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ANTHURIUM
PROPAGATION |
INTRODUCTION: Anthuriums are Neotropic herbaceous perennials, and are the largest genus (more than 1000 species) of the Araceae family. Once considered a novelty flower, AnthuriumsBwith their bright, vibrant colors and 1950s-lawn-chair ambianceBare now in great demand, and they play an important role in the floriculture, potted-plant and interiorscape industries.
Anthuriums, however, are not the easiest plant to propagate, and the environment in which they thrive is one where pathogens flourish. In addition, the Anthurium is considered a Along-term@ crop; for a propagator to get a Ajust-stuck@ cutting to a propagated plant ready for sale takes (at best) months. The longer the Anthuriums have to be kept in the propagator=s facility, the more opportunities there are for disease outbreaks and subsequent losses.
Therefore, there are many issues to be considered when evaluating propagation methods for Anthuriums.
This report will be separated into three sections:
$ Basic propagation options for the Anthurium.
$ Potential pathogen/disease problems and sanitation recommendations.
$ General culture requirements of Anthuriums.
PROPAGATION METHODS
There are three basic approaches to propagation of Anthurium:
1. Propagation by seed.
2. Propagation by traditional vegetative methods (division, cuttings, layering).
3. Propagation by tissue-culture methods.
1. PROPAGATION BY SEED. Propagation of Anthurium by seed is an extremely lengthy process, which would considerably drive up the costs of propagation. In addition, unless the propagator is hot on restricting the crosses (almost all Anthurium are forced to cross-pollinate because the pollen is ripe at a time later than the stigma is receptive), the progeny of seed propagation will be variable.
The only instance in which seed propagation would be of benefit to the commercial propagator would be if the propagator was also the breeder and had hand-pollinated a particularly interesting cross which they were then going to send to the tissue-culture lab for mass plantlet/microcutting production.
However, if one wanted to propagate by seed, the following is the process, in brief. If further details or methodology is needed, I will be happy to furnish them excruciating detail.
1. The spadix is composed of a multitude of flowers, which are perfect (two-carpelled ovary, four anthers). When mature, the stigma looks like a rounded protuberance on the spadix. When they are ready for pollination, they appear damp and shiny.
2. To pollinate the Anthurium, one can either trust to natural pollinators to do the job, or hand-pollinate. If one wanted to be sure of the progeny, one would have to hand pollinate and isolate the plant(s) from potential pollination from other sources. There are different methods for accomplishing this. Hand pollination can be done by collecting the pollen and then, when the Amother@ plant is ready for pollination, using a brush to brush the pollen on the Amother@ flowers.
3. Once pollination occurs, the spadix takes on a Awarty@ appearance.
4. After six to seven months, the spadix will produce many mature, two-seeded, yellow berries.
5. Collect the berries and squeeze them to express the seeds.
6. Scatter the seeds on finely shredded organic material (tree fern fibers, for example).
7. The seeds germinate very quickly (days).
8. They are ready for transplanting in four to six months.
9. It often requires up to two-and-a-half to three years for the majority of seedlings to reach flowering stage which, for the grower, is the time when the Anthurium is optimally marketable.
2. PROPAGATION BY TRADITIONAL VEGETATIVE MEANS (CUTTINGS, DIVISIONS, LAYERING): Until the advent of tissue propagation, traditional vegetative propagation was the method of choice for propagation of Anthuriums. Disadvantages of this approach to propagation were the length of time necessary to get a marketable plant, the costs involved with maintaining the plants during that period of time, and the costs of maintaining a stock-plant nursery adequate for the propagator=s needs. Now that reasonably priced tissue-propagated microcuttings are available for the propagator, the length of time from propagation to marketable plant can be greatly decreased, as are the numbers of disease-free propagules available for the propagator, if the propagator uses tissue-propagated microcuttings.
However, if one wanted to propagate by traditional cuttings, divisions and layering, these are the methods available.
Cuttings. The usual cutting is to Atop@ the plant (remove the upper-most stem and a few leaves). Of all the traditional (non-tissue-propagated) propagation methods, this produces a flowering plant in the shortest amount of time. However, the numbers of propagules for this method are limited to the numbers of stock plants you have available to Atop.@ Once obtained, the Atopped@ cutting is then rooted in well-aerated media, with roots developing within two to three weeks, and the first flower is produced in about six months. The basal part of the stem then develops offshoots or suckers, which is a natural tendency of the species, but can also be influenced by environment. When Atopped@ cuttings are taken from juvenile plants, there is more subsequent sucker development.
Basal stem cuttings (consisting of one or two leafless nodal sections, placed horizontally on well-aerated media) will produce plants from each node. More plants can be developed from basal cuttings; however, because of the juvenility of the tissue in basal cuttings, it will take longer for the basal-node propagated plant to flower (two to three years).
Layering. Once the stem has reached sufficient size, place it on its side in damp media to encourage the production of new plants (a plant will be produced from each stem node). Once roots and shoots have developed, detach the new plants from the donor plant, and plant as separate plants.
Division. Anthurium will usually produce lateral shoots from the basal part of the stem of the plant. Some species more readily produce lateral shoots than other species. Gibberellic acid has been used to stimulate lateral shoot development with some success. Once an offset has developed a few roots, it can be excised and planted as a new plant. The length of time between division and flowering is usually a matter of months (compared to years for propagation by seed).
See the section entitled GENERAL ANTHURIUM CULTURE REQUIREMENTS for information regarding media, humidity, light requirements, etc.
3. PROPAGATION BY TISSUE-CULTURE METHODS. With the advent of tissue-cultured Anthuriums, large numbers of Anthurium clones became available for a reasonable price. Tissue-culture laboratories (such as AgriStart, Twyford and Oglesby) do the extensive work (and make the extensive investment in equipment and personnel) necessary to produce a variety of different-staged Anthurium Aplants.@ Tissue-culture laboratories produce tissue-propagated plants/plantlets at four different stages; the stage the buyer selects should be in accordance with the care the buyer is able to give to the plantlet to get it to a viable, saleable condition.
The basic approach to tissue-culture propagation is that the laboratory takes a desirable cultivar, harvests tissue and, under rigorous aseptic conditions and controls, produces massive numbers of clones which are disease-free.
I would estimate that the costs associated with starting and running a tissue-culture lab would be enormous. The advantages of tissue-propagation, however, in long-term crop plants like Anthurium, which take extended periods of time for traditional propagation (by seed or traditional vegetative means), are many, and include:
$ The ability to produce massive quantities of clones of desired cultivars in a very short amount of time. This would be important for the initial release of a new cultivar, for instance.
$ The ability to produce disease-free propagated plants.
$ The ability to very tightly coordinate uniformity of propagated plant stages by the nature of the tightly controlled propagation environment.
If there is interest in setting up a tissue-propagation laboratory, a more in-depth analysis of that possibility would be warranted.
For information regarding the basic considerations when designing and constructing a tissue-culture laboratory, I would recommend an article originally published in the Proceedings of the International Plant Propagators Society, Vol. 37 (1987), pp. 462-467, ADesigning a Plant Micropropagation Laboratory,@ which can be found on the Texas A&M Plant Tissue Culture Information Exchange website at:
http://aggie‑horticulture.tamu.edu/tisscult/microprop/facilities/microlab.html
The Texas A&M Plant Tissue Culture Information Exchange website also has a wealth of information available, including links to websites for many of the major tissue-culture labs. The URL for this website is:
http://aggie‑horticulture.tamu.edu/tisscult/microprop/microprop.html
It is possible for a propagator to take advantage of the tissue-cultured Anthurium benefits without running their own tissue-culture lab: the youngest two stages of plantlets sold by labs are basically very small, tender, shoot cuttings. By purchasing these Amicrocuttings,@ the Anthurium propagator could have a constantly available supply of dependable, disease-free cuttings at a reasonable cost.
Tissue-cultured plantlets (or microcuttings) need special handling and care during the hardening-off process from the lab to the greenhouse to prevent losses and ensure plant-stage uniformity. The laboratory is a stress-free environment for the plantlets. Therefore, they need to be progressed across a gradient of decreased humidity, and increased light and typical greenhouse stress conditions, to the point that they can tolerate a typical greenhouse environment.
The following is an outline of the stages of Aplantlets@ available from tissue-culture labs, and what is necessary to harden them off and get them to a viable greenhouse-tolerant status. The plantlets fresh from the aseptic conditions of the laboratory are quite vulnerable to pathogens. Therefore, rigorous sanitary handling of the plantlets is necessary to prevent outbreaks of disease and loss of plantlets.
Stage II plantlets, or Amicrocuttings,@ are unrooted and need immediate attention once they arrive from the tissue-propagation lab. Stage II plantlets are basically cuttings without roots, but also without cuticle; they will need high humidity to survive. Mist or fog systems are necessary, with lengthening of the interval between misting as the plantlets become acclimatized. Plastic film can also be placed over the community trays of plantlets, but air circulation must be provided, as well, to decrease heat build-up. In addition, plantlets grown in the laboratory are grown under 200-600 foot candles of light and kept at 78 degrees F. Therefore, during the acclimatization process, the plantlets must be also moved along a gradient of temperature and light variation. It is recommended that the light levels be doubled very one to two weeks until the plants are able to tolerate normal light intensity. Stage II plantlets (which are actually shoot cuttings) should have the apex and two or three leaves before they are transplanted from the culture medium. Stage II plantlets are extremely delicate, and forceps with felt pads may be necessary to stick the most delicate ones. They should be stuck just deep enough to anchor them, and a spray water bottle should be used to mist the plantlets during handling. The media should be clean, and can be a product such as Oasis, rockwool, or Perlite-containing media. Once they are completely stuck in the community flat or tray, water them in gently with a very dilute (100-150 ppm) solution of 20-20-20 fertilizer solution (plantlets are very susceptible to damage from fertilizer until they develop cuticle and roots). Bottom heat will facilitate the formation of roots. They should then be placed under high humidity and progressed to tolerate 80% shade (1500-2000 foot candles).
Stage III plantlets have been initially rooted in vitro, are generally hardier than unrooted propagules (Stage II) and, when received from the lab, can be held in a controlled environment for a few days without risking degradation of quality. Stage III plantlets are rooted in a high-sugar-concentrated media. Therefore, when received from the lab this must be gently washed off before they can be planted. Plantlets with intact roots may be treated with a fungicide as a preplant soak or postplant drench. Plants with intact roots can be transplanted to a variety of media (Oasis or rockwool plugs, shredded tree fern fiber, planting mixes with #2 Perlite/3:1), and placed under 80% shade with high humidity.
The media should not become waterlogged, and a regular fungicide program should be instituted to prevent root- and stem-rot problems. Initially, the environment should be at 80 to 85 degrees F (day) and 70 to 75 degrees F (night). Bottom heat will also assist in stimulating rooting of the plantlets.
As the plantlets develop and harden off, the humidity should be gradually decreased. Plants should continue to be protected from the rain (i.e., grown under cover) until they are large enough for transplant into beds or pots.
Stage II and Stage III plantlets could be an excellent source of disease-free clonal vegetative Acuttings.@ However, cost considerations would need to be evaluated to judge for cost-effectiveness of purchasing one stage of tissue-cultured plantlet compared to other stages. For instance, Oglesby=s price difference between Stage II and Stage III, and Stage III and Stage IV, plants is about 27%. The ability to acclimate Stage II plantlets is stated to be dependent on the cultivar, and the delicate handling required would need to be taken into consideration. All three stages of tissue-cultured plants are susceptible to disease, rain and slug damage, and salt burn from use of undiluted complete fertilizer. Oglesby=s indicates that, once the plantlets are transplanted, there is no demonstrable difference in growth times, comparing Stage II and Stage III plantlets. Oglesby=s also indicates that the majority of their sales are Stage II plantlets.
Stage IV. Because the hardening-off process is not easily accomplished, is fraught with opportunities for problems, and would require a specific environment to be successfully accomplished, most tissue-culture labs produce Stage IV plants. For instance, Oglesby has installed 100,000 sq.ft. of greenhouse space to produce Stage IV (acclimatized) plants. The Stage IV plants are acclimatized tissue-culture plants, and are sold 50-cells, 72-cells or 92-cells to a tray.
Prices for tissue-culture Anthurium. Oglesby=s price list for 2002 are as follow:
Stage II: From 37 cents each to 42 cents each.
Stage III: From 47 cents each to 54 cents each.
Stage IV: From 60 cents each to 98 cents each.
Crop-finish time depends on the cultivar, pot size and growing environment. For a grower to achieve a Afinished@ A. andreanum plant (pot size of 6"), Oglesby estimates it to take eight to ten months when using the 72- or 92-cell-tray (Stage IV) young plants. This is a considerably shorter length of time than that required by either propagation by seed or propagation by traditional basal-node cuttings; it is about the same length of time as that required for Atopped@ cuttings and division of lateral shoots; however, the ability to access great numbers of traditional division or Atopped@ cutting propagules is limited, while the ability to access great numbers of tissue-propagated propagules is virtually unlimited. A. scherzeranum is usually grown in 3-1/2" to 6" containers and will Afinish@ in four to seven months.
POTENTIAL PROBLEMS: PATHOGENS/ DISEASES
The environment in which Anthurium propagation and cultivation is conducted is perfect for pathogen infestations and diseases. Therefore, as important to the Anthurium propagator is the selection of disease/pathogen-resistant cultivars, and maintaining facility sanitation measures to attempt to prevent problems before they occur, it is equally important to have an aggressive IPM program, with constant vigilance for evidence of outbreaks of pathogen infestation or disease. Some of the problems which commonly afflict Anthuriums spread rapidly once they start, and often even what appears to be a minor infestation will mean needing to destroy the plant and sterilize the area in which it grew. If the diseased plant is in a community tray, the losses could be significant.
The following are some of the known pathogen-related problems associated with Anthuriums. For more detailed information on these diseases/pathogens, and detailed information on how to treat them (if possible) if they occur, I recommend the following two excellent university-affiliated websites:
University of Hawai=i Crop Knowledge Master/ Pests/ Anthurium (web page under construction):
http://www.extento.hawaii.edu/kbase/crop/crops/anthuriu.htm
University of Florida: Pest Control Guide
http://www.ifas.ufl.edu/~apkweb/pestlink.htm.
Bacterial problems:
$ Soft rot (Erwinia carotovora subsp. carotovora).
$ Xanthomonas blight (Xanthomonas campestris pv. dieffenbachiae).
Fungal problems:
$ Anthracnose (Colletotrichum gloeosporioides).
$ Phytophthora leaf spot, flower blight, root rot (Phytophthora parasitica).
Viral problems:
$ Tomato spotted wilt virus.
Nematode/ insect problems:
$ Burrowing nematode decline (Radopholus similis).
$ Foliar nematode (Aphelenchoides fragariae).
$ Aphids.
$ Fungus gnats.
$ Mealybugs.
$ Mites (two-spotted spider mite).
$ Scales.
$ Shore flies.
$ Thrips.
$ Whiteflies.
RECOMMENDED SANITATION MEASURES: In addition to the normal sanitation measures employed in a propagating facility (i.e., pasteurized or sterile media, sanitized work surfaces and tools, avoidance of working in a contaminated area prior to entering the propagation facility, water draining away from the propagation facility, keeping trimmings and other rubbish cleaned up, off the floor, in covered trash cans, etc.), the following sanitation practices are recommended to help prevent the occurrence or spread of the pathogen-related problems associated with Anthurium propagation.
1. Keep foliage dry, if possible. Drip irrigation is preferable.
2. Avoid condensation with the use of fans, if necessary.
3. Avoid hanging plants above the Anthurium plants.
4. Avoid high-nitrogen fertilizers which make plants more susceptible to infection.
5. Sanitize shoe wear before entering propagation facility, or provide disposable surgical booties to cover shoe wear.
6. Employ appropriate methods to avoid soil-borne contamination from vehicular tires being transported into the propagation facility.
7. Daily rogue out infected plants.
8. Be sure to isolate potentially infected crops introduced to the facility (i.e., Aglaonema imported from the tropics).
9. In-house propagation of Aglaonema and Diffenbachia should be kept far away from tissue-cultured plants, if utilized.
10. To avoid spread of pathogens by splashing water:
A. Anthuriums should be grown/propagated in an enclosed or covered facility to prevent rainwater splash.
B. Anthuriums should be grown/propagated on raised benches.
C. Ample walking space between benches should be provided to avoid workers= clothing brushing against a contaminated plant and then transferring it to another plant; avoid unnecessary traffic in the aisles between the plants.
D. Ample space should be maintained between plants both to ensure adequate air circulation and to allow adequate coverage with pesticide should the plants need to be treated.
11. Preventative maintenance programs of copper-based fungicides, alternated with bactericides, can help prevent infection (NOTE: Copper, and many chemicals/ pesticides, can be phytotoxic to Anthurium; always test a small batch of plants first before instituting a program, and allow four weeks for the phytotoxic symptoms to appear).
12. Preventative programs for mites, snails, slugs, worms, thrips and white flies should be utilized. Cultural conditions and cultivars will dictate which chemicals can be safely used. Always test a new chemical on a small batch of plants first before implementing the chemical in a greenhouse-wide program.
13. While tissue-cultured plantlets are usually free of disease, they can pick up pathogens in the hardening-off phases. Therefore, especially if you purchase Stage II and up plantlets, it is always best to isolate each new addition of plant material to a propagation/growing facility until infection-free status is confirmed.
GENERAL ANTHURIUM CULTURE REQUIREMENTS
Fertilizing/ nutrition. In general, high nutrient levels should be avoided, especially on the young plants. Liquid fertilizer on a constant-feed program, according to Oglesby=s recommendations, should not be more than 250 ppm of nitrogen. Mature plants can handle as high as 400 ppm occasionally, but must alternate with regular watering. Tests have demonstrated that higher rates of nitrogen produce thick, deformed leaves and lighter flower colors. If overhead irrigation is used to apply the fertilizer, a quick water rinse should follow to prevent leaf damage from the liquid fertilizer remaining on the leaves.
Because the Anthurium is considered a Along-term@ crop, careful consideration should be paid to estimated duration of time the Anthurium plants will be in the propagator=s facility, and fertilizer applications planned appropriately, in order to avoid deficiencies. In addition, Anthurium requirements for magnesium are higher than most foliage crops, especially in warmer climates. Oglesby=s recommends 10 pounds dolomite and 3-1/2 pounds of Hi-Cal lime per cubic yard of media to provide a balanced calcium-magnesium ratio, as well as regular foliar applications and/or top-dressing of magnesium sources.
Temperature. Anthurium plants will not tolerate frost or a freezing environment. They produce the best growth in day temperatures of 78 to 90 degrees F and night temperatures of 70 to 75 degrees F. Hotter daytime temperatures may produce burning of the foliage, faded flower color, and decreased flower life. Night temperatures between 40 to 50 degrees F may produce slower growth and yellow lower leaves. Scherzeranum cultivars are the exception, and do best in slightly lower temperatures (68 to 80 degrees F during the day and 60 to 70 degrees F at night).
Light intensity. The optimum light intensity for Anthuriums is dependent on the cultivar, the elevation, the temperature, and the nutrition of the plant. As a rule, most Anthuriums grow well between 1500 to 2500 foot candles of light intensity; higher light intensities can produce fading of leaf and flower color. Scherzeranum cultivars do best between 1000 and 1500 foot candles of light intensity.
Media. Anthuriums grow best, with the least problems, in well-aerated media that retains water, and has excellent drainage. The media should be able to anchor the roots and stem, and provide adequate moisture, nutrients and aeration to the plant. Recommendations for growing media include organic matter (shredded tree fern, nut shells, wood chips or shavings), volcanic cinder (used in Hawai=i because of its availability), and artificial media such as Oasis or rockwool.
SUMMARY
In summary, the advent of tissue-culture laboratories which produce massive quantities of reliably disease-resistant microcuttings has in many ways opened up many new possibilities for the Anthurium propagator, while presenting new challenges that must be met, as well.
Being able to order for delivery any quantity of Anthurium microcuttings for propagation will greatly facilitate reaching target propagation finish dates, and free the propagator of the expense and effort associated with maintaining large numbers of stock plants for propagules. However, the propagator, if he/she wishes to utilize tissue-culture technology for propagules, must be able to rise to the challenge of the rather intensive hardening-off process necessary for the microcutting propagules.
The consensus of opinion is that the majority of commercial propagation of Anthuriums is currently done by tissue culture. Therefore, for an Anthurium propagator to remain competitive in the Anthurium propagation industry, they will need to find a way of meeting the challenges of this brave new (Anthurium propagation) world.
