Araucaria heterophylla (Norfolk Island Pine or Australian Pine) is a southern hemisphere conifer native to the Norfolk Islands and Australia. This tree has been referred to incorrectly as Araucaria excelsa for a number of years. Norfolk Island Pine is one of the few conifers able to adapt to interior environments, and is able to tolerate relatively low light levels. In its native habitat, this tree may reach 200 feet in height and grows in full sun, although seedlings can survive for years in the low light understory. Norfolk Island Pine is salt tolerant and this no doubt relates to its ability to grow along the coast in its native habitat. This tree is commonly available from foliage plant producers, but there is another species (Araucaria bidwillii [Bunya - Bunya Pine]) that is also available in small numbers. Most people consider the Norfolk Island Pine the more attractive of the two species and it is easier to grow.

Propagation of Norfolk Island Pine is by seed which germinates fairly rapidly (10-15 days). Seed should be placed flat on the germination medium without covering and lightly misted or fogged until the tap root emerges and top growth is initiated. At that time, seedlings can be irrigated as needed to keep the medium moist. Suggested light level for propagation is 50% shade (5000-6000 ft-c). Often about 5% albino seedlings will germinate and these will die or can be discarded when potting seedlings.

Potting media used for Norfolk Island Pine must be supportive of trunks and help make up for the limited root systems of these trees. A mixture such as 3:1 peat:sand will help keep trunks straight, yet provide good water and fertilizer retention. Mixes with slightly more aeration should be used for seedling trees, but care must be taken not to transplant them before they start leaning because of weak root systems. Media should be amended to include a moderate level of micronutrients such as 1 to 1 1/2 lbs Micromax/yd3 and sufficient dolomite to adjust medium pH to 5.5 to 6.5. Iron (Fe) deficiency in the growing tips has been observed when pH levels were above 7.0.

Norfolk Island Pine will tolerate a wide temperature range. High temperatures (95° to 105°F) have been observed to cause noticeable tip damage if accompanied by dry winds and clear skies, whereas low temperatures (30° to 32°F) can cause growing point abortion. Temperatures below 25°F can cause severe freeze damage, especially if accompanied by wind. Suggested production temperatures are 60° to 90°F for seedlings and liners and 45° to 90°F for potted trees. Light levels can also have a tremendous effect on growth and appearance. Trees grown in full sun will be compact, have a strong trunk and a light to medium green color, whereas shade grown plants have a more open appearance, a weaker trunk and dark green foliage. Producers usually stake trees in 3 gallon pot sizes and larger because they do not form a strong root system and plants often lean, causing unsightly bending of the growing terminal. Although we recommend production in 4000 to 8000 ft-c (30 to 63% shade), this is generally best for trees grown in 4 to 8 inch pots. Larger trees can be grown in full sun and acclimatized in shade for several weeks before placement indoors, or grown under 30% shade.

Fertilization regimes required depend on light intensity utilized. The suggested fertilizer rate for trees grown in 4000 to 8000 ft-c (30 to 63% shade) is 1500 lb N/A/yr from a 3-1-2 ratio fertilizer source: liquid or slow-release (equivalent to approximately 34 lb N, 12 lb P2O5 and 23 lb K2O/1000 ft2/yr. When trees are grown in full sun to 30% shade the fertilizer level should be increased from 25 to 40%; the higher amount is suggested for full sun grown trees. When trees are grown in full sun the symmetry is often better, but color, is often yellowish-green or light-green unless fertilizer level is increased, and even then acclimatization is necessary to obtain desired color.

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PHYSIOLOGICAL PROBLEMS

1) Leaning trunks

Symptoms -

Trunks are loose in pots causing trees to lean and develop bent growing points.

Control -

Moderately tight potting media, proper fertilization, adequate light intensity and protection from wind will all contribute toward prevention of leaning trunks. If these methods are not adequate to control leaning, the trees will have to be staked.

2) Micronutrient deficiency

Symptoms -

Chlorotic growing points on the main tip as well as on lateral branches.

Control -

Use of micronutrients is suggested in the potting medium or in the fertilization program.

3) Insufficient light

Symptoms -

Although the main trunk may be straight, side branches droop excessively and plants lack proper development.

Control -

Provide higher light intensity, at least 6000 ft-c or 50% shade, for trees more than 6 inches tall.

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FUNGAL PROBLEMS

Reference Pest Control Guides Here

1) Anthracnose (Colletotrichum derridis)

Symptoms -

Needle necrosis or anthracnose begins as small necrotic areas on needles. Large portions of branches may turn brown and needles abscise readily. Fruiting bodies (acervuli) of the pathogen form in the necrotic areas and appear as tiny black specks. These can be seen with the naked eye.

Control -

Elimination of most exposure to overhead irrigation or rainfall can control this disease.

2) Root rot (Cylindrocladium and/or Pythium spp.)

Symptoms -

Plants lack vigor and may wilt or grow slowly or not at all. Root systems of affected plants are stunted and brown to black with loss of many feeder roots. Roots may also be mushy and fall away easily when the potting medium is examined.

Control -

Use standard techniques for cultural control of root diseases such as new or sterilized pots, and potting media as well as healthy seedlings.

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INSECT AND MITE PROBLEMS

Reference Pest Control Guides Here

The major arthropod pests of this plant include mealybugs, scales, and thrips. 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 in this section should be used only as a guide to the sensitivity to pesticides.

1) 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.

2) Mites (Broad mite and false spider mites)

Symptoms -

Mites are very small and go unnoticed until plants become severely damaged. Broad mites cause distortion and necrosis of the vegetative shoot apex. Broad mite eggs are covered with many tubercles which give them the appearance of being jeweled. False spider mites (Brevipalpus spp.) are red in color and sedentary. Eggs are bright red and oval-shaped and are laid on both surfaces of leaves. Initial infestations are indicated by faint brown, scruffy flecks, later becoming bronze or reddish in color. Basal leaf areas are affected, vegetative shoot apexes may be killed, and severe leaf drop may occur.

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.

3) 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

4) 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.

4) Mites (Broad mite and false spider mites)

Symptoms -

Mites are very small and go unnoticed until plants become severely damaged. Broad mites cause foliar necrosis of the vegetative shoot apex. Initial symptoms of injury show new leaves cupped downward, puckered, stunted and have serrated margins. Broad mite eggs are covered with many tubercles which give them the appearance of being jeweled. False spider mites (Brevipalpus spp) are red in color and sedentary. Eggs are bright red and oval-shaped and are laid on both surfaces of leaves. Initial infestations are indicated by faint brown, scruffy flecks, later becoming bronze or reddish in color. Basal leaf areas are affected, vegetative shoot apexes may be killed, and severe leaf drop may occur.

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.

Reference Pest Control Guides Here

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

2. 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.

3. 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.

4. 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 12(9):1-8].