo. High levels of water on leaves are needed for spore germination with at least 6 hours of continuous moisture needed for infection to occur. Most cultivars of maranta are susceptible to this pathogen, as are many species of Calathea.

Control -

Minimizing the period of time leaves are wet can dramatically reduce disease severity. This can best be accomplished by eliminating overhead watering or at least applying water early in the day to allow rapid drying of foliage. Plants which are watered in the late afternoon may remain wet for the entire night, allowing germination and infection of many fungal spores.

Reference Pest Control Guides Here

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VIRAL DISEASE

Symptoms -

CMV causes dramatic symptoms on both red and green maranta. Leaves may be slightly distorted and reduced in size, but the most obvious symptom of CMV infection is the bright yellow patterns formed on the leaves. These patterns are generally jagged and alternate with the normal coloration of the affected leaf. Although Calatheas are also susceptible, the symptoms are generally less apparent and confined to a slight mosaic.

Control -

Although the symptoms of CMV are so striking, there is no evidence that the damage caused is other than aesthetic. The only recommended control is removal of plant material showing these symptoms. Propagation of material with CMV will simply lead to maintenance of the virus since it is spread along with the plant.

Reference Pest Control Guides Here

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NEMATODE PROBLEM

1) Root knot nematode (Meloidogyne javanica)

Symptoms -

Severely affected plants are stunted, with small leaves and yields are very low from stock beds. Examination of roots of nematode infected plants reveals "knots" on the roots giving them the appearance of a string of beads.

Control -

Several nematicides have been tested for control of root knot nematodes on maranta. Effective treatment of ground beds was not as easily achieved as that of containers on raised benches.

Reference Pest Control Guides Here

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INSECT AND RELATED PROBLEMS

The major arthropod pests of these plants include caterpillars, root mealybugs, mites, and scales. Mealybug, mite, and scale infestations are typically the result of bringing infested plant material into the greenhouse. Adult forms of caterpillars 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. Because the potential for phytotoxicity exists, a small group of plants should be tested for phytotoxicity prior to treating the entire crop (See Chase et al. 1981). The list given in this section should be used only as a guide to the sensitivity to pesticides.

1) Caterpillars (worms)

Symptoms -

Infestations are easy to detect because worms, their excrement and the damage they cause, are usually quite visible to the unaided eye. Damage appears as holes in the center or along the edges of leaves. If leaves have been fed upon while in the rolled stage the damage appears as a line of equally spaced holes once the leaf opens. Damage by worms is often confused with slug or snail damage. The only way to determine which pest is involved is to find a specimen. Old damage can be distinguished from new by the calloused appearance of the older damaged areas (worms are usually gone by this time).

Control -

2) 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.

3) 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

Symptoms -

Mites are very small and go unnoticed until plants become severely damaged. The mite Steneotarsonemus furcatus can be a serious problem. The early signs of damage appear as water-soaked lesions or a necrotic line that parallels the margin of the leaf. Severe infections will kill the plant (See Denmark and Nickerson 1981). These plants are also subject to damage by the two-spotted spider mite. Affected plants turn yellow or speckled due to the feeding of this pest. Webbing, loss of leaves and plant death can occur when mite populations reach high levels.

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.

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.

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.

7) Snails and Slugs

Symptoms -

Snail, slug and caterpillar damage are similar and determining which pest is present can be difficult. Snails and slugs are voracious feeders, with small stages feeding on surface tissue and larger ones eating irregular holes in foliage. Generally, the culprit can be found on close examination of the plant. Slugs often live under benches or in dark, moist protected places close to the damage. These pests are nocturnal and can be found feeding at night.

Control -

Sprays or baits applied to moistened soil around plants are effective. Repetitive applications are necessary. Good sanitation with removal of extraneous plant material and debris which might shelter these pests aids in control.

8) 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.

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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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Reference Pest Control Guides Here

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REFERENCES

1. Bailey, L.H., E.X. Bailey and Staff of Liberty Hyde Bailey Hortorium. Hortus Third. Macmillan Publishing Company, Inc. New York, NY. 1290 pp.

2. Chase, A.R. 1990. Phytotoxicity of some bactericides and fungicides on ornamental plants. 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-Revised. 13 pp.

5. Denmark, H.A. and J.C. Hickerson. 1981. A tarsonemid mite, Steneotarsonemus furcatus DeLeon, a serious pest on Maranta sp. and Calathea sp. (Acarina: Tarsonemidae). Proc. Fla. State Hort. Soc. 94:70--72.

6. Short, D.E. and L.S. Osborne. 1989. Phytotoxicity of insecticides and miticides to foliage and woody ornamental plants. Extension Entomology Report #57. 23 pp.

7. Short, D.E., L.S. Osborne and R.W. Henley. 1991. 1990-92 Insect and related arthropod management guide for commercial foliage and woody plants in Florida. Extension Entomology Report #52. 13 pp.

8. 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]

9. Smith, Cecil N. and J. Robert Strain. 1976. Market outlets and product mix for Florida foliage plants. Proc. Fla. State Hort. Soc. 89:274-278.