...Return to lfon Main...

Landscape, Floriculture, and Ornamentals News

Date Last Edited:  08/10/2001

Hawaii Cooperative Extension Service

No. 4, November, 1998


David Hensley, dhensley@hawaii.edu
Kenneth Leonhardt, leonhard@hawaii.edu
CTAHR Extension Horticulture Specialists

Kent Kobayashi, kentko@hawaii.edu
Dept. of Horticulture, CTAHR, Univ. of Hawaii

Contracts that Make $ense for Property Managers

David Hensley, dhensley@hawaii.edu
Extension Landscape Specialist
Department of Horticulture, CTAHR

Paying a low price for something does not always mean it is a bargain. This is equally true for landscape services. When hiring outside contractors to provide landscape maintenance or other specialty services,

  • do not sign a contract on the basis of the bottom line price alone.
  • compare costs of individual services,
  • compare qualifications of all bidders, and
  • negotiate the final contract price to get the best qualify work at the most competitive price.

Compare the Costs

It is easier to compare the cost of services from several contractors when all pricing information is quoted in the same format or based on uniform specifications. At the very least

  • request that the services or program be priced individually for the month or visit.

  • compare bye prices by making a side by side comparison form and listing the itemized costs of the services, such as mowing, edging, fertilizing, pruning, etc.

Any major discrepancies in pricing between contractors can be pinpointed immediately.

Selecting the Right Contractor

Price is not the only criterion for selecting a contractor. Just because a contractor has supplied the manager with competitive unit costs for all the work specified does not mean he/she can complete that work or provide the quality and service expected. Maintenance contractors are not created equal. Investigate the two or three most competitive contractors. Consider:

  • References. What similar sites does the firm maintain? How long? How does the present manager feel about the service and work?

  • Qualified staff. Is the contractor's staff horticulturally and technically trained to adequately perform the maintenance work?

  • Operating capacity. Is the contractor able to add this site to the work load with the current level of staff? If not, what adjustments will be made?

  • Available equipment. Does the contractors have the right and enough equipment to provide the needed services? Does he/she have back-up equipment when (not if) breakdowns occur?

  • Office visit. Will the contractor allow a visit to his/her office or staging area? Remember, landscape maintenance is a serice- and labor-intensive industry. Do not expect an office on Bishop Square; expect a working shop and equipment storage. Upon inspection, does the office, yard, and equipment create a sense of confidence in the firm's ability to perform the work requested?

Negotiating the Contract Price

Once costs have been compared and the qualifications have been reviewed, there is an opportunity for some final negotiations with the preferred contractor. Remember that in these times, there may not be much "fat" in the bid. Demands may reduce the price somewhat, but the quality may suffer if requirements to ge the job are unreasonable.

If the cost is too high, look at the services requested. Does the curb really need to be edged every mowing, or can it be edged every other mowing? Reducing the service required is the best way to bring costs into line with budget.

Top of Page

New Variety of Sweet Corn Released by CTAHR

Dr. Jim Brewbaker, Prof. of Horticulture, CTAHR, (brewbake@hawaii.edu) has announced the released of an improved variety of Hawaiian Supersweet #9. The new variety, called #9 SILVER, is the result of over 20 years of research. According to Dr. Brewbaker, it has been a favorite among taste panels and guests to Waimanalo Field Days.

  • The kernels of #9 SILVER are silvery white, supersweet, and very tender.

  • The new variety is resistant to Hawaii's insects and diseases, showing a notably high resistance to Hawaii's serious maize mosaic virus.

  • #9 SILVER is an open-pollinated variety that ripens in about 10 weeks.

  • Its yield exceeded all Mainland varieties to which it was compared.

Seeds may be obtained from Richard Sakuoka, Seed Specialist at CTAHR, (rsakuoka@hawaii.edu) at the Department of Horticulture Seed Program, 3190 Maile Way, St. John 112, Honolulu, HI 96822. The phone number is (808) 956-7890, or FAX (808) 956-3894.

Seed Program, CTAHR (buy fruit and vegetable seeds)

UH campus map showing the location of St. John.

Top of Page

Primo on St. Augustinegrass

David Hensley, dhensley@hawaii.edu
Landscape Extension Specialist
Dept. of Horticulture, CTAHR

Primo®, a plant growth regulator used widely on golf courses, is labeled for St. Augustinegrass, according to Dr. John Cisar, University of Florida (jlci@ufl.edu). Primo, according to Dr. Cisar, is used on St. Augustinegrass in Florida to suppress growth, but can also lower turf quality and discolor turf somewhat (at least initially). If you can accept that, then spray 0.25 oz of Primo/1000 sq ft, the rate that causes the least amount of discoloration. A higher rate of 0.5 oz is labeled for 'Floratam' and 0.38 oz for 'Raleigh' St. Augustinegrass. Do not exceed 0.79 oz/1000 sq ft/year.

Be careful to apply Primo to healthy, vigorously growing, non-weed infested, and non-stressed turf. Hot weather is a caution as well. Uniform and non-overlapped coverage is essential to avoid discoloration and a uniform growth effect. If you are not absolutely comfortable with precision spraying, call in a professional. Applications can be made about every 4-6 weeks, depending on the response of the turf and your acceptance of discoloration.

One more note: weeds are not readily suppressed by Primo. By applying Primo you could have more weed competition, which may ultimately affect the quality and quantity of the St. Augustinegrass. Before applying any pesticide or herbicides, read and understand the label.

An evaluation of several rates of Primo on common St. Augustinegrass (Stenotaphrum secundatum (Walt) Kuntze). Texas A&M University.

Primo®, Novartis Crop Protection, Inc.

St. Augustine, extension publication, CTAHR

St. Augustine growth responses to various plant growth retardents. University of Florida.

Top of Page

Pest Management Techniques for Diseases of Hibiscus and Other Ornamentals

Jay Deputy, deputy@hawaii.edu
Education Specialist
Dept. of Horticulture, CTAHR

Producers of hibiscus and other ornamentals face the challenge of producing a variety of blemish-free crops. Fortunately, under the special conditions of greenhouse/shadehouse production, there is a wide range of management techniques available for both fungal and bacterial disease control.

Exclusion by quarantine
One of the most effective strategies for preventing a pathogen from infecting plants is exclusion by quarantine. Growers should implement their own quarantine measures to safeguard against introduction of a pathogen.

When new plants are purchased, they can be maintained in separate structures until their health is confirmed. It is especially important to maintain stock plants under quarantine to protect them from infections, since contaminated stock plants produce only contaminated cuttings.

Good sanitation practices
Good sanitation practices are also very effective. Pathogens may be introduced in plant propagules, potting media, equipment, insects, weeds, soil under benches and in walkways, and sometimes irrigation water.

The specific control method which will be most effective depends upon the source of the pathogen.

  1. Eliminating weeds and crop debris, removing diseased plants, and occasionally removal of diseased leaves, collectively create an environment unfavorable to pathogen spread and favorable to early disease detection.

  2. Benches should be cleaned and sanitized between crops, and the use of clean pots, flats, and tools is very important.

    If benches are cleaned between crops, placing new plants in contaminated pots or flats will negate the benefits of all other control strategies.

    The growing media is an integral part of all plant production systems for greenhouse ornamentals.

  3. Media must be mixed and held in areas which are not contaminated with native soil.

  4. The media should be covered with a water-proof tarp to reduce chances of contamination with pests such as insects, weeds, and plant pathogens as well as exposure to rainfall.

  5. Growing plants on raised benches removes them from the ground, which is a very common and extremely important source of infection. Many root and stem rot pathogens are present in native soil and are able to move into beds and pots placed on the ground.

  • Proper irrigation practices
    Proper irrigation practices are also an important part of disease control. Water management encompasses the water needs of the crop plant as well as the delivery method and humidity.

    Amount of water
    Water stress, through either too much or too little water, can result in more severe disease development. This is often seen in root rot diseases caused by fungi, which are more serious when plants are over-watered. Roots die when kept too wet due to oxygen starvation. Once the pathogen gains entrance through dead roots, it can spread throughout the root system.

    The potting medium should not retain excessive water for long periods of time since even a small amount of water can be too much. Irrigation management of plants in a heavy potting medium is even more critical because it holds more water and has fewer large pores for air, an ideal condition for root disease.

    Water on foliage
    One of the most important considerations in irrigation management is the elimination of standing water on plant foliage. The method of delivering water to the plants is therefore an important consideration for reducing both the development and spread of diseases.

    Water systems which cause leaves to stay wet for long periods of time or cause splashing are ideal ways to spread pathogens and increase disease severity. Rapid leaf drying greatly reduces disease severity since many fungal spores and bacteria cannot infect leaves without a minimum period of free water on the leaves.

    It is even better to use a method of irrigation which does not delivery water to the leaf surface at all. Systems such as drip irrigation, ebb and flow systems, and capillary mats are used for a variety of plants to minimize pathogen spread and disease development.

  • Biological control agents
    The potential for the use of biological control agents in greenhouse ornamentals is relatively high for insects and mites, but not for many pathogens.

    1. Unfortunately, the zero tolerance level for damage on the ornamental product would suggest that use of biological control may be confined to stock areas or to early stages of crop production where minimal damage may be acceptable.

    2. A major problem with implementing biological control in the greenhouse is the common use of a multitude of pesticides which can eliminate non-target biological control agents as effectively as the target pest.

    Biological control is not currently a method which can be used to control most diseases of greenhouse ornamentals. Although some examples of successful biological control of a plant disease are available, they have not been readily employed commercially since they are specific to a particular disease on a relatively small group of crops.

  • Pathogen-free blocks of mother or stock plants
    Establishment of pathogen-free blocks of mother or stock plants is an important step toward eliminating the introduction of contaminated cuttings. Most potted flowering plants are produced from cuttings of tips or stems which can be contaminated with a wide variety of fungi, bacteria, and viruses. Utilization of pre-plant dips to control diseases is usually ineffective for a variety of reasons.

    1. Probably the most significant factor is the chemicals which are available are not eradicants, and the degree of control is less than 100% even under ideal conditions.

    2. In addition, the act of immersing cuttings in a water solution creates ideal conditions for pathogen spread. Even a very low incidence of contamination or infection in dipped cuttings can result in contamination of all cuttings.

    3. Finally, immersing cuttings with latent infections into water can trigger the development of many diseases.

    Tissue culture and quarantine
    Pathogen-free plant propagules are available for some plants from tissue-culture. While some growers utilize pathogen-free tissue-cultured plantlets as a propagative material, others use these plants to establish blocks of stock plants to produce cuttings. These blocks must be maintained under quarantine type conditions to keep them as free of plant pathogens as possible. Stock plantings should have a limited life to maintain both high productivity and pathogen-free status.

  • Knowing the optimal conditions and seasonality
    Knowing the optimal conditions and seasonality for the development of a given disease can be useful in the timing of any control measures.
    1. Sometimes this information is helpful to disease diagnosticians since they can make a special effort to look for target pathogens at certain times of the year. Scouting for disease only at times when conditions are favorable allow for better management of personnel resources.

    2. In addition, preventive pesticide applications should be recommended only when disease development is possible and not on a year-round basis, which is costly and potentially hazardous for the plants, the workers, and development of resistant populations.

  • Host nutrition
    Host nutrition has also been shown to affect severity of many diseases of ornamental plants. Both the rate of fertilizer and its source can affect disease development.

    Trials on hibiscus grown with different levels of slow-release fertilizer (Osmocote® 19-6-12) have shown that both plant quality and severity of Xanthomonas leaf spot were affected by fertilizer level. Plant quality was very high when they received between 5 g and 20 g of fertilizer per 5-inch pot. In contrast, disease severity increased as fertilizer rate increased up to the rate of 10 g per pot, then showed a rapid decline in severity above the rate of 12.5 g per pot. Use of 15 g to 20 g (1/2 oz to 3/4 oz) of fertilizer per pot resulted in excellent quality plants with very low levels of Xanthomonas leaf spot.

    Xanthomonas leaf spot, Chase Research Gardens

  • Resistant varieties
    Resistant varieties are very useful if they are available since they can be produced in the presence of the pathogen with a minimum loss to disease. The available information concerning disease resistance of hibiscus is limited at the present time; however, the development of resistant cultivars of many commercial crops is rapidly increasing with the advent of new technology.

  • Pesticide usage
    All of the above practices are recommended as standard procedure; however, pesticide usage remains the backbone of control for many severe diseases of ornamental greenhouse crops. Some excellent pesticides are labeled for control of many pests and diseases common to hibiscus and other ornamentals, with the exception of those caused by bacterial pathogens.

    Recent research on bacterial disease control using ten common cultivars of hibiscus has shown that plants treated with the growth regulator chlormequat chloride (Cycocel®) exhibited increased resistance to the pathogens (Ps. cichorii, Ps. syringae, and X. c. pv. malvacearum). The Cycocel was applied at the recommended rate, 3 times on weekly intervals prior to inoculation with one of the bacterial pathogens.

    Adapted from A.R. Chase, Professor of Plant Pathology, University of Florida

Diseases and disorders of hibiscus, Chase Research Gardens
Hawaii Pesticide Information Retrieval System Home Page, CTAHR
Pest management techniques for hibiscus disease, A.R. Chase, U. of Florida

Top of Page

New Books from Ball Publishing

Ball Publishing Batavia, IL, has two new books of interest to the Hawaii green industry. Tropical Foliage Plants: A Grower's Guide contains 300 pages devoted to 82 foliage species. It provides information on habitat, uses, cultivars and varieties, propagation, culture, nutrition, pests and disorders, and interior problems.

Ball Guide to Identification of Greenhouse Pests and Beneficials is a comprehensive guide to identifying insect pests and their natural enemies on crops grown in greenhouses. The book discusses how to establish an IPM program, the identification of major greenhouse pests, and looks at different types of pest damage to specific crops.

Top of Page

Cupric Hydroxide-treated Containers can Improve Bougainvillea Propagation and Growth after Transplanting

Jay Deputy, deputy@hawaii.edu
Education Specialist
Dept. of Horticulture, CTAHR

Root systems of bougainvillea typically circle the interior of the container outside the rootball when propagated by cuttings. These roots are brittle and easily broken off or injured during transplanting. However, researchers at the University of Florida have shown that the application of latex paint containing cupric hydroxide (13 oz/gal) to the interior of the container resulted in a root system that remained within the rooting substrate thereby reducing the possibility of injury to the root system, and hence transplant shock.

When rooted liners were transplanted to one gallon containers, those liners rooted in Cu(OH)2-treated containers resulted in larger plants 91 days after transplanting compared to those liners rooted in non-treated containers. Faster growing plants would allow for earlier upcanning, earlier sale of a certain sized plant, or result in a larger plant by a certain date.

Controlling rooting-out of B&B stock during storage, U. of Rhode Island.

Top of Page

Commercial Color

David Hensley, dhensley@hawaii.edu
Extension Landscape Specialist
Department of Horticulture, CTAHR

Seasonal displays of landscape color are important to corporate landscapes and to landscape managers. Beds of annuals, groundcovers, and perennials brighten and accent corporate headquarters, office buildings, hotels, shopping centers, apartment and condominium developments, parks, and metropolitan areas. Beds of flowering plants provide the competitive edge to convince people to patronize one restaurant, hotel, mall, or apartment complex over another. Flowers are used to make large residential complexes seem more like individual "homes."

Color has universal appeal. People prefer to live, work, and shop in pleasant environments, and colorful flowers certainly contribute to the "atmosphere." A summer survey of campus employees at Kansas State University asked about various aspects of the campus. The most frequent positive comment concerned the beds of annual flowers around the campus. This astounded the "powers that be"; they had never considered the impact of annual flowers beyond decoration and a budget expense.

Annuals or bedding plants are one of the least expensive ways to brighten a dull landscape and to attract attention. Some apartment, hotel, and office property managers consider the cost of bedding plant as an advertising expense rather than site maintenance.

Annuals are used in beds, borders, in containers, and many other landscape areas. Select colors carefully; the design should not be a collection of color nor species. Large massed beds of single-color annuals can be attractive and sophisticated. concentrate on the critical areas such as entry areas, signs, outdoor eating areas, and places where people congregate.

Be imaginative! Impatiens, begonias, marigolds, petunias, and annual vinca account for the vast majority of beddings plans sold. There are many other new and tried species and cultivars that are beautiful and tolerate a wide variety of environmental conditions.

Consider maintenance when designing annual beds. Although some annual flowers truly qualify as low-maintenance plants, most are not. Place beds away from street and parking lot curbs to reduce stress. Avoid small beds of less than 50 square feet. Locate flower beds a minimum of 6 feet from the base of shallow-rooted trees to reduce competition for nutrients and water. Be sure that there are water hookups near the bed. Even if there is an irrigation system, handwatering will be necessary during establishment and times of stress.

Plant selection
There are many species and cultivars of flowering annuals that vary in size, color, form, season of bloom, pest resistance, and environmental tolerance. Choose plants that tolerate the site environment. No amount of management can counteract the wrong plant for the wrong site.

Select and use only quality plants. Bedding plants should have healthy roots extending to all sides of the pot. The top should be deep green and well-proportioned to the container and character of the plant. Plants with excessive tops use more water than their small root systems can supply. Plants should be free of insects and diseases and hardened-off to prevent scorching in the full sun.

Plants grown in cell packs are the most important component of the retail bedding plant market. Commercial landscape managers generally want larger, more established plants. Plants grown in large cell pack and four- and five-inch pots are often used. Plant prices increase in direct proportion to the pot size. Large plants, however, provide immediate effect. The client sees the results of his/her expenditure immediately. In actuality, the individual cost of the plant is small when compared to labor and equipment for preparing, planting, and maintaining the bed.

Top of Page

About Research

Eileen Herring, eherring@hawaii.edu
Hamilton Library

Effect of pesticide-treated grass clippings used as a mulch on ornamental plants. B.E. Branham and D.W. Lickfeldt. 1997. HortScience 32(7):1216-1219.
When turf is treated with pesticides, the collected grass clippings become a potential source of injury to susceptible plants that come in contact with the clippings. In this study, grass clippings were collected at 2, 7, and 14 days after turf was treated with either chlorphyrifos, clopyralid, 2,4-D, flurprimidol, isoxaben, or triclopyr. The clippings were then used as mulch around tomato (Lycopersicon esculentum), bush bean (Phaseolus vulgaris), petunia (Petunia x hybrida), and impatiens (Impatiens wallerana).

Clippings from the clopyralid, 2,4-D, and triclopyr treatments killed tomatoes, beans, and petunias when mulched with clippings taken 2 days after treatment. These treatments also caused severe injury in the same species when clippings were taken 7 or 14 days after treatment. Mulch from the flurprimidol treatment injured tomato, bean, and impatiens plants at all treatment intervals, but was not lethal. Isoxaben also injured tomatoes and beans at all treatment intervals, but was not lethal.

In this study, clippings still contained enough herbicide residue after 2 mowings to cause significant plant injury. Clippings from turf treated with herbicides or plant growth regulators should not be used as a mulch for at least 2 weeks after application or until 3 mowings have been done. Rainfall or irrigation after application can reduce injury. The authors conclude that mulching ornamentals with grass clippings is an excellent way of disposing of yard waste, but returning grass clippings to the turf is the best option for their disposal.

Nitrogen source affects growth and quality of Bougainvillea. T.K. Broschat. 1998. HortTechnology 8(3):346-348.
Iron deficiency chlorosis is a common disorder in container-grown bougainvillea. The form of nitrogen in fertilizers has been shown to affect iron deficiency in some plants, and this paper reports the results of two experiments on container-grown Bougainvillea 'Brasiliensis.'

In the first experiment, plants fertilizer with sodium nitrated were stunted, extremely chlorotic, and produced few flowers in comparison to those receiving ammonium sulfate. In the second experiment, plants grown with only nitrate as a nitrogen source were chlorotic, stunted, and produced fewer flowers than those receiving nitrogen from urea or ammonium salts.

These studies showed that nitrogen source strongly affects the growth and quality of bougainvilleas. Although the physiological reasons are unclear, plants fertilized with controlled-release ureas were the largest, had the most flowers, and the least chlorosis and leaf spotting.

Interior plants may improve worker productivity and reduce stress in a windowless environment. V.I. Lohr, C.H. Pearson-Mims, and G.K. Goodwin. 1996. Journal of Environmental Horticulture 14(2):97-100.
Understanding the benefits of interior plants can help interior plantscapers sell their services. This study, using common interior plants in a computer lab, confirmed that interior plants can contribute to reduced stress. It also documented that the presence of plants can improve worker productivity on tasks requiring concentration and quick reactions. Participants' blood pressure and emotions were monitored while completing a simple, timed computer task in the presence or absence of plants.

When plants were added to the interior space, the participants were more productive (12% faster reaction time on the computer task) and less stressed (systolic blood pressure readings were lowered by one to four units). Immediately after completing the task, participants in the room with plants reported feeling more attentive than people in the room with no plants.

Factors affecting seed germination of the Mauna Kea silversword in Hawaii. L.R. Walker and E.A. Powell. 1995. Pacific Science 49(3):205-211.
The Mauna Kea silversword (Argyroxiphium sandwicense) is endemic to the slopes of Mauna Kea and, in nature, now has a population of less than 500 individuals. This study examined germination of seeds subjected to a variety of conditions. Germination was best in moist, shady conditions. The pericarp (fruit wall) inhibits germination, probably due to chemical inhibitors, and germination was highest when the entire pericarp was removed.

Neither cold nor heat pretreatments affected germination. Germination was highest for seeds less than 2 years old and for seeds collected directly from the flower stalks. Seed viability declined more rapidly when the seeds were in the soil than when they remained on the flower stalks, possibly because wetting may make the seeds more susceptible to extreme temperatures, drying, or fungal attack.

Vesicular-arbuscular mycorrhizal inoculation of Hawaiian plants: a conservation technique for endangered tropical species. R.E. Koske and J.N. Gemma. 1995. Pacific Science 49(2):181-191.
Conservation of many Hawaiian species has been handicapped by inability to cultivate them in the greenhouse. Studies suggest that 90% of Hawaiian flowering plants are dependent on their association with mycorrhizae. Routine greenhouse practices such as using soilless mixes and fungicides appear to effectively exclude inoculation with mycorrhizal fungi.

In this study, 40 species of plants, most of which were either endemic or indigenous to Hawaii, were evaluated for their response to inoculation with a commercial preparation (NutriLink) of vesciular-arbuscular mycorrhizal (VAM) fungus Glomus intraradicies. Seedlings, cuttings, and established plants in several kinds of growth media were inoculated.

The responses to inoculation were most striking in the seedlings. Survival of seedlings of ohia lehua (Metrosideros polymorpha) was significantly greater when inoculated. Cuttings routinely become mycorrhizal without inoculation, presumably to VAM fungi on the stem surfaces. Only eight of the 18 species of established plants tested showed a positive response to inoculation, but the high peat content of the mixes used for these plants may have reduced this result.

Although not all species tested responded to inoculation, in general, the plants grown in gravel or fine sand mixed with up to 50% by volume calcined clay (such as Terra-Green) showed the most consistent increased growth and survival. Significant increases in growth and survival also occurred in media consisting of gravel or fine sand and peat moss as long as the total peat moss content was not more than 20% by volume. Addition of mycorrhizal fungi to potting mixes appears to have value for some plants that are difficult to propagate and grow under greenhouse conditions.

Top of Page

Substituting Hawaiian Composts for Peat in Growing Media for Hibiscus

Julie Yogi1, David Hensley1, and James Hollyer2
Departments of 1Horticulture and 2Agricultural and Resource Economics, CTAHR

Sphagnum peat has been the primary organic constituent of nursery mixes in Hawaii. As the cost of peat continues to increase, the interest in using compose produced as nursery media also increases. There are presently green waste composting operations on Hawaii, Kauai, Maui, and Oahu, and a sewage sludge-green waste compost operation on Maui.

Composted organic materials have been successfully used as a nursery container medium on the mainland and in Europe and Australia. In Hawaii, acceptable growth and quality of several container-grown foliage species resulted when fresh or composted bagasse replaced one-third of the sphagnum peat used in potting medium. Plant growth and quality were reduced at higher percentage bagasse replacement.

The purpose of this study was to compare the growth of hibiscus produced in various levels of locally produced composts.

Materials and Methods
Rooted cuttings of Chinese hibiscus (Hibiscus rosa-sinensis) were planted in four-inch posts using a media in which local composts were substituted for peat. The control mix consisted of 2:2:1 peat:perlite:soil. Green waste composts from three Oahu producers and composted macadamia husk from the Big Island were substituted for 0% (control), 25%, 50%, or 100% of Canadian sphagnum peat. Each treatment was replicated 5 times. Nutrient content and pH of the composts and peat were analyzed by the CTAHR Soil Testing Laboratory. Each medium was supplemented with 8.5 pounds 18-6-12 Osmocote®, 1.7 pounds Micromax®, and 5 pounds dolomite per cubic yard.

Height measurements were taken 4 and 24 May, 23 June, 17 July, and 29 September 1995. The tops of the plants were harvested at the end of the study, and fresh weights measured. Total porosity was measured on 24 May 1995.

Results and Discussion
The results of the nutrient and pH tests are presented in Table 1.

Table 1.  Nutrient content (ppm) and pH of organic materials used to
grow hibiscus.

Compost          pH    Total N     P     Ca     Mg

green waste M    8.4     5.2      1.5   138.5   52

green waste A    6.7     4.1      4.0    30.5   13.5

green waste K    7.7     6.5     20      51.5   35.5

macadamia husk   6.1     1.6      0.0     9.0   11.0

peat (control)   4.1     0.3      2.5     4.5    3.0

Peat, as expected, was very acidic and low in nutrients. The pH and nutrient levels of the composts varied. The green waste composts contained higher levels of nitrogen and other nutrients. This reflects incomplete composting, that is, the materials were not truly finished composts. These materials would have continued to compost and reduce in volume. Yard trimmings and debris that have completed the composting process will have a nitrogen content of about 1% to 3%. The macadamia husk compost was a finished compost as indicated by the nitrogen content.

This does not mean that the green waste products cannot be used in a nursery media, however. They will provide a reasonable organic material for plant growth. Some of the nutrients contained in the green waste composts would become available to the plants over time. Most of the nitrogen, however, is held in a very slowly released organic form so the material does not generate enough heat in the containers to cause damage to the plants. It would require a much larger volume of material than small nursery containers in order to generate a heat of decomposition great enough to damage plants from the materials tested.

Water holding capacity and porosity of the media would be directly affected by the level of composting of the organic material. As organic materials compost, their particle size is reduced. Finished compost would have smaller particle size and therefore better water holding capacity.

The potting mix must have adequate large pore space to be well aerated for the roots. Excessively large pores decrease the amount of water the media can store. The particles of organic material may become small with time due to decomposition and can sift down in the pot clogging the pores and reducing aeration over time. The material needs to be relatively stable to avoid this problem.

For outdoor production, container media should have large or drainable pore space of 20 to 30 percent of the volume. This range provides good aeration and water capacity and allows excess water to drain away.

Green waste compost "A" was the coarsest compost tested, and this is reflected by the greater porosity in each level of substitution for peat (Table 2).

Table 2.  Porosity of media with various percent 
compost substituted for peat.

                 Percent substitution for peat
                    0      25     50    100

                      Media porosity (%)
  green waste M    21.1   24.0   35.0   30.0

  green waste A    21.1   31.3   35.4   39.1

  green waste K    21.5   22.8   29.9   36.3

  macadamia husk   21.5   30.2   22.9   25.6

There were no statistical differences among
any substitution levels for the materials.

This materials would require additional irrigations if used as a high percentage of a container mix. Green waste compost "K" would also require additional irrigation to maintain adequate moisture for the plans if the material were used as the primary organic material in a mix. The coarseness of these two materials reflects incomplete composting. Green waste compost "M" and macadamia husk compost, both more completely composted, were within the desirable porosity range.

Height. Hibiscus grew successfully in all media tested. There was no statistical differences in plant height during the course of this study among any of the levels of composts substituted for peat.

Fresh weight. There were noticeable differences in the fresh weights of the harvested plants at the end of the study, however (Table 3).

Table 3.  Fresh weights (g) of hibiscus grown in
media with various percent composts.
                    Percent substitution for peat

                     Fresh weight at harvest (g)
  green waste K    61.0   57.3   56.5   48.0

  green waste A    61.0   66.5   58.8   62.3

  green waste M    61.0   53.0   51.5   45.3

  macadamia husk   61.8   67.5   63.7   74.5

There were no statistical differences among any 
substitution levels for the materials.

There were no statistical differences among any of the substitution levels for any of the materials. Plant weight n media containing green waste compost "M" were slightly less than the peat control at all levels. Green waste "K" provided growth equivalent to the peat control except when used alone. The total size of the plants produced in the third green waste and macadamia composts were equivalent or slightly greater than peat alone.

The goal of this small study was to determine if locally produced composts could be substituted for peat in production of red hibiscus, a common landscape plant.

  1. The results indicate that growth of red hibiscus in media containing 25%, 50%, or 100% of the composts substituted for peat was comparable to peat alone.

  2. Two of the materials tested were coarse and would likely require more irrigation than finer textured mixes if these materials were used alone or as a majority portion of the organic constituent.

Research elsewhere has also indicated that composts can successfully replace at least some of the peat in nursery mixes.

We do not mean to suggest from these results that growth or quality would be the same with every plant in a compost or compost-peat media. Do some experimentation in your operation to determine the suitability of a locally available organic material. Evaluate what level of substitution might work best for particular plants, and compare cost and quality. Supplemental fertilization may also require some fine tuning.

Research conducted in Hawaii and elsewhere indicates that there can be differences in the quality of compost. Variation can occur with batch, season, and with changes in the raw inputs. Look particularly for a finished or mature product. Look at stability in particle size, pH, and soluble salts. Soluble salts of some composts can be quite high, but can be reduced by leaching. Variation in batches of composts diminishes dramatically as producers gain experience and technology. Most composters in Hawaii have found stable sources of input material and are now producing a consistent product.

None of the composts tested would be suitable for producing certified nursery material for export. All of the materials were produced or stored on the ground, and this is a no-no for export media. They appear, however, to have good potential for production of nursery stock for local consumption.

Free CTAHR publications on composts and substitutions for peat in media

Top of Page

Development of a New Yellow Impatiens wallerana

Jay Deputy, deputy@hawaii.edu
Education Specialist
Dept. of Horticulture, CTAHR

Researchers at the University of Connecticut have developed the first true yellow Impatiens wallerana. The research was funded by Bodger Seeds, South El Monte, CA. Bodger Seeds is now marketing several forms of the plant as the Seashell impatiens series.

The plant was developed by crossing the color gene from one of the many yellow-flowering impatiens species, such as I. capensis and I. pallida, with the compact habit of I. wallerana. When species are cross-pollinated, the results usually vary widely. Most impatiens interspecific crosses produce see that is not viable. The university researchers, however, employed techniques that ensure the seed embryos would germinate.

Seashell impatiens has a habit similar to common I. wallerana, but is somewhat more vigorous. It grows well in partial sun to full shade, and pinching increases branching, controls plant height, and stimulates flower production. The cupped, shell-like flowers are available in six colors: yellow, apricot (light orange), papaya (rose with an orange blush), passion (light salmon-rose), peach (soft salmon-pink), and tangerine (neon orange). According to Bodger Seeds, Seashell impatiens are excellent container plants that combine well in landscape compositions.

What patience grew--This spring, look for yellow impatiens, once thought impossible to breed, Ottawa Citizen.

Top of Page

Getting to the Root of the Matter

Dr. Mike Schnell
Extension Specialist
Oklahoma State University

Roots are the underground portions of plants that absorb and conduct water and minerals, and provide support for the plant. Researchers have been able to gain an understanding of some of the basic functions of roots, but our understanding of the plant root zone is still very limited. Roots comprise less than half of a plant's dry weight, yet the surface area of the root system is much greater than that of the shoots.

  • Morphology and function of roots

    There are two basic types of roots--nonwoody and woody.

    Nonwoody roots
    Nonwoody roots are found mostly in the upper 6 to 12 inches of soil. Nonwoody roots provide minimal anchorage, but store large amounts of carbohydrates in specialized units called amyloplasts. The primary function of nonwoody roots is absorption of water and mineral elements. They are best referred to as absorbing roots, rather than "feeder roots."

    Root hairs
    Root hairs are extension of surface cells that vastly increase the absorbing surface of the root. Root hairs have a thin cuticle layer that offers little resistance to water and nutrient uptake into the plant. Some roots are also coated with a slimy material known as mucigel. Mucigel lubricates the roots and promotes a more intimate contact with soil particles.

    Some plants, such as pine, do not have root hairs, but possess mycorrhizae. Mycorrhizae are fungi that live in partnership with roots. The fungi absorb organic compounds (food) from the plant and, in turn, increase soil nutrient and water absorption capability of plant's roots. Both organisms benefit, and neither is harmed. A nice arrangement.

    Woody roots
    Woody roots are large lateral roots that form at the base of the trunk of trees. Woody roots provide anchorage and support for the tree. They form the framework of the root system. Woody roots also transport water, minerals, and organic compounds and store carbohydrates.

    Striker roots
    Some trees have striker or sinker roots that extend downward until obstacles or insufficient oxygen prevents further growth. Striker roots are much like tap roots in that they store water and carbohydrates for energy.

    Adventitious roots
    Adventitious roots, another type of roots, often form spontaneously on large basal roots and develop as a result of injury. Mechanisms that trigger adventitious root formation are not well understood. Flood tolerant species develop adventitious roots when flood stressed, apparently as an oxygen gathering adaptation. Adventitious roots found on English ivy, poison ivy, and pothos help these species climb on vertical surfaces.

  • Challenging myths with research

    Horizontal root spread. The horizontal root spread achieved by trees in relation to a plant's canopy or "dripline" has long been misunderstood. Roots of trees were once believed (and still is by some) to grow outward only to branch tips or edge of the canopy (dripline). The majority of fibrous roots were thought to be concentrated at the dripline. Research, however, has shown ample evidence to the contrary.

    Researchers have measured the spread of many tree species and found that roots grow well beyond the dripline of the canopy. Some of this work is many years old. Maximum root spread ranged from 1.68 times the dripline distance (radius) for green ash to 3.8 times for southern magnolia. The extent of a tree's root system will ultimately depend on the tree species, the soil, and the environment.

    Underestimating the extent of a tree's root system has led to injuries to woody plants from misapplied herbicides (especially soil sterilants), fertilizers, soil-injected insecticides, and other treatments. Applicators often assume that chemicals can be safely applied when outside the dripline. The majority of roots, as determined by weight, are probably found within the "dripline." However, absorbing roots critical for absorbing water and nutrients are predominantly found beyond the periphery of a tree's canopy.

    Root depth. The depth to which the tree's roots grow has often been grossly exaggerated. Deep root systems are the exception rather than the norm for trees. Some pines found in Texas may grow roots 10 feet or more downwards. Mesquite (Keawe) has been known to send roots penetrating to depths of 80 feet in the soil, but this is uncommon for most species.

    Root distribution of most temperate and tropical shade trees is often shallow. Little, if any, root growth occurs below 48 inches in depth. Knowing that most absorbing roots are indeed in the top few inches of soil reveals why they are so easily uplifted during slight soil disturbances.

  • Soil oxygen deficiencies

    Flooding. Roots develop in the top few inches of compacted, heavy clay, wet, or urban soils, because the soils are waterlogged. Waterlogged soils are oxygen deficient, preventing respiration by the roots. Water holds less than 1/10,000 as much oxygen as air. Roots of plants growing in poorly aerated soils are thicker, shorter, distorted, and with fewer root hairs. As the oxygen supply decreases, the ability of roots to grow and penetrate the soil decreases. Prolonged soil flooding may lead to anaerobic conditions and the accumulation of substances toxic to roots.

    Barriers. Construction activities such as paving can reduce oxygen levels from 18% to as low as 3% in some instances. Solid plastic barriers, sometimes used under mulches, reduce gas exchange by the soil. One improvement is the advent of woven or spun bound weed barriers that "breathe."

    Construction and compaction. Reduced soil aeration is the most common construction damage to trees. Compaction from machinery or traffic and grade changes can result in severe oxygen starvation to tree roots.

    A newly planted tree can often establish roots after a grade change, but one cannot expect an established tree to tolerate drastic changes in soil level. Some trees adapt by developing shallower roots where oxygen is more available from adventitious growth. Many species and individuals, however, cannot adapt quickly enough before they succumb to root suffocation. You can't teach an old tree new tricks!

    Secondary effects of oxygen starvation. Sublethal lack of soil oxygen stress leads to several secondary problems. The defense system of any tree is compromised when the tree is weakened. High soil moisture can lead to root decay caused by Phytophora and other disease fungi. Disease and insect related problems resulting from oxygen induced stresses decrease leaf production. Reduced foliage, in turn, lowers carbohydrate production needed for proper root growth.

    Root zone stresses create a cycle of decline for shoot and root growth, eventually killing the plant. Water and nutrient absorption is reduced because of reduced permeability of roots to water. The tops of trees in extremely wet situations will wilt even though the roots are covered with water. Several critical plant hormones are produced in the plant's roots. Their production is altered in roots growing under low oxygen conditions. Lastly, mycorrhizal colonization and function is hampered by excessive moisture and low soil oxygen.

    Root adaptations. Trees try to adapt to planting in oxygen deprived soils. Roots respond to low oxygen supply by growing closer to the soil surface. Research has shown that shallow planting of trees in heavy or compacted soils enables more rapid establishment due to improved root growth because of the better oxygen relations. In areas where soils are heavy clay, trees benefit by planting them a few inches above grade.

    Temperature. Temperature extremes also significantly affect root growth. Soil temperatures below freezing cause root growth to nearly cease (not a problem in Hawaii). However, high temperatures, above 95° may be lethal. Effects from temperature extremes are most profound when plants are grown in containers. Excessive root zone temperatures from nearby asphalt and concrete can cause tree and shrub decline in urban plantings. Optimum temperatures for root growth of most trees is 61° to 81° F.

    Competition for resources. Root systems are also stressed when planted into highly competitive areas. Sod competition exacerbates nutrient and water deficiencies. Indirect damage to tree roots can results from pesticides intended for lawn care. Some grasses produce allelopathic chemicals that prevent or reduce the growth of some trees.

    Mulch enhances root growth of trees. removing grass from around recently planted trees is best for fine root development of trees. Removing grass immediately around the tree's trunk reduces water and nutrient competition and avoids lawn mower and weed whacker injury, and any allelopathic effects from the grass.

    Pruning. The merits of pruning newly planted trees is still debated. Various researchers have looked at root and/or shoot pruning on bare root plants at planting. Species react differently to pruning at planting. While pruning reduces potential water loss by reducing leaf surface area, it also reduces carbohydrate and hormone production by the shoot. As a compromise, prune trees at planting to remove damaged branches and to shape the plants. Do not indiscriminately remove limbs or parts of limbs.

    Staking. Staking of newly planted trees is also somewhat controversial. Research has absolutely shown that prolonged or too rigid of stacking does not allow for swaying of the tree resulting in inferior root growth as well as other undesirable effects to the tree. Stake trees so that there is still some movement allowed and remove stakes and guys as soon as possible.

    Countless other factors play direct or indirect roles in development or prevention of healthy root growth. Roots, although vital, are the least understood and least researched portion of the tree.

    Adapted from Root Systems of Trees--Facts and Falacies by Michael A. Schnelle (mas@okway.okstate.edu), James R. Feucht, and James E. Klett. 1989. Journal of Arboriculture 15(9):201-205.

    Top of Page

    How Loud is Loud?

    David Hensley, dhensley@hawaii.edu
    Extension Landscape Specialist
    Dept. of Horticulture, CTAHR

    What is a safe noise level for the operator of gas-powered landscape equipment such as mowers, trimmers, or blowers?

    Safety levels are often arbitrary so it is difficulty to say what level of noise is "safe." The Occupational Safety and Health Administration ( OSHA) calculates thresholds above which employers must provide ear protection for exposed employees. OSHA uses a rather involved computation, taking into account noise levels as well as duration of exposure. Both are important factors for assessing risk to hearing. However, a time-weighted average of 85 decibels over an 8-hour day is a level OSHA generally considers harmful.

    For a loose comparison, heavy city traffic has been measured at around 85 decibels. A vacuum cleaner at 5 feet can produce 80 decibels, and a blender can emit 90 decibels. Because duration of exposure is such a critical factor, you cannot judge risk by decibels alone. However, many times of landscape equipment clearly exceed 85 decibels.

    Few federal or state regulations address noise standards for outdoor power equipment. In fact, few standardized tests to define power-equipment noise levels even exist, though the American National Standards Institute (ANSI) is doing some work in this area. Several cities and towns enacting noise ordinances aimed at lawn and garden equipment (especially power blowers) have used arbitrary noise standards. this legislation is meant to address noise as a nuisance, not a safety issue. Blowers have been banned in many localities. These requirements are usually far more stringent than safety concerns dictate.

    It is the employer's responsibility to supply ear protection to employees if high noise levels call for it. Such requirements are sometimes ignore in the turf and landscape industry. However, prudent landscape workers wear ear protection as standard practice. After all, ear plugs or covers is not really a major inconvenience and can protect hearing in later life.

    Top of Page

    Production Methods Can Affect Transplanting of Trees

    David Hensley, dhensley@hawaii.edu
    Extension Landscape Specialist
    Department of Horticulture, CTAHR

    Landscape professionals usually have a choice between container and field-grown trees for landscape installation. Does one type establish faster than the other? Researchers at the University of Florida conducted two studies to determine if and how production methods altered root distribution and establishment rates of transplanted trees.

    The researchers grew laurel oaks and 'East Palatka' hollies in the field in plastic containers, and in fabric "grow bags" in field soil. After 2 years of growth, they analyzed the trees from each group for small- and large-diameter roots within the root balls of field-grown trees (after being balled and burlapped for transplanting) and the "grow bag"-grown trees (also faster preparation for transplanting which included digging and removing roots outside the fabric container). Unlike some previous studies, the investigators looked at root mass, not length. Further the researchers looked at establishment rates for trees from each group by measuring growth rates and root development subsequent to transplanting.

    Field-grown trees lose much of their root systems during digging. Not surprisingly, the root balls of container-grown trees contained several times the fine-root mass of the root balls of field-grown and "grow bag"-grown trees. This accounts for the ability of container-grown trees to rapidly remove water from their root balls. However, total root mass was lower in container-grown plants, which had fewer large roots than field-grown or "grow bag"-grown plants.

    Relating these findings to establishing rates, the researchers noted that little difference existed among the trees after transplanting as long as regular irrigation occurred. However, when irrigation was reduced 14 weeks after transplanting (a test of how rapidly establishment was occurring), the field-grown trees experienced less water stress than the container-grown transplants. The field-grown and "grow bag"-grown transplants had completely replaced roots lost from digging within 6 months of transplanting and matched or exceeded the growth rates of container plants 1 year after transplanting.

    In light of these results, the researchers suggested that the value of large roots in relation to transplant establishment needs further investigation--they may be more important than expected. Fine roots, although obviously important or water uptake, did not provide any advantage beyond the short term in this study. This is not so surprising in view of the fact that fine roots generally are short-lived, being shed by plants after a few weeks. Based on this study, the researchers suggest that production methods that encourage retention of more medium and large roots should be explored.

    Top of Page

    Mature Tree Care

    International Society of Arboriculture

    When one considers that the value of a healthy tree increases as it ages, and that some tree species can live as long as 200 to 300 years, then providing regular care for trees is like putting money in the bank. Curing a problem once it develops is much more difficult, time-consuming, and costly than preventing one. Therefore, it is worthwhile to give trees regular maintenance to ensure that they are able to offer enjoyment and value for generations. An effective tree maintenance program should include four major practices:

    • inspections
    • mulching
    • fertilizing
    • pruning

    Tree inspection
    Tree inspection calls attention to any change in the tree's health before the problem becomes too serious. By providing regular inspections of mature trees (at least once a year), you can prevent or reduce the severity of disease, insect, and environmental problems. During the inspection, be sure to examine four characteristics of tree vigor:

    • new leaves or buds
    • leaf size
    • twig growth
    • crown dieback

    A reduction in the extension of shoots or in the size of leaves is a fairly reliable cue that the tree's health has recently changed. to evaluate this, compare the growth of shoots over the past 3 years. Determine if there is a reduction in the tree's typical growth pattern. Further signs of poor tree health are stem decay and crown dieback. These symptoms often indicate problems that began several years before. Loose bark or deformed growth such as stem conks are common signs of stem decay.

    Mulching reduces stress by providing trees with a stable root environment that is cooler and contains more moisture than the surround soil. Mulch can also prevent mechanical damage by keeping machines such as lawnmowers and weed whackers away from the tree's base. Further, mulch reduces competition from surrounding trees and turf.

    To be most effective in all of these functions, mulch should be placed 2 to 4 inches deep and extend as far as possible from the base of the tree (at least 2 feet for young trees). Keep mulch a few inches away from the trunk to prevent rodent and other bark-eating pests from debarking.

    An adequate mulch layer is 2 to 4 inches of loosely packed organic materials such as shredded leaves, pine straw, peat moss, or composted wood chips. Plastic sheets should not be used because they interfere with the exchange of gases between soil and air, and inhibit root growth. The thickness of the mulch layer is important; mulches 5 or 6 inches thick may inhibit gas exchange.

    Fertilization is another important aspect of tree health care. Fertilizer is best applied right before a flush of growth, usually in fall and early spring, although it is not harmful to apply fertilizer at any time during the year. In addition to providing major nutrients, fertilizers can be used to increase the amount of 3 minor nutrients in the soil.

    Nitrogen is the most critical of the major nutrients. It is the element most responsible for maintaining the green color in leaves and for normal twig growth. Because nitrogen is rapidly depleted from the soil, it must be replenished regularly to ensure plant health.

    Phosphorus assists in the maturation of tissues and is particularly important in flower, fruit, and seed production. Fortunately, phosphorus in the soil is not depleted as rapidly as nitrogen, yet is sparsity may limit the number of plants that can thrive in a particular area.

    Potassium assists in the manufacture of sugar and starches, helps tissues mature properly, and may heighted the color of flowers.

    Pruning should be done regularly to control tree shape and keep branches from harming people or surrounding structures. Pruning should always be performed sparingly; overpruning is extremely harmful because without enough leaves, a tree cannot gather enough sunlight to survive. In some cases, however, pruning is absolutely necessary because damaged limbs pose a threat to healthy parts of the tree or to surrounding structures.

    Pruning also directs the growth of a tree. Branches typically grow in the direction that the buds are pointing, and the outermost bud on a branch has the most influence on the direction of future growth. Therefore, you can control the orientation of a branch by carefully selecting the location of the pruning cut. Cut so that the outermost bud on the branch points in the direction you want the branch to grow. Once you begin a cut, always finish it.

    Prune limbs and branches so that you preserve the branch's collar. This often appears as a collar of rough bark on the trunk formed in the "Y" of a growing branch. The final pruning cut should also be angled so that it begins in the crouch and extends down and outward at an opposite angle to the branch collar. This will not result in a cut flush with the trunk; rather, the base of the cut will extend out from the trunk. A healthy tree will seal on its own so wound dressing, which may actually interfere with the process, is not necessary. To aid in the recovery of cuts, water and fertilize trees well.

    Top of Page

    Frit Fly Alert

    David Hensley, dhensley@hawaii.edu
    Extension Landscape Specialist
    Department of Horticulture, CTAHR

    The frit fly (Oscinella frit), not fruit fly, is usually thought of as more of a turfgrass nuisance than a damaging insect on golf courses. The flies often hover over golf tees or areas of the fairway. Frit flies are also attracted to white objects such as golf balls, towels, and golf carts. But, the tiny frit fly is responsible for more damage, generally to golf greens and collar, than recognized. Damage occurs when larvae feed on the terminal shoots of grasses.

    In the past month, we have received 2 calls from golf course superintendents on Oahu with frit fly infestations causing significant damage to bermudagrass fairways.

    The adult frit fly is a minute black fly with yellow on its legs, about 1/6 inch (4 mm) long. They may be found in collected clippings of the greens. Frit flies congregate over greens in the midmorning (I guess they like to sleep in).

    The adult flies do not damage grass, but are a nuisance, laying eggs on the leaves and leaf sheaths. The yellow-white, legless maggots hatch and burrow into grass stems to feed. Females do not mate until the second day. Eggs are usually laid on leaves, in leaf sheaths, and in the grown stubble. Females live about 3 weeks and produce around 45 eggs. As with most insects, large numbers of adults may indicate a damaging infestation of larvae in a few days or a week or two.

    Damage may appear as scattered yellow or dead leaves throughout the turf. Close examination reveals a central dead leaf, or possibly the entire shoot will be dead. Feeding in the upper primordial leaves causes generally yellow and death of the central leaf, while surround shoots remain green. Frit fly maggots may be found feeding a the base of the dead leaf on the dead shoot. Tunneling of the stems near ground level causes the upper portion of the plants to brown and die. The yellow-white, legless worms move about when disturbed.

    On golf courses, damage is often first apparent on collars and approaches the center of the green. Higher elevations of greens are usually the first to show symptoms. Greens with soil high inorganic matter appear more susceptible. Infestations and damage appear worse following fertilization. Increasing the amount of slow release nitrogen in the fertilizer or reducing the rate per application may reduce damage somewhat.

    Control of frit flies is sometime justified to keep the adult flies from bothering people on the golf course or elsewhere and if damage is significant. In the case of the 2 Oahu courses, damage was severe. Chemical controls applied to golf greens, collars, and localized areas in fairways will reduce the population of this fly; however, eradication is difficult to impossible.

    Chemical controls include chlorpyrifos (Dursban®), according to Biology and Control of Insects and Related Pests in Turfgrass (1997). One superintendent had used chlorpyrifos and was not having much luck. The February 1998 issue of Grounds Maintenance article, "Turfgrass Chemical Updates: Insecticides," indicates diazinon (which is not labeled for golf courses) and permethrin for frit fly control, but not chlorpyrifos. Be sure to apply enough material. Recommendations I have read call for 3 gallons of spray per 1,000 square feet. This may be a higher rate than you normally use.

    According to Jim Petta with Zeneca, Scimitar®, as with most pyrethroids, is extremely active against most Dipterous (fly) pests, although he has not personally dealt with the frit fly. Petta recommended Scimitar GC®, the golf course product, at 10-20 oz/acre and see what results you get. The only negative is Scimitar and all of the other pyrethroids are Restricted Use Products for golf courses. The Scimitar CS® is not restricted, but it has all turf areas except golf courses on the label.

    The attraction of the insect to white objects may open the door to make "sticky traps" to grab the insects. Every female captured is 40 or so fewer maggots you have to deal with later. Yellow stick cards have been successfully used to reduce numbers of adult insects in greenhouses.

    Keep an eye out for the insect and damage. If you see significant numbers of adults or damage starting to show up, seriously consider applying controls.

    Top of Page

    Happenings at UH

    Several things are happening at UH that will affect the landscape industry. First, the College of Tropical Agriculture and Human Resources (CTAHR) is undergoing reorganization. The College will become the College of Tropical Agriculture and Resource Management (CTARM). The college will go from 11 current departments to 6 new departments--Plant and Environmental Protection Sciences (PEPS); Human Ecology and Applied Economics (HEAE); Human Nutrition, Food and Animal Sciences (HNFAS); Molecular Biosciences and Biosystems Engineering (MBBE); Natural Resources and Environmental Management (NREM); and Tropical Plant and Soil Science (TPPS).

    The University of Hawaii and CTAHR have suffered serious staff and budget cut-backs in the past few years. These losses for CTAHR have included a 50% reduction in operation costs and over 30% reduction in personnel over the past 5 years. We have lost 3 extension specialists and 1 country agent working in ornamentals and turf. Continued cut-backs of at least 4% annually are expected for the next 3 years. The reorganization will likely results in leaner and more client-focused programs. Many other land-grant universities in the continental USA have undergone or are currently experiencing similar "re-organization" programs.

    The reorganization will not officially take placed until all the paperwork is finished (there are mountains of it) and it is approved by the UH Board of Reagents. The entire process will probably be completed in about a year. Until then, everything is business as usual.

    The Department of Horticulture, formerly chaired by Dr. H.C. Bittenbender, will become the core of the new Department of Tropical Plant and Soil Science. The new department will incorporate everyone currently in Horticulture, except for Dr. Roy Nishimoto and Dr. Joe DeFrank. They will be moving to the new Department of Plant and Environmental Protection Sciences. However, many of our county agents and several members of the departments of Agricultural and Resource Economics, Agronomy and Soil Science, and Plant Molecular Physiology will be joining the new Tropical Plant and Soil Science.

    Since July 1, 1998, Dr. David Hensley has chaired the Horticulture Department as well as the soon-to-be Department of Tropical Plant and Soil Science. Dr. Hensley will continue his duties as Landscape Extension Specialist, but on a half-time basis.

    Mr. James (Jay) Deputy, who recently transferred from Plant Molecular Physiology, has joined the Horticulture Department as an Education Specialist working in the landscape and turfgrass area with Dr. Hensley. Jay will develop and produce educational programs and materials. We will also hopefully be addiing a part-time educational assistant for the landscape extension program.

    Top of Page

    On the Web

    Some web pages you might find interesting:

    On lawns and gardens from John Deere

    On turf and landscape, The Lawn Institute

    On recent research in agriculture, US National Arboretum Floral & Nursery Plants Research Unit

    Free publications from UH-CTAHR

    Knowledge Master, UH-CTAHR integrated pest management program

    Top of Page

    This newsletter is produced in the Department of Horticulture, a unit of the College of Tropical Agriculture and Human Resources (CTAHR), University of Hawaii at Manoa, as a participant in the Cooperative Extension Service of the U.S. Department of Agriculture. CTAHR is Hawaii's Land Grant institution established in 1907 from which the University of Hawaii developed. For information on CES horticulture programs or to receive future issues of this newsletter, please contact:

    David Hensley or Kenneth Leonhardt
    Department of Horticulture, University of Hawaii
    3190 Maile Way, St. John 102
    Honolulu, HI 96822-2279

    Mention of a trademark, company, or proprietary name does not constitute an endorsement, guarantee, or warranty by the University of Hawaii Cooperative Extension Service or its employees and does not imply recommendation to the exclusion of other suitable products or companies.

    Caution: Pesticide use is governed by state and federal regulations. Read the pesticide label to ensure that the intended use is included on it, and follow label directions.

    Top of Page

    Thank You. We hope you enjoyed this issue of Landscape, Floriculture, and Ornamentals News.

    David Hensley, dhensley@hawaii.edu
    Kenneth Leonhardt, leonhard@hawaii.edu
    CTAHR Extension Horticulture Specialists

    ...Return to lfon Main...

    Home | Academics | Faculty and Staff | Links | News | Research and Extension | Students | Contact Us