Bird's Nest Fern

CFREC-A Foliage Plant Research Note RH-91-7
R.T. Poole, 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

Bird's Nest Fern

Ferns have always been an important segment of the foliage industry. The Boston fern, Nephrolepis exaltata, was one of the first ferns grown commercially for export and there are now many other fern species, including Bird's-nest fern, produced and sold in large quantities. Bird's-nest fern, Asplenium nidus, is a large epiphytic fern, with erect, simple, wavy, bright green leaves which can reach lengths of 4 feet. Asplenium nidus `Crispafolium', the wavy Bird's-nest fern, is similar to Bird's-nest fern but fronds are much wavier.

PRODUCTION

Asplenium are produced from spores. Sphagnum or peat moss are good substrates for spores, but peat moss as a medium is improved by the addition of 100 grams of dolomite per cubic foot. Spore germination should take place in about 2 weeks if temperatures are 70-80°F. Only fresh spores should be used. High humidity can be maintained by covering flats with glass or plastic, but use of intermittent mist 15 sec/30 min during daylight is preferred. If glass or plastic is used, the cover should be removed 4-6 weeks after sowing, and the young fern misted. Due to the wide, robust fronds and spreading habit from a central axis, one plant is usually placed per container.

Mature fern can tolerate high light levels, but grow best between 2,000 and 4,000 ft-c. A potting medium high in organic content, e.g. peat: bark (2:1 by volume), that has a highwater-holding capacity and good aeration produces attractive fern. The benefits of additional micronutrients are questionable and if added should be supplied at low rates. Bird's-nest fern apparently get sufficient micronutrients from irrigation water and potting medium. Although fern are commonly grown in highly acidic soils, recent research indicates a pH of 5.0 to 5.5 is preferred. Addition of 3.5 pounds of dolomite to a cubic yard of a mix with a large percentage of acid peat will usually result in a mix with a pH of 5.0 to 5.5. The suggested fertilizer level is 1200 lb N/A/yr from a 1-1-1 ratio fertilizer (about 2.5 lbs N/1,000 ft2/month). For constant fertilization 100-200 ppm N is sufficient.

The best temperature for Bird's-nest fern growth is 70-90°F. Temperatures slightly outside of this range will not reduce plant quality but will reduce growth rates. High humidity should be maintained.

PHYSIOLOGICAL PROBLEMS

1) Flat or crinkled fronds

Symptoms -

Fronds are either very flat or extremely crinkled.

Control -

Although the crinkle or wavy habit of the fronds is influenced by genetics, high light will increase severity of crinkling while low light levels will cause fronds to be much smoother. Alter light levels to achieve the desired frond flatness.

2) Multilobed fronds

Symptoms -

Fronds appear multilobed with indentations. Tips of fronds may be crinkled and clear and sometimes necrotic.

Control -

Excessive amounts of fertilizer (soluble salts) cause these symptoms. Reducing the amount of fertilizer applied and leaching the potting medium are recommended for this problem. In addition, plants may be transplanted to new potting media and left unfertilized until normal growth returns.

3) Tipburn

Symptoms -

Fronds have necrotic areas, usually on tips but sometimes along margins.

Control -

A dry medium and high rates of fertilizer are the most frequent cause of tipburn. Reducing nutrients and leaching the potting medium will alleviate high soluble salts. Dry soil will also cause these symptoms. Copper toxicity has also produced necrotic edges on Bird's-nest fern. Pesticides containing copper should be tested on a few plants to evaluate toxicity of each material to be used on your crop.

BACTERIAL PROBLEM

Reference to University of Florida/IFAS Pest Control Guides

1) Bacterial blight (Pseudomonas cichorii or P. gladioli)

Symptoms -

Foliar lesions caused by these two bacterial pathogens are nearly identical and the diseases can be treated the same. Small water-soaked, translucent spots form on leaves. Lesions enlarge rapidly to 1/8 inch in diameter and turn red brown with a purple margin. When conditions are wet and warm, these lesions frequently coalesce and may spread along veins encompassing large portions of fronds. They can be vein delimited spreading over one side of the leaf without crossing the central leaf vein.

Control -

Elimination of overhead watering is one of the most effective control methods for bacterial blights. Pseudomonas gladioli blight can be harder to control than P. cichorii blight even when leaves are kept dry. Applications of bactericides such as copper or antibiotic products are generally ineffective. Always use pathogen-free plants for production and destroy symptomatic plants as soon as they are discovered.

NEMATODE PROBLEM

Reference to University of Florida/IFAS Pest Control Guides

1) Foliar nematode (Aphelenchoides fragariae)

Symptoms -

Lesions caused by foliar nematode are sometimes similar to those caused by the bacterial pathogens described above. Small, water-soaked spots form generally near the frond base. Lesions rapidly turn brown to black and distortion of the fronds may occur if large areas are infested. Affected tissues remain turgid and do not collapse. Spread of the nematode within the leaves is usually inhibited by large leaf veins making lesions somewhat angular and vein delimited.

Control -

The most effective control for foliar nematode on Bird's-nest fern is destruction of infected plants. These organisms easily contaminate potting media and pots and bench surfaces covered with organic matter. Sanitation between crops can greatly reduce nematode spread from one crop to the next. In addition, avoid producing plants in contact with the ground since it can be a source of nematodes as well.

INSECT AND MITE PROBLEMS

Reference to University of Florida/IFAS Pest Control Guides

The pests of Bird's-nest fern are of relatively minor importance, but include caterpillars, fungus gnats, mealybugs, scales and slugs. Mealybug and scale infestations are typically the result of bringing infested plant material into the greenhouse. In the control section for each pest a few of the registered and effective pesticides are listed. For a more complete listing, please consult the references at the end of this report. No information is available concerning phytotoxicity of pesticides for insects and slugs on Bird's-nest fern.

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. 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) Scales

Symptoms -

Infested plants become weakened or stunted. 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 some scales are hard to distinguish from the plant material on which they feed.

Control -

See Mealybugs

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 are 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) Slugs

Symptoms -

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.

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 to University of Florida/IFAS Pest Control Guides

REFERENCES

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

2. Chase. A.R., J.W. Miller and J.B. Jones. 1984. Leaf spot and blight of Asplenium nidus caused by Pseudomonas gladioli. Plant Disease 68:344-347.

3. Miller, J.W., A.R. Chase and J.B. Jones. 1984. Leaf spot and blight of Bird's nest fern. Plant Pathology Circular No. 256. Florida Department of Agriculture and Consumer Services.

4. Papenhagen, A. 1986. humidity has a marginal effect on plants. Gb + Gw (36):1343- 1346.

5. Poole, R.T. and C.A. Conover. 1983. Fertilization of Bird's nest fern. ARC-Apopka Research Report RH-83-18.

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

7. 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.

8. Short, D.E., L.S. Osborne, and R.W. Henley. 1989. 1989-90 Insect and related arthropod management guide for commercial foliage plants in Florida. Extension Entomology Report #53.

9. 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]