'DIGEST Department of Horticulture University of HawaII at Manoa

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1 Hawaii Cooperative Extension Service RO'lITIClTl.TI1'RE HITAHR Colle.e of Trollical Alrlculture and Human Re.ourcet U. S. Dellartment of Agriculture Coolleratlng 'DIGEST Department of Horticulture University of HawaII at Manoa In This Issue: FLOWER AND NURSERY INFORMATION No. 65, May TABLE OF CONTENTS Page Success in a Small Shop... 1 Plant Responses to Fonns of Nitrogen..., 1 Available Publications... 4 'Diamond Jubilee' Anthurium... 4 Coming Events 'Uniwai Prince' and 'Uniwai Princess', Two New Dendrobium Cut Flower Cultivars... '.' SUCCESS IN A SMALL SHOP Big does not necessarily mean success. Many small businesses can show a great profit if they are really good business men and women. Below are some of the major points in making a small business a success. 1. CATER to Customers. Please customers, roll.out the red carpet. Learn their likes and dislikes. Give extra service. Be an expert on your products. Build on existing customers. 2. BUILD an image. Use a steady and solid promotion. Don't wait for the other guy to do it. Build an image. Use your personality to encourage people to think of you in a favorable light.. A clean well lighted store helps create a favorable image. 3. ENCOURAGE teamwork. Customer satisfaction is only as good as your employees. Utilize your employees to help decide what to put on sale and how to display it. Teach all employees to know what to do; how to do it; when to do it. Praise employees in public. Correct in private. 4. PLAN ahead. Teamwork makes planning easy. Use 5-day weather forecast as a clue for planning special sales. Train an assistant. Put them in charge and take a day off. Look ahead-one year or five years. 5. LOOK for profit volume. Big sales volume does not necessarily mean high profit volume. Keep expenses in line. Make sure you list both fixed and variable expenses. Detennine your break-even pointuse it as a tool for control. Sales volume should be way above the point at which revenue and expenses balance. NY State Flower Industries Bulletin No. 138, March, 1982 PLANT RESPONSES TO FORMS OF NITROGEN An extensive problem encountered by anthurium growers on the island of Hawaii has been attributed in large part to ammonium toxicity. Symptoms exhibited by anthuriums affected by the syndrome include the following: small purple spots with necrotic centers on spathes, lack of color in spathes, water-soaking, collapse and necrosis of young leaves, severe chlorosis and stunting of new leaves, necrotic lesions on leaves and petioles, root tip necrosis, vascular browning in stems and roots, yellow appearance of spadix, suppressed rooting ability of cuttings, and reduction of plant vigor and flower yield. It is timely to review ammonium and nitrate nutrition in relation to fertilizer programs and crop responses in general. Nitrogen Forms When purchasing fertilizer, notice that the total N contained may come from three sources: (1) nitrate, (2) ammonium or (3) urea. Nitrate is highly mobile and easily leached, while ammonium tends to be immobile in soil. Urea is soluble and highly mobile but is quickly con':' verted to ammonium. COOPERATIVE EXTENSIO'N SERVICE 3050 MAILE WAY UNIVERSITY OF; HAWAII HONOLULU. HAWAII The University of HawaII ilt' Manoa. College of Tropical Agriculture ilnd Human Resources. Cooperative Extension Service and U. S. Department of Agriculture cooperating In presenting to the people Of HawaII programs and services to Its citizens without regard to race, color, national origin. or sex. It Is an equal opportunity employe,. I

2 Plants absorb organic N (e.g. urea) in small quantities. Most of the mineral nitrogen is absorbed in the ammonium and nitrate forms. Fertilizers such as ammonium sulfate and ammonium chloride have an acidifying effect on the soil. Uptake of ammonium by the plant tends to lower soil ph, while uptake of nitrate tends to raise it. Ammonium is converted to nitrate by micro-organisms, resulting in an acidifying effect. Plant Preferences for Nitrate and Ammonium Although the exact mechanisms underlying plant responses to the form of nitrogen fertilization may not be clear in many cases, defmite plant preferences have been demonstrated. Azalea gives better growth with' less chlorosis when receiving some ammonium rather than only nitrate nitrogen. Colgrove and Roberts at Oregon State demonstrated best growth with a 3: 1 ratio of ammonium and nitrate (4). Poinsettia, given a combination biweekly 2:3 ratio ammonium to nitrate fertilizer and biweekly 2: 13 ratio ammonium to nitrate fertilizer, were darker green than those given weekly 2: 13 or 0: I ammonium to nitrate fertilizer. Some cultivars tested showed no leaf injury with the higher ammonium source, but others showed varying levels of injury (3). Corn has been shown to grow more rapidly when ammonium is included in the fertilizer (15) rather than with ammonium or nitrate alone. Sunflower behaves similarly. In plants such as wheat, ryegrass, cotton, grain sorghum and coastal bermudagrass no preference for N form has been demonstrated. Nitrate sources of N are more expensive than ammonium sources. Many fertilizer manufacturers are increasing the percentage of ammonium in the formulations. Economically, it may be advantageous to add a percentage of ammonium to the total N in the fertilizer program, but the ratio of ammonium to nitrate can be too high. Plant Problems Associated with Ammonium Nutrition General symptoms of ammonium toxicity include foliar yellowing and/or necrosis; browning, necrosis and poor growth of roots; necrotic lesions on stems, and poor shoot growth. The following problems have implicated toxic responses to ammonium nutrition. Florida researchers, in a study of six producers, found that leatherleaf fern wilt was highly correlated with sources and ratios of fertilizers. 2 Specifically, producers who used fertilizer sources composed almost exclusively of urea and ammonium had the most severe wilt problem, while those using 25% nitrate nitrogen had the least. The data indicate that nitrogen source is implicated in the fern wilt problem, particularly during warm summer months accompanied by high rainfall (5). Mills reports that shorter fronds, a bronze cast to the foliage, vascular browning and burning of the young fronds are symptoms typical of ammonium toxicity in leatherleaf fern (12). Poinsettia leaves immediately below the bracts turn yellow with browning of the margins and premature leaf drop when fed a ratio of 2:3 ammonium to nitrate (3). With only an ammonium source of N, water uptake is severely restricted; severe leaf chlorosis, marginal necrosis, leaf drop and sometimes death of the plant occurs (2). Carnations respond with poorly developed brown roots, interveinal chlorosis of young leaves, wilt and eventual necrosis (16). Symptoms of nitrogen toxicity in roses are similar to high soluble salt symptoms, and their specific characteristics are often related to the accompanying anions or cations. Excessive rates of ammonium sulfate can reduce the ph and produce interveinal chlorosis which may look very similar to manganese or iron deficiency symptoms. New leaves can be bleached to a nearly white or pink blush color. Older leaves become marginally necrotic followed by total necrosis and abscission. Excessive ammonium nitrate can cause leaf necrosis similar in appearance to moisture or heat stress. Nitrogen toxicity is most likely to occur at extremes of soil moisture. Ammoniacal or nitrate forms of nitrogen may accumulate when the media is poorly drained. Compared with nitrate N, the ammoniacal form is toxic at fairly low concentrations ( 17). The effects of form and amount of nitrogen on barley, wheat and rice have been researched in Japan. Roots were extremely damaged and grain yields reduced when rice plants were grown in culture solutions containing more than 30 ppm of ammonium nitrogen. Nitrate nitrogen, however, was not toxic even at 50 ppm. Results showed that the adverse effects of ammonium nitrogen could be minimized either by application of high phosphate levels or by replacing part of the ammonium with nitrate N. Ammonium-induced root injury once incurred, and especially in advanced stages, was very difficult or impossible to recover (8). Tomato develops nutritional leaf roll, an...

3 N Sources in Some Commonly Used Fertilizers N p K NH4 N03 Urea Slow Release Osmocote % 40% MagAmp % Soluble Foliar % 21% Foliar % 17% 43% Peters % 28% 52% Peters % 53% 25% Grow More % 59% Granular Lesco + Iron % 88% HydroPrills % 42% Turf Supreme % upwardly oriented roll of leaves, when fertilized with only ammonium -N or urea (15). Tomato also develops severe necrotic lesions on the stems. The lesions flrst appear as slightly elongated depressions on the stem and become brown and pitted. They develop quickly and can cover the entire stem surface and petioles (9). Potassium in adequate amoun!s is effective in preventing stem lesion formation on tomato by promoting better utilization of the applied. (2) ammonium. Potassium greatly influences several aspects of N metabolism. Reports indicate that potassium has a role in protein synthesis and proteolysis occurs when potassium is deficient (10). Bean, cucumber and pea on an ammonium fertilizer program show symptoms of immediate restriction in growth, wilt, marginal necrosis, interveinal chlorosis of terminal leaves, poorly developed and brown roots, death of the entire plant. Sweet com responds with restricted growth, wilt, very dark green leaves with no evidence of necrosis (11). Physiology of Ammonium Toxicity In ammonium toxicity chloroplasts are severely disrupted and photosynthetic capabilities are impaired (1, 13). Carbohydrate reserves are directed to incorporation of free ammonium ions into nontoxic forms. This occurs at the expense of other compounds necessary for cellular metabolism and can result in carbohydrate depletion. Plants well supplied with carbohydrate are better able to use ammonium N than are energy-starved plants. Thus seedlings and germinating seeds are very sensitive to ammonium toxicity. Ammonium. assimilation occurs in the roots. It has been found that carbohydrate availability in the roots and the maintenance of a neutral ph 3 in the root environment increase plant tolerance to ammonium toxicity. With high ammonium fertilization, secondary nutrient problems such as calcium or potassium deficiency may occur due to an inhibitory effect on uptake. Preventive Measures (1) Know your fertilizer. What are the sources (3) ofn? Know your crop. For example: Poinsettia-No more than 50% of total N should be ammonium (7) Foliage crops-25% of total N should be in nitrate form (6) Leatherleaf Fern-40-60% of total N should be in nitrate form. Omit urea entirely (5). Know general symptoms of ammonium toxicity Poor roots-necrotic root tips, brown and unhealthy Decreased total plant growth Necrotic lesions on stem and leaves, chlorosis (4) Keep soil ph at optimum levels Have soil tested pre-plant; if using artificial media, test batch for quality control. Lime as recommended following CaC03: dolomite ratio recommendation References 1. Barker, A.V. & H.A. Mills Ammonium and nitrate nutrition of horticultural crops. Hort. Revs. 2: Boodley, J.W Nitrogen fertilizers and their influence on growth of poinsettias. Florists' Review 147:26-27, Byrne, T.G. & R.F. Hasek Poinsettia leaf injury associated with NH4 + fertilization and low soil ph. Florists'

4 Review, 165:28-29, Colgrove, M.S. & A.D. Roberts Growth of the azalea as influenced by ammonium and nitrate nitrogen. Proc. Amer. Soc. Hort. Sci. 68: Conover, C.A., R.T. Poole & L.L. Loadholtz Update on leatherleaf fern wilt. ARC-A Research Report RH pp. 6. Conover, C.A. & R.T. Poole Basic fertilization guide for acclimatized foliage plants. Florists' Review 168: 10-11, Ecke, P. Jr. (edit.) The Poinsettia Manual. O.A. Matkin. Soil & Plant Lab. Calif. 8. Imai, H The harmful effects of ammonium nitrogen on crop roots. Proc. Inti. Seminar on Soil Environment and Fertility Management in Intensive Agric. Tokyo. Soc. of the Sci. of Soil & Manure. 9. Maynard, D.N., A.V. Barker & W.H. Lachman Ammonium-induced stem and leaf lesions of tomato plants. Proc. Amer. Soc. Hort. Sci. 88: Maynard, D.N., A.V. Barker & W. H. Lachman Influence of potassium on the utilization of ammonium by tomato plants. Proc. Amer. Soc. Hort. Sci. 92: Maynard, D.N. & A.V. Barker Studies on the tolerance of plants to ammonium nutrition. J. Amer. Soc. Hort. Sci. 94: Mills, Harry A (personal communication) 13. Mills, H.A. & J.B. Jones, Jr Nutrient deficiencies and toxicities in plants: Nitrogen. J. Plant Nutrition 1: Schrader, L.E., D. Domska, P.E. Jung, Jr. & L.A. Peterson Uptake and assimilation of ammonium N and nitrate N and their influence on the growth of corn (Zea mays L.) Agron. J. 64: Volk, G.M Effect of urea nitrogen on nutritional leaf roll of tomatoes. Proc. Fla. State Hort. Soc. 71 : White, J.W Interaction of nitrogenous fertilizers and steam on soil chemicals and carnation growth. J. Amer. Soc. Hort. Sci. 92: White, J.W. Greenhouse Roses, Diagnosis and Remedy of Nutritional Disorders. Roses Inc. Ruth. Y. Iwata, Assistant Horticulture Specialist Kenneth W. Leonhardt, Associate Horticulture Specialist 4 AVAILABLE PUBLICATIONS Storage of Vanda Orchids Research Series 008, Effects of Static Controlled Atmosphere and Reduced Pressure Storage on Fading of Vanda Miss Joaquin Flowers by E.K. Akamine and T. Goo, presents results of laboratory experiments on one of the major problems in the overseas shipment of Vanda Miss J aoquin orchid flowers from Hawaii. Premature fading can pe reduced or controlled by short static CA or reduced pressure storage. Insect Control Guide HITAHR Brief No. 012, 1982 Guide for Chemical Control of Insect and Mite Pests of Commercial Foliage Plants in Hawaii by Ronald F.L. Mau, presents current information on the chemicals available for insect control on foliage plants. Copies of these publications may be obtained by contacting your local County Extension Office or by writing to the Publication and Information Office, Rm. 107, Krauss Hall, 2500 Dole St., University of Hawaii, Honolulu, HI 'DIAMOND JUBILEE' ANTHURIUM An attractive, medium-sized, light-orange obake anthurium selection (UH517) has been named 'Diamond Jubilee' and is being released to the anthurium industry in conjunction with the 75th Anniversary Celebration of the University of Hawaii. This new cultivar originated from a cross made on April 23, 1969 between 'Sunburst' (orange) and 'Manoa Mist' (white). The seedling selection was designated UH517 and placed under observation and evaluation for a few years at Manoa. It was later advance tested at the Branch Experiment Station at Waiakea and with cooperating growers at Pahoa and Waiakea. The fme performance of this selection in these tests has dictated the naming and release for commercial cropping purposes. Outstanding features of this new cultivar are; exceptionally high yields of about 7.7 flowers per plant per year, resistance to anthracnose, and medium-sized light orange obake flowers, a type not now available to the industry. This new cultivar is a welcome addition to the standard color types being produced by the industry in Hawaii.. The description of this new cultivar follows: Spathe Color Light orange (RHS Colour

5 Size and Shape Spadix Color Size and Shape Anthracnose Flower Stem Yield Foliage Blade Petiole Chart 41C), Lobes green (RHS Colour Chart l37b). 6 inches long, 6Y2 inches wide; lobes not fused. Yellow changing to white with maturity. 3 inches long, 12 inch thick, reclinmg. Resistant. 28 inches long, ~ inch thick; slender and straight. 7.7 flowers per plant per year. 12 inches long, 6Yz inches wide. 16 inches long. H. Kamemoto, Horticulturist J.T. Kunisaki, Assistant Horticulturist T. Higaki, Horticulturist M. Aragaki, Plant Pathologist COMING EVENTS Flower Show A major flower show will be held at the Hemmeter Center in Waikiki on June 10-13, The theme of the four day event is "In the Good Ole' Summertime". Landscape Contractors The California Landscape Contractors Association's summer tri-board is scheduled for Merriott's Great America, Santa Clara, CA July 8- II, (916) Canada Trade Show July is the date for the Western Canada Horticultural Trade Show in the Food Building, Pacific National Exhibition, Vancouver, B.C. Contact Joe F. Croeca (604) AAN to Meet in Hawaii Plans are underway for the American Association of Nurserymen to hold their 107th annual convention in Honolulu at the Sheraton-Waikiki. Hotel on July 16-18, They expect over 2,000 nurserymen from throughout the United States to register for this convention. The Mailorder Nurserymen's Association and the California Association of Nur,serymen will also be meeting in Hawaii at the same time. HAN Conference The Hawaii Association of Nurserymen annual conference will be held July 20 at the Sheraton-Waikiki Hotel in conjunction with the AAN convention. HAN will also hold its annual Trade Show at the Sheraton Hotel July Contact HAN, P.O. Box 293, Honolulu, HI (808) SAF Convention The annual convention of the Society of American Florist will be held July at the Fontainbleau Hotel, Miami, FL. Contact Darryl MCEwen (800) Farwest Show The Farwest Show and the Ornamentals Northwest Seminars are scheduled at the Memorial Coliseum in Portland, OR., August 26-30, Contact Dan Bornhost (503) International Horticultural Congress The XXIst International Horticultural Congress will be held in Hamburg, Germany from August 29 to September 4, In addition to contributed papers on various horticultural topics, Floriculture and Ornamental Tours are being organized to Stuttgart and Amersterdam. Plant Propagators The Western Region of the International Plant Propagators' Society is developing plans for their annual meeting to be held in Hawaii, October 5-9, The program will be held on Kauai and Oahu and include tours to places of horticultural interest. Contact Phil Parvin (808)

6 Pacific Hort Show The Pacific Horticultural Trade Show sponsored by the California Association of Nurserymen will be held at the Los Angeles Convention Center, October 13-15, Contact: Richard C. Staples (916) Interior Plantscapes The 4th annual conference and trade show of the Interior Plantscape Association has been set for October 25-27, 1982 in Portland, Ore., at the Portland Marriott Hotel. Contact: Interior Plantscape Association, 1800 Sunrise Valley Drive, Reston, VA (703) Foliage World The Foliage World and New Concepts Trade Show will be held at the Sheraton Twin Towers in Orlando, Florida, January 18-20, Foliage Short Course The National Tropical Foliage Short Course has been scheduled for January 20-22, 1983 at the Howard Johnson's, Kirkman Road in Orlando, Florida. AAN Convention Queen Elizabeth Hotel, Montreal, Canada,. July 16-20, Tele/lora National Conference Chicago, IL, July 17-20, SAF Annual Convention Western Hotel, Seattle, WA, July 20-23, FTD Annual Convention Honolulu, HI, August 18-25, 'UNIW AI PRINCE' AND 'UNIWAI PRINCESS', TWO NEW DENDROBIUM CUT FLOWER CULTIVARS 'Uniwai Prince' (UHS03) and 'Uniwai Princess' (U1:iS07) are the fourth and fifth seedpropagated Dendrobium cut flower cultivars released by the University of Hawaii through the Dendrobium Growers Association. Both are tetraploid or amphidiploid Dendrobium J aquelyn Thomas hybrids each possessing two sets of chromosomes of the parental species, Dendrobium phalaenopsis and Dendrobium gouldii. Flowers of Uniwai Prince are purple-violet (RHS Colour Chart 80A), and those of Uniwai Princess are slightly lighter purple-violet (RRS Colour Chart 80B). The former is a cross between the tetraploid Jaquelyn Thomas '0580-3' and the dark purple, tetraploid J aquelyn Thomas ' ', while the latter is a cross between Table 1. Monthly spray yields of 'Uniwai Prince' (UHS03) and 'Uniwai Princess' (UHS07) (Total of 22 plants per cultivar) TOTAL Uniwai Uniwai Uniwai Uniwai Uniwai Uniwai Month Prince Princess Prince Princess Prince Princess January February March April May June July A 1 1gust IS September IS 30 October November December TOTAL Ave. yield per plant

7 Table 2. Characteristics of 'Uniwai Prince' and 'Uniwai Princess' Characteristics Length of sprays (inches) Length of scape (inches) Size of flowers-across (inches) No. flowers per spray Vaselife (half life in days) Percent bud drop Heig.l1t of pseudobulb-feb (inches) 'Uniwai Prince' 21% 7~ 2~ ~ 'Uniwai Princess' 23 6% 2~ H. Kamemoto, Horticulturist J. MCConnell, Research Assistant the white, inbred, tetraploid Jaquelyn Thomas 'K ' and the dark purple, tetraploid Jaque1yn Thomas 'DI68-12'. Both of these new cultivars complement the three cultivars released earlier: 'Uniwai Blush' (pink blush), 'Uniwai Supreme' (two-toned lavender) and 'Uniwai Pearl' (white). Table 1 shows monthly yields of both cultivars for 1980 and Although only two years' data are available, yields and seasonality of older plants are expected to be similar to those of the cultivars released earlier. Characteristics of both cultivars are shown in Table 2. Sprays of Uniwai Princess are slightly longer than those of Uniwai Prince, and number of flowers per spray are correspondingly more numerous. Vaselife and percent bud drop are about equal. Plants of Uniwai Prince are much shorter and consequently more.desirable than those of Uniwai Princess. Editor's Note: While this is not related to horticulture, it should be of interest to all human beings. This article was taken from the Newsletter of the Tropical Region, ASHS, No. 109, January Will we ever be free of those pesky flies? We have been informed that two chemists from the University of Toronto have invented an artificial hormone that stimulates the sexual activ~~ of male domestic flies to the point that they quickly wear themselves out. The poor males develop a voracious sexual appetite and begin to mate indiscriminately with already fertilized female flies and even with other males. Finally, after about two weeks they die of exhaustion. A colony of two hundred females was wiped out in three generations with the use of this hormone. Luckily, the hormone does not affect humans or other animals, and can be easily and cheaply produced. It will be particularly useful in the tropics. FOOD FOR mought The trouble with some people is that they won't admit their faults. I'd admit mine-if I had any. Don't bug me about my mistakes. Look at all the thought that went into them. When in danger, run in circles; When in doubt, scream; When cornered, SMILE. NOTE: The use o{ trade names is {or the convenience o{ readers oo1y and does not constitute an endorsement o{ these products by the University o{ Hawaii, the Cooege o{ Tropical Agriculture and Human Resources, the Hawaii Cooperative Extension Service, and their employees. Extension Specialist in Horticulture 7