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LANDSCAPE, FLORICULTURE, AND ORNAMENTALS NEWS
Hawaii Cooperative Extension Service
No. 3, April 1998
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Hawaii Cooperative Extension Service
No. 4, November 1998
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.
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.
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.
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.
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.
- 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.
- 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.
- Media must be mixed and held in areas which are not contaminated
with native soil.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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 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.
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.
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
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.
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.
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.
Design
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.
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.
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.
Porosity
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 (%) Compost 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.
Growth
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
0
Fresh weight at harvest (g)
Compost
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.
Conclusions
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.
- 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.
- 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.
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.
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.
This spring, look for
yellow impatiens, once thought impossible to breed, Ottawa Citizen.
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.
Mycorrhizae
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.
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 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 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.
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.
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
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
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
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.
Frit Fly Alert
David Hensley, dhensley@hawaii.edu
Extension Landscape Specialist
Department of Horticulture, CTAHR
Problem
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.
Biology
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
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
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.
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.
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.
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
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81/10B Ho Van Hue Street, Phu Nhuan District, Ward 9, Ho Chi Minh City, Vietnam
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