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• Diseases
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• Pests
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Status

INDUSTRY

The Statistics of Hawaiian Agriculture, published by the Agricultural Reporting Service, Department of Agriculture (DOA), shows that the total worth of sales for the carnation industry in Hawaii was $1,331,000 in 1984. This amount was generated by 32 commercial farms from the sale of 91,000 dozens of cut stems and 33,600,000 flower heads (blooms for lei-making).

LOCATION

The industry is concentrated on the island of Maui, where more than 95% of the total worth of sales for lei heads and 74% of cut stems were generated. The rest of the industry is located on the Big Island of Hawaii.

CATEGORIES

The carnation industry in Hawaii may be divided into two categories: Lei Heads and Cut Stems. Lei head varieties are the standard cut stem varieties grown on the mainland. Some of the newer "minature" spray carnations are also being grown for lei heads. Cut stem varieties may be similar to lei head varieties but are disbudded to a single flower per stem, and each calyx may have to be banded to prevent splitting. On Maui, the majority of cut stem carnation varieties are of the spray or miniature types, with a minority of the standard varieties grown as cut stems. Both lei heads and cut stem production may be found in both the fields and greenhouses.

VALUE

The value of sales from lei heads was $1,112,000, a reduction of 14.7% from that for 1983. On the other hand, the value of sales from cut stems increased from $179,000 in 1983 to $219,000 in 1984, an increase of 22%. Statistics for lei heads from 1980 through 1984 indicate that there is no definite trend in the volume of marketings, but that for cut stems showed increases during the past two reporting years (statistics for 1985 are not yet available) after a very low production year in 1982 caused by weather related problems.

COMPETITION

During the summer, less expensive flowers (plumeria, tuberose, vanda) compete with the higher priced carnation for use in leis. However, it is recognized that the use of various scented flowers enhances the acceptability of carnations in leis. The longer shelf life of carnation leis is considered a real advantage.

IMPORTS

Although the sale of leis is related to the influx of visitors throughout the year, there is a peak demand period for carnation leis during graduation time in late May to early June, when imports are necessary. At other times, availability of local products determine the amount imported, since local carnations are fresher and last longer than the imported carnations.

Practices

Hawaii's carnation industry could be considered unique because of its almost exclusive reliance on open-field cultivation of lei head production. However, there are specific problems arising from this uniqueness of production and flower use:

1. First and second flower croppings can be closely timed for peak sales, but subsequent production peaks and valleys are less clearcut and there could be low levels of sustained production.

2. Carnation flowering tends to be heaviest during the summer months when the demands are lowest; therefore, lei makers must import flowers when local growers cannot meet demands during periods of high demand.

3. Nutritional requirements for multi-flowered production may be different than that for the traditional, single-stem cut flower production. Current fertilization practices are based on mainland recommendations for cut flower production.

   
   

Nutrition is one area of primary focus in increasing flower productivity and quality:

1. Phosphorus application is a problem because its need is coupled to the plant's growth and reproductive status.

2. Application of nitrogen and potassium is less of a problem because the soluble nature of the fertilizer sources makes them easier to apply when needed. Still, the timing of the application with respect to flowering deserves attention.

3. Some resistance to fusarium has been attributed to fertilization with higher levels of calcium, and perhaps potassium. The growers need to know optimum levels.

4. A physiological disorder, carnation calyx tip dieback, may be stress-related or have a nutritional basis. It occurs primarily in the spring and results in lost sales. Work remains to identify the cause, although low potassium and calcium levels in the calyx have been associated with expression of the problem.

5. Carnations are grown on diverse soil types in Hawaii. As a result, recommendations for fertilization may not be generally applicable.

   
   

The use of continuous emitter irrigation systems affords a method for the application of some nutrients and pesticides in the irrigation water:

1. Water quality affects the effective utilization of these systems as unfiltered water carries particles and algae which clog emitters.

2. Certain pesticides may not be registered for application by such systems.

3. Irrigation requirements vary with method of culture; whether the crop is produced under cover or in the open field.

   
   

New carnation cultivars have been introduced in Europe and the mainland U.S., and these should be tested in Hawaii:

1. fusarium resistant cultivars and miniature and spray-type carnations, which are becoming popular, should be tested for economic traits.

2. New flower colors and petal types should be evaluated by the industry for suitability as lei flowers and new carnations should be evaluated for potential as cut flowers.

Diseases

Many diseases affect carnations in Hawaii, and their proper control could be the most important cultural practice facing the growers. Losses from diseases industry-wide normally run about 20%. Among the most commonly found diseases are:

1. Alternaria - flower blight, leaf spot and branch rot;

2. Botrytis flower blight;

3. Fusarium oxysporum - wilted branches frequently one-sided at first;

4. Fusarium roseum - stem rot, roots, base, stem;

5. Pythium root rots;

6. Rhizoctonia - stem and root rots;

7. Puccinia - rust pustules of powdery brown spores

   
   

NEMATODES

Although nematodes are widely distributed throughout carnation producing areas, the existing control measures are doubtful.

CHEMICALS

Although there are chemicals registered for these diseases, their high costs, short periods of effectiveness, and possible buildup of resistant organisms make the effective control of diseases a major production problem.

VAPAM

Vapam, applied at 100 gallons per acre to moist soil previous to manuring, is an effective fumigant for the control of most carnation soil-borne pathogens, except nematodes. A water seal 6-8" in depth must be applied immediately after the chemical is broadcasted on the soil surface. Control is enhanced by removal of previous carnation crop residues before soil preparation for chemical treatment.

In tests conducted by the CTAHR, the variability in control of soil fungal pathogens with Vapam has been correlated to soil moisture, manner of chemical application, and depth of water seal use. Fields showing high populations of Fusarium sp. and Rhizoctonia sp. before and after treatment, were fumigated while the soil was dry and the water seal applied did not carry the chemical down to the 6-8" level necessary for effective control. Poor control of soil-borne pathogens was evident in fields where previous carnation plant residues were not removed or manuring was applied before soil fumigation. Nematode control with Vapam has been difficult to assess because very few fields on Maui have shown parasitic nematode populations above damage thresholds.

Fusarium roseum f.s. graminearum, the cause of carnation stalk rot, has been found in non-fumigated carnation soils in populations ranging from 0 - 5000 colony forming units (cfu) per gram of soil. The fumigant Telone does not control this pathogen.

Diseased carnation plants collected from different Maui farms have yielded 3 distinct pathogenic types of Rhizpctonia solani belonging to 3 anastomosis groups: AG 2-1, AG 2-2 and AG 4.

Preliminary pathogenicity tests conducted at Manoa (Oahu) with AG 2-1 using varieties Peterson Red Sim and Improved White Sim showed Peterson Red Sim to be highly susceptible and Improved White Sim highly resistant. Variety tests done at the Kula Branch Station on Maui, using 7 standard varieties (Peterson Red Sim, Improved White Sim, Scania 3C, Atlantis, Portrait, Red Diamond, and S. Arthur Sim), and two miniature varieties (Elegance and Exquisite Select) have shown all to be susceptible to R. solani AG 2-1. Elegance was the most susceptible showing 100% mortality 17 weeks after inoculation and Atlantis and Red Diamond and most resistant with 60% mortality.

All varieties were highly resistant to R. solani AG 2-2 and AG 4. Rhizoctonia solani-like fungi (Ceratobasidium spp.) were not pathogenic to carnations.

Hawaii Pesticide Information Retrieval System, CTAHR

ROTATION

Due to the buildup of diseases in the soil, rotation of fields are advisable. However, growers find this practice to be impractical because of the limited area they have for farming.

The publication of a disease guide with color photos has been estimated to cost $10,000 and, because of lack of resources, work on a much needed integrated disease control program has not yet been initiated.

Labor

There are no unique labor problems for carnation growers. Adequate labor is available if the price paid is sufficiently high.

The cost of labor represents a very large percentage of the gross sales.

Workers are concerned about pesticides that are used in carnation production.

Land

Land between 2,500 and 4,000 feet in elevation is suitable for the year-round production of carnations. However, the availability and cost of land pose problems for new growers.

Water supply must be considered in land selection for carnation production.

Lei flower carnation growers can gross about $50,000 per acre. They normally net about 25-50% of the gross. approximately 23 growers on Maui produce $1,227,000 worth of carnations annually.

Pests

Hawaii's climate permits rapid buildups of aphids, bud mites, cutworms, thrips and mice populations in dense field plantings.

Losses due to insect, mite and mice damage are estimated at 15-20% per year for the past 5 years.

Registered chemicals for insect control are available, but some are phytotoxic to certain cultivars. Many chemicals registered for carnations were intended for use in greenhouses, but Hawaii's carnations are predominantly field grown.

Growers are concerned about the high cost of insecticides and about the dangers of using pesticides. Growers want tests conducted to see if dosages of insecticides could be decreased.

Insects and other pests--carnation, Knowledge Master, CTAHR
Hawaii Pesticide Information Retrieval System, CTAHR

Water

Greenhouse and field-grown stock require irrigation systems for reliable production.

DROUGHT

Certain areas on the Big Island and Kula on Maui are more subject to droughts than other flower-producing areas. Current value of the industry is $1,331,000. During periods of droughts lasting 2-3 months, irrigation water may become unavailable. This could reduce the income of the industry by 50% over a period of 6 months.

TRICKLE IRRIGATION

Advances in trickle irrigation have benefited producers in drought-prone areas. Although water quality generally presents no problems in Hawaii to cut flower producers, continuous emitter systems may develop clogging of the emitter by particles and algae in the water.

KULA AGRICULTURAL PARK

Upon completion of the new irrigation system for the Kula Agricultural Park, no further plans for additional agricultural water exist for the immediate future, even though the volume of water from the Agricultural Park is considered too low for good carnation production. There are also no plans at the present for dual water systems, one for urban use and the other for agricultural use. Higher priorities go toward meeting federal standards for clean water.

The lack of resources has prevented work on the design for an efficient irrigation system that would include considerations for fertilization, pest control, and water management.

Weed

Controlling weeds in carnation fields is a very important task for growers because of their year-round effect on soil nutrients. In addition, many weeds are alternate hosts for several disease and insect pests of carnations, thereby compounding other cultural problems.

The development of effective pre- and post-emergence weed control programs is in progress with other crops, but the degree of phytotoxicity on carnations has not been determined. This work is being done by the CTAHR.

More information is needed on effective chemicals to control chickweed, various legumes, swine cress, and vetch.

Hawaii Pesticide Information Retrieval System, CTAHR

Varieties

Cut Stem

Varieties used are both the standard greenhouse types as well as the newer miniature/spray varieties.

The standard lei head variety in Hawaii is Peterson Red, which is an older mainland-type still favored here for its disease resistance. Greenhouse varieties include Scania Red, Scania 3C and CSU Red. These are disease susceptible for field production. Improved White Sim is a popular white variety, while the varigated types include Red Diamond and Peppermint Lace. Nora is grown for cut stems and Pink Ice for lei head for the pink colored carnation trade.

Lei Head

Standard greenhouse carnation varieties (standard and miniatures) are grown.

Lei head varieties are the standard cut stem varieties grown on the mainland. Some of the newer "minature" spray carnations are also being grown for lei heads.

On Maui, the majority of cut stem carnation varieties are of spray or miniature types, with a minority of the standard varieties grown as cut stems.

Cut Stem

Total time required for harvesting, grading, and bunching for shipment for the spray/miniature types is 10 bunches per hour with 10 to 12 stems per bunch. On the mainland, a "bunch" must have 35 to 40 flowers or buds showing color that will open. This might only require 8 stems. Some growers harvest, grade, and bunch in the field; others harvest and take to the shed for grading and bunching. Carnations should be "conditioned" in floral preservatives and chilled for longest shelf life.

On Maui, a popular shipping carton is the dairy box in which empty milk cartons are brought in. This is approximately 8" by 18" in size. Shipping costs represent approximately 20% of the value of miniature carnations.

Lei Head

Some growers pick, count, grade and pack in the field. Others harvest and bring the flowers to the shed where they are cleaned, sorted, graded, and packed. Boxes are then chilled. An average of 1,500 heads can be harvested, graded, and packed per hour. Two hundred fifty to three hundred per box are common. Some boxes contain 500 to 700 heads.

Transportation

Flowers are shipped to Honolulu via inter-island air carriers.

Air freight represents 6 to 15% of the flower prices. Minimum freight should be 10 boxes at 19 cents per pound. If growers combine shipments, the bulk rate may drop to 10 cents per pound, with 50 to 80 flowers per pound. Winter flowers are heavier, due to their larger size and higher moisture content.