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Green-seeds.com:
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LANDSCAPE, FLORICULTURE, AND ORNAMENTALS NEWS
Hawaii Cooperative Extension Service
No. 7, January, 2000
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TABLE OF CONTENTS
Kenneth W. Leonhardt, leonhard@hawaii.edu
CTAHR Extension Horticulture Specialist
James C. Deputy, deputy@hawaii.edu
CTAHR Education Specialist
Last modified: March 2000
Kent Kobayashi, kentko@hawaii.edu
Dept. of Horticulture, CTAHR, Univ. of Hawaii
CTAHR AND HAN TO SPONSOR WORKSHOP 
Jay Deputy, deputy@hawaii.edu
Education Specialist, CTAHR
 The University of Hawaii,
College of Tropical Agriculture and Human Resources, in conjunction with
Hawaii Association of Nurserymen will present a workshop titled "A Landscape
and Ornamentals Short Course". The program is to be held on Tuesday Feb.15
and Wednesday Feb.16, 2000 at the Honolulu Country Club. All members of
Hawaii's Green Industry are encouraged to attend. The audience should find
the speakers well informed and the topics very current. The program is intended
to bring Hawaii's landscape and nursery industry professionals together
with national and local members of USDA, University of Hawaii researchers,
and other noted professionals of the Green Industry from Hawaii and the
Mainland.
UH researchers
Dr. Arnold Hara (arnold@hawaii.edu)
and Dr. Janice Uchida (juchida@hawaii.edu)
will present information on current advances in local plant protection programs.
Dr. Hara, Entomologist and Extension Specialist in the Dept of Entomology,
will speak on biorational or "reduced risk" pesticides, including Merit,
Cinnamite, Floramite, Conserve and Millenium. These pesticides are synthetic
or natural products that effectively control insect pests, but with low
toxicity to nontarget organisms, and are nonpolluting to the environment.
He will discuss resistance management strategies for these biorational insecticides
and miticides, and share results of efficacy and phytotoxicity tests conducted
in Hawaii on alien pests. Dr. Uchida, Associate Plant Pathologist in the
Department of Plant Pathology will cover topics dealing with recent advances
in tropical plant diseases.
The USDA will
be well represented at the meetings, with Dr. Jerry Quisenberry, Director
of the new U.S. Pacific Basin Agricultural Research Center which is
presently under construction in Hilo, and Dr. Peter Bretting, from USDA/ARS
in Washington, D.C. Dr. Bretting is the national leader of a new program
in floral and nursery crops. Prior to 1997, ARS did not conduct research
in this area. Bretting's purpose will be to help get Hawaii's nursery and
floral industry involved in this national program.
Quisenberry will
discuss the role of the new USDA facility in Hilo. The mission for PBARC
is to increase the economy and wellbeing of Hawaii and Pacific Basin societies
by strengthening their agricultural sectors, thereby providing opportunities
in agriculture for the next generation. The Center's mission is also to
strengthen small farming culture by focusing upon the development of crops
and farming systems, provide necessary profitability and efficiency to those
farms and farmers, and at the same time develop farming practices consistent
with the preservation of fragile island ecosystems.
Quisenberry will
be accompanied by Dr. Robbie Hollingsworth, Research Biologist at PBARC.
Dr. Hollingsworth will speak on the feasibility of biological control for
insect and mite pests on ornamental crops. Also on the program is Dr. Neil
Reimer of the Hawaii DOA who will speak on the growing Fire Ant problem
in Hawaii and other quarantine issues.
Several mainland
agribusiness professionals will make presentations over the two-day session.
Of particular interest will be Dr. Jim Knauss who will speak during lunch
on the first day and give two separate presentations on the second day.
Knauss has been in the horticulture/floriculture industry since 1963. He
has been a professor of plant pathology at a mainland university and served
several commercial companies in a variety of ways. He is currently Director
of plant protection for The Scotts Company. The lunch topic will be a discussion
of Contrast and Ovation, two new products from Scotts.
The second day
presentations are "Disease and Pest Diagnosis" and "Plant Nutritional Diagnosis".
The program will also feature Dr. Bill McElhannon who obtained his Masters
and Ph.D. from the University of Georgia, and has over 20 years of experience
in the horticulture industry. He is currently Chief Horticultural Consultant
for Micro-Marco Analytical Laboratory and Director of Technical Services
and Research for Agrivert Inc., world wide suppliers of Nutricote controlled
release fertilizer. McElhannon's topic will be "Plant nutrition in containers
and in the landscape". He will discuss how to design a complete fertilizer
program for container production or the general landscape.
Rounding out the
mainland guest speakers will be Karl Drescher of Chem Search/OptiGrow Inc.
Drescher's topic will be "Fertigation - A tool for nursery/landscape professionals".
Two local agribusiness
professionals are also scheduled to speak. Ray Cain, Vice Chair of Belt
Collins Holding Co., an international planning, engineering, environmental
consulting and landscape architectural firm, will speak on "Golf Course
Landscaping with Maintenance in Mind". Mr. Cain's specialty is hotel, resort,
and golf course development projects. His company has worked on most of
the major resort projects throughout Hawaii and in over 55 different countries
in Asia and the Pacific basin.
The second local
Green Industry speaker is Garrett Webb, a landscape contractor in Kona,
and president of Hawaii Island Landscape Association (HILA). Webb is also
presently serving as Project Director for the recently initiated Certified
Landscape Technician (CLT) Program on the Big Island, funded through HILA
by the State of Hawaii Dept. of Labor and Industrial Relations. The CLT
Program is administered by the Associated Landscape Contractors of America
and also offers certification in Irrigation and Construction as well as
in Maintenance. Mr. Webb will be speaking about this new pilot program for
the Big Island and of the possible development of similar programs on Oahu
and Maui in future years and of the CLT in Irrigation on the Big Island
next year. Other speakers from local industry may also make presentations.
The cost of the
two day program, which includes lunch both days and refreshments at all
breaks, is $75 for current HAN members and $100 for all others. Special
room rates are available for off island participants at the Outrigger Hobron
Hotel.
Any questions
or requests for hotel reservation or program registration forms can be directed
to Madeleine Shaw at (808) Limited space is available and early registration
is advised. The deadline for regular registration is Jan. 31, 2000.
CTAHR RELEASES SEVEN NEW HYBRID PINCUSHION PROTEA
(LEUCOSPERMUM) CULTIVARS
K. Leonhardt, leonhard@hawaii.edu,
P. Shingaki, D. Oka, S. Ferreira, and N. Nagata
The pincushion protea
(Leucospermum) hybridizing program at CTAHR's Maui Agriculture Research
Center in Kula, Maui, was revitalized in 1994 with funding from a federal
floriculture research grant. A survey of growers helped to determine that
the breeding criteria would include resistance to root and foliar fungal
diseases, and improved horticultural characteristics such as a more vertical
plant growth habit, with long, straight and lightweight stems having small
leaves.
Since a breeding
program relies on the heritability and combining ability of genes for these
desired characteristics, the first step was to identify species and hybrids
with one or more of these desirable characteristics. Following that, a breeding
strategy was developed to involve a series of primary crosses, sibling crosses,
and back crosses. The crosses were made and in three to four months the
seeds were collected, sown, and germinated.
Plants were nursery
grown until about six to eight inches tall, then planted in irrigated fields
and grown for two years to first flowering. Upon first flowering the seedlings
were evaluated against the criteria for an improved commercial cultivar
and selected for possible introduction to industry, or selected for possible
future breeding, or kept for continued observation, or destroyed. Approximately
98% of all seedlings were destroyed following their first flowering.
Earlier research
by CTAHR determined that L. saxosum is highly resistant to Sphaceloma (Elsinoe
scab disease), and South African research reports it to have low susceptibility
to Phytophthora root rot. It would be a challenge to use this plant in breeding
since it has small flowers of poor substance on short stems, poor vigor,
and a plant growth habit that hugs the ground.
Research at CTAHR
had earlier determined that L. Rachel (UH hybrid #29), with parentage [L.
glabrum x (L. vestitum x L. lineare)], has the best combined disease resistance
ratings to Elsinoe scab, Drechslera leaf blight, and Botrytis leaf blight
diseases. Later we would determine L. Rachel to be one of our most reliable
stud plants for transmitting improved horticultural characteristics to its
progeny.
South African
research determined that L. Spider, (L. formosum x L. tottum), has some
tolerance to Phytophthora cinnamomi. It is used by many South African growers
as a root stock, on which other selected clones are grafted. Another South
African hybrid, T88-09-02, (L. cuneiforme x L. glabrum), has vigorous growth,
good plant structure and long stems, large and well formed flowers, and
apparent tolerance to root disorders. These, as well as other species and
hybrids, have been used in the breeding program with good results.
Since 1994, over
600 hybrids have been made and nearly 3000 seedlings have been evaluated.
About 70 plants have been identified for continued observation, or for use
in future breeding, or to increase for distribution of cuttings to industry.
In October 1999, CTAHR released seven new Leucospermum hybrids (over 1500
cuttings) to protea growers in Hawaii, as follows:
UH hybrid #72,
(L. Spider x L. T88-09-02). The blossoms have orange styles and red ribbons.
This plant is in bloom nine months a year.
UH hybrid #82,
(L. Rachel x L. saxosum). The blossoms have bright red styles and ribbons.
It appears to have some resistance to Elsinoe scab disease, but scientific
tests are not yet completed. Its young foliage is an attractive maroon red.
The blooming period is December through March.
UH hybrid #89,
(UH #58 x L. Tango). Styles and ribbons are deep red, with an attractive
white "frost" on the ribbons. This plant blooms almost year round. It is
one of our favorites.
UH hybrid #104,
(L. Ballerina x UH #31). This plant has slender stems and leaves. The blossoms
have dark orange styles and metallic ribbons. This plant is a heavy bloomer
from January through June.
UH hybrid #105,
(L. Ballerina x UH #31). Styles are orange and ribbons are blood red. This
plant is a heavy bloomer from January through June. It is a sibling of UH
#104.
UH hybrid #133,
(L. T88-09-02 x UH #49). Styles are dark yellow and ribbons are dark orange.
The blooming period is December through June.
UH hybrid #135,
(L. T88-09-02 x L. Spider). Styles and ribbons are yellow. Flower shape
is like L. Spider. This plant blooms heavily from November through June.
It was selected from a reciprocal cross of UH #72.
The information on yield and seasonality given above is based on plant performances
at the Maui Agriculture Research Center in Kula, Maui. Yield and seasonality
may be different at other locations.
Several new hybrids
will be introduced late in 2000, including the first time release of hybrids
involving the species L. reflexum. The influence of L. reflexum has produced
hybrids with very long stems and flowers with an architecture not previously
seen in Leucospermum. Flower shape is ovoid to globose when young, and as
the styles reflex with age the flower becomes a flat disk, larger in diameter
than any Leucospermum we have seen. The plants are also vigorous and high
yielding. These will be unusual new additions in the floral marketplace.
The next distribution
of new Leucospermum hybrids from CTAHR will be in September or October 2000.
Interested Hawaii growers can place orders with the Protea Cultivar Distribution
Foundation, at P.0. Box 425, Kula, Hawaii 96790.
WEED CONTROL OPTIONS IN LANDSCAPE BEDS
Jay Deputy, deputy@hawaii.edu
Department of Horticulture, CTAHR
Weed management in landscape
plantings is a complex task. The diverse nature of the ornamental plant
material and weeds present as well as differences in the size and slope
of the beds can create a big challenge. Herbicide options are limited by
the mixture of woody and herbaceous ornamentals, as well as health and environmental
concerns. Therefore, the integration of multiple strategies is necessary
to keep weeds from detracting from the beauty and quality of a landscape.
Weeds can be divided
into three general types--broadleaf, grasses, and sedges. Each type presents
its own special problems and often requires different control measures.
With the year-round growing season we have in Hawaii, all of these of weeds
can constantly become established in the landscape. For that reason, a continuing
year-round program is necessary to keep weeds under control.
Most of the common
broadleaf weeds that infest Hawaii's landscape are annuals, that is they
grow from seed, flower and produce more seeds, then die off within one growing
season. This process may take several weeks to several months or more. These
kinds of weeds are most likely to enter the cultivated landscape area by
seed dispersal from wind or birds. In Hawaii's year-round growing season,
most annuals do not exhibit a seasonal appearance. They do not undergo a
winter dormancy and are therefore able to exhibit a continuous life cycle,
presenting a constant problem.
Grassy weeds are
either annual or perennial. Perennial grasses live for many years. They
can spread by seeds like annuals, but creeping perennials also spread by
rhizomes or stolons. They are especially hard to control because of the
difficulty in completely killing all of the rhizomes and stolons. Popular
turfgrasses like bermudagrass and zoysia are warm season perennials that
often invade neighboring landscaped garden areas by sending "runners" into
the area. These types are more likely to be a continuing problem during
the warm summer months when they are actively growing. Repeated treatments
may become necessary to maintain a killed strip between landscape beds and
the turf. Quackgrass is a cool-season perennial and is more of a problem
during the cooler winter months in Hawaii. Quackgrass is also much more
likely to become established through dispersal of its seeds by birds.
Annual grasses
are easier to control. They are classified as summer or winter weeds based
on their emergence pattern. Both types tend to persist through out the year
in Hawaii. Summer annuals germinate more prolifically in spring, grow during
the summer months and then flower in late summer or early fall and gradually
begin to die off. Common summer annuals include large crabgrass in landscape
beds and smooth crabgrass, goosegrass, and smutgrass in turf areas. Winter
annuals tend to emerge more in the fall in Hawaii and persist through the
winter into spring and die off in the hot dry summer months.
Design and prepare the
ornamental planting bed with weed control in mind.
The ideal landscape according to a weed scientist might not win any awards
for diversity, but grouping similar plant material together allows for more
weed control options in the beds. Herbaceous plants, especially annual flowers,
are more sensitive to herbicides than ornamental shrubs or trees. In such
flower beds, mulching and hand pulling of weeds are often the only weed
control options. More herbicides are registered for use around woody ornamentals,
which also help shade out weeds that might otherwise germinate.
Certainly, a rich
variety of plant types and colors in a landscape are desirable and attractive,
but designers should at least consider the requirements for maintaining
the landscape over time. Before establishing a planting, evaluate the site
for soil type and slope and identify existing weeds so suitable plant material,
mulching and herbicide use can be selected. Control existing weeds with
a nonselective herbicide such as Round Up' or Finale' before the beds are
established.
Avoid introducing
weeds or their propagules (seeds, rhizomes) into the landscape, and eliminate
weeds that emerge before they begin to form seed. Root balls of field grown
nursery stock may contain tubers or rhizome fragments of perennial weeds,
which are then transplanted into the landscape with the shrubs.
Mulches are an effective
tool.
Mulches are commonly used in landscape beds to improve appearance, moisture
conservation and weed control. Mulches can control annual weeds but will
generally not control perennials. Mulches can be classified as organic (bark,
wood chips, composted leaves, pine needles), inorganic (crushed rock, crushed
coral, gravel) or synthetic (black plastic, landscape fabric). Mulches limit
light and physically block seedling growth.
As organic mulches
break down into finer particles, the mulch layer becomes a good growing
medium for weeds. Inorganic rock mulches will therefore usually give better
weed control than the organic mulches. Although natural inorganic mulches
like gravel or stone are generally more expensive than organic mulches,
they are stable over time, allow good water drainage and air flow and can
make very attractive mulches.
Coarse textured
organic mulches can be applied up to 4 inches deep and provide long-term
weed control. Fine-textured mulches pack more tightly and should be limited
to a depth of 2 inches. They degrade more quickly and consequently provide
weed suppression for a shorter period of time. The optimum mulch is relatively
coarse-textured with a low water-holding capacity. Because mulches rarely
provide complete weed control, pre-emergence herbicides can be applied to
improve the level of control.
Perennial weeds
such as bindweed, oxalis and plantain often have sufficient root reserves
to penetrate even thick mulch layers. Even annual weeds can grow through
mulches or germinate on top of a mulch as it decomposes. Weeds with wind
borne seeds such as horseweed, common groundsel and dandelion are most likely
to become established in the mulch.
Weed barriers can improve the weed control obtained with mulches.
Solid black plastic under a mulch dramatically improves weed control compared
to mulch alone. Black plastic has been used for years and provides excellent
control of annual weeds and suppression of perennials. However, nonporous
black plastic restricts water penetration and air exchange; thus, it is
not recommended for longterm use in landscape plantings.
Porous, black
landscape fabrics (geotextiles) have been developed to replace black plastic
in landscapes. Landscape fabrics form a barrier and block sunlight from
reaching weed seeds, but allow water and gas exchange necessary for plant
health. However, weed shoots can penetrate up through any openings in the
fabric and grass roots can penetrate down through openings in the fabric
if they are allowed to germinate on the surface of the mulch. Therefore,
the fabric should be free of rips, tares and other open spaces for maximum
weed control.
A key to the successful
use of fabrics is maintaining the mulch layer free of weeds, either by hand
weeding or the use of herbicides. Some brands of fabric, such as Biobarrier
II, contain a pre-emergence herbicide. Although relatively expensive and
labor intensive, landscape fabrics are cost effective if the planting is
to remain in place for several years.
Landscape fabrics
are most useful for longterm weed control around trees, shrubs and woody
ornamental plantings, but not for annual flower beds that are replanted
periodically or where a fabric could inhibit rooting and spread of ground
covers. Landscape fabrics can eventually be damaged by tree and shrub roots,
and pulling up a fabric may be difficult due to root growth within the material.
When installing
a fabric, first remove existing weeds and stones. Cut the fabric to fit
snugly around tree trunks and shrubs. For unplanted beds, cut an "X" in
the fabric for each planting hole. Avoid leaving soil from the planting
hole on top of the fabric since this will serve as a source of weed seeds.
After planting, fold the fabric back down to keep the sheet as continuous
as possible and secure to the rail with U-shaped pegs. Apply a thin layer
of organic or rock mulch on top of the fabric to prevent its destruction
by UV light (photodegradation). Remove any weeds that grow into or through
the fabric when they are small to prevent holes from forming in the fabric.
Landscape managers often use mulches in combination with herbicides to improve
the efficiency of weed control.
Some factors to consider
before selecting a herbicide are:
- What weeds are present and what weeds are expected to emerge? Are
the grassy weeds annual or perennial? Choose a herbicide or combination
of herbicides that will be effective on these weeds.
- What ornamental species are present in the planting? Is it safe to
over spray a grass herbicide? Be sure the herbicide is registered for
use on these species.
- How close are susceptible ornamentals and turf, and what is the risk
that they will be injured by the herbicide?
- What is the potential for residual effects of the herbicide on subsequent
plantings, especially those containing annual flowers?
- What precautions need to be taken to protect the applicator and property
owners?
- What method will be used to apply the herbicide (granular or spray
formulation)?
- How much will the treatment cost?
- How long will it take for the treatment to be effective and how long
will it last?
Herbicides are classified
according to their mode of action and the kinds of weeds they control. Some
classes of herbicides are effective either on grasses or broadleaf weeds
but not both. Many herbicides that are effective on grasses or broadleafs
are not at all effective on sedges. Therefore management strategies can
be very different depending on the species of weeds present and their location
within the landscape bed.
Pre-emergence herbicides
Pre-emergence
herbicides affect germinating seeds and are generally used to control annual
grasses and many broadleaf weeds. To be effective, this type of herbicide
should be applied several weeks before weed seeds would normally germinate.
In Hawaii, seeds are continually being disbursed and germinating, necessitating
a periodic application of pre-emergents throughout the year. Pre-emergence
granular materials may be applied with a fertilizer spreader. The spreader
must be calibrated to apply recommended rates. Compressed air sprayers or
sprayers attached to a garden hose are effective for liquid applications.
Pre-emergence
herbicides differ in the length of the residual effect and should be reapplied
accordingly. Some pre-emergence formulations are very volatile and must
be watered or cultivated into the soil for maximum effectiveness. Others
are ineffective if the soil is disturbed after application. Generally, herbicides
degrade faster under wet, warm conditions than under dry, cool conditions.
The dinitroanilines,
a group of pre-emergence herbicides including Trenan% (trifluralin), Surflan%
(oryzalin), Pendulum% (pendimethalin), Barricade% (prodiamine), and TeamPro%
(trifluralin+ benefin) inhibit root development in germinating seedlings.
They are most active on annual grasses, but also prevent the emergence of
some broadleaf weeds. Other pre-emergence herbicides for landscapes are
Devrinol%(napropamide), Pennant% (metolachlor), and Dacthal% (DCPA), all
of which prevent the emergence of annual grasses and some broadleaf weeds.
Pennant, in addition, has pre-emergence activity on yellow nutsedge. Others
are Gallery% (isoxaben), which controls a wide spectrum of broadleaf weeds,
and Goal%(oxyfluorfen) that has greater pre-emergence activity on broadleaf
weeds than grasses.
Additional choices
are available for annual grass and broadleaf control in woody ornamental
plantings. In addition to all the other pre-emergents, Casoron% (dichlobenil)
and Ronstar% (oxadiazon), and the combination products O-O%, RegalStar%,
Rout%, OHII%, and Snapshot% also control annual grasses. These products
are best for woody ornamental plantings because of their potential for injuring
herbaceous plants. Ronstar has greater pre-emergence activity on broadleaf
weeds than grasses.
Casoron controls
annual weeds and also certain perennial grasses such as quackgrass and tough-to-control
weeds like thistle, horsetail, oxalis, wood sorrel, and plantain. It can
be used around established woody ornamentals such as yews, arborvitae, and
juniper, but not around firs, spruces, or hemlocks. Casoron should be applied
during cooler weather and covered with mulch or watered in soon after application.
Of the herbicides registered for landscapes, Casoron is one of the best
for pre-emergence control of biennials and perennial weeds. Because Casoron
affects some turfgrasses, care must be taken to prevent the granules from
reaching turf areas when applying it to ornamental beds. Also, Casoron and
Ronstar should not be used in herbaceous ornamental beds.
Use the information
contained in herbicide labels and from your Cooperative Extension Service
to determine tolerance of ornamental plants to a given herbicide. Match
herbicides with weeds present and consider using herbicide combinations.
Combinations of herbicides increase the number of species of weeds controlled
and provide effective control of grasses and many broadleaf weeds. Commonly
used combinations include tank mixes of the materials discussed above in
addition to oxyfluorfen/pendimethalin (Ornamental Herbicide II), oxyfluorfen/oryzalin
(Rout), and oryzalin/benefin (XL).
Mulches can interact with herbicides.
The placement of an
herbicide in relation to an organic mulch can affect the herbicide's performance,
especially the pre-emergents. In addition, the specific characteristics
of the organic mulches can affect how herbicides work. A mulch that is primarily
fine particles can reduce the availability of some herbicides. The finer
the organic material (peat moss or manure, compared to bark), the greater
the binding of the herbicide. Most herbicides are tightly bound by soil
organic matter, less with mulches, and although the binding may minimize
leaching, it can also minimize the activity of the herbicide. Mulch that
is made up of larger, coarse particles will have little effect on the herbicide
activity.
A more important
factor is the depth of the mulch. An herbicide applied on top of a thin
mulch may be able to leach through to where the weed seeds are germinating,
but when applied to the top of a thick layer of mulch it may not get down
to the zone where the seeds are germinating. Products like oxadiazon (Ronstar)
and oxyfluorfen (Goal) that require a continuous surface layer must be placed
on the soil surface under the mulch. Most pre-emergence herbicides work
best when applied underneath the mulch layer. Such placement is possible
only if the herbicide is applied before the mulch is deposited or if additional
mulch is spread after herbicide application. Another reason to apply herbicides
under mulch is to reduce volatilization losses.
In general, the
pre-emergence products listed above, with the exception of Casoron, do not
control established perennial grasses. Pre-emergence crabgrass herbicides
do control perennial grasses germinating from seed, and some inhibit pegging
down of creeping perennials. However, to effectively control perennial grasses
in landscape beds, post-emergence herbicides should be used.
Post-emergence herbicides
Post-emergence
herbicides are used to kill weeds after the plants are up and growing. To
be effective, most post-emergence herbicides must be absorbed through the
leaves, therefore liquid sprays generally work better than dry granular
materials. However, granular formulations may be the most practical way
for homeowners to apply these materials. Post-emergence herbicides are effective
against perennial grasses and all broadleaf weeds. They are most effective
when applied to young and vigorously growing weeds. Post-emergence herbicides
generally provide minimal residual weed control, they are either inactivated
by binding to soil particles or rapidly degraded by soil microorganism.
The post-emergence
products that are available for control of perennial grasses and broadleaf
weeds include both selective and nonselective materials. Nonselective herbicides
kill all plants, including desirable ornamentals and turfgrasses, so extreme
care should be used when applying them. Selective post-emergence products
carry less risk of injury to desirable plants, and many can be applied directly
over the top of ornamentals and turf.
Selective post-emergence herbicides
The selective
grass control products, generally referred to as post-emergence grass herbicides,
are the compounds of choice in broadleaf ornamental beds due to their high
degree of safety to desirable plants. This group of selective herbicides
includes Poast% /Vantage% (sethoxydim), Fusilade%/Ornamec% (fluazifop),
Acclaim% (fenoxaprop) and Envoy% (clethodim). These products are systemic,
meaning they are taken up into the plant's system and affect the rhizomes
and stolons of perennial grasses. Repeat treatments are usually necessary
for longterm control of established grasses.
Members of this
class of herbicide only control grasses and have basically no effect on
most broadleaf weeds, sedges such as nutgrass and kyllinga, and other nongrass
monocots like wild onion and wild garlic. These herbicides must not be applied
over the top of ornamental grass or on many of the turfgrasses and care
should be taken to prevent drift into these areas when applying them to
ornamental beds.
Poast/Vantage
and Fusilade/Ornamec have been used extensively for annual and perennial
grass control in a wide range of herbaceous and woody broadleaf ornamentals.
These two herbicides are commonly used to control established Johnsongrass,
bermudagrass and quackgrass, tenacious weeds with few control options when
growing among ornamentals.
Acclaim effectively
controls annual grasses, with suppression of certain perennial grasses.
Envoy is the newest compound in this group, and less is known about ornamental
tolerances. However, it does control both annual and perennial grasses.
Sedges such as
nutgrass (purple nutsedge) and green and white kyllinga are perennials that
present their own special problems. They are not affected by most of the
grass or broadleaf herbicides, although the pre-emergent Pennant will control
yellow nutsedge. The most effective control for most sedges is with the
post-emergents Image (imazaquin) and Manage (halosulfuron). Both can be
applied over broadleaf ornamentals and turf areas.
Herbicide combinations
increase the weed control spectrum. Applicators may mix two of the "grass"
and "broadleaf" herbicides listed above or use one of the following granular
herbicide combinations: Rout% (oxyfluorfen+ oryzalin), Ornamental Herbicide
2% (oxyfluorfen + pendimethalin), Snapshot TG% (isoxaben + trifluralin),
Team or XL% (oryzalin + benefin). Product labels must be checked carefully
for lists of registered ornamental species.
Nonselective post-emergence herbicides
Roundup Pro% (glyphosate),
Finale% (glufosinate), Reward% (diquat) and Scythe% (pelargonic acid) are
nonselective herbicides which kill any plant they contact. All must be applied
only as directed or used as spot treatments in which ornamentals and turf
are not contacted. Reward and Scythe rapidly "top-kill" all vegetation contacted
by their spray, but perennial weeds can regrow. Finale is primarily a contact
herbicide, with limited translocation into the plant. Roundup Pro, a slower
acting herbicide, is readily translocated to roots and growing points of
plants, whereby it kills both annual and perennial plants.
Due to the potential
for nontarget injury, with any of these products but especially those that
translocate, extreme care must be taken when applying them around desired
plants. Shielded sprays minimize the potential for systemic injury.
It is important
to identify grassy and broadleaf weeds that infest the landscape beds you
maintain. Determine if they are annual or perennial and then develop a control
strategy that accommodates the ornamentals being maintained and the weeds
that need to be controlled. Depending on the situation, you may need cultural,
chemical or a combination of methods to control your weed problems.
Herbicide injury to established plants from soil applied chemicals is often
temporary, but can cause serious growth inhibition to newly planted ornamentals.
Herbicides that contain oryzalin or isoxaben are more likely to cause injury.
There are some methods available to remove herbicides from the soil, but
usually it just takes time for the herbicide to completely degrade. To speed
degradation, supplement the organic content of the soil and keep it moist
but not wet during periods of hot weather. Herbicide injury symptoms vary
according to plant species and the herbicide and can include yellowing (chlorosis)
and/or bleaching, root stunting, distorted growth, and death of leaves.
Sources:
"Weed control in landscape beds", Todd L. Mervosh, (Connecticut Agricultural
Experiment Station, Windsor)
"Manage grassy weeds in landscape beds", Jeffrey Derr (Virginia Polytechnic
Institute and State University)
"Weed Management in Landscapes" University of California Weed Management
Guidelines,1997
COMPUTER USE IN THE GREEN INDUSTRY
With only 12.9
percent of today's green industry professionals not using a computer in
their business, computer technology is becoming a daily element in landscape
contractors' jobs and these machines are serving a wide range of functions.
In a survey of
Lawn & Landscape readers, accounting and billing functions took the
No. 1 spot in 1998, with 77.5 percent of those surveyed stating this as
their purpose for computer use. At a fairly close second is word processing
(64.0 percent), with estimating coming in third at 44.9 percent.
Internet use is
one computer function for 41.6 percent of respondents, while landscape design
use was noted by 35.7 percent. Inventory and scheduling/routing finished
at 27.2 percent and 25.8 percent, respectively, and purchasing was the least
reported purpose with 15.2 percent.
IRRIGATION SHORT COURSE TO BE OFFERED IN MARCH
Tim Wilson, from
The Irrigation Association out of Fairfax VA, will once again give a series
of workshops on landscape irrigation. The series will cover individual sessions
on Installation and Maintenance, Hydraulics, Sprinkler System Scheduling,
and Drip Irrigation. This will be the fifth time that Tim has come to Hawaii
to conduct this very informative program.
The Oahu multisession
program will be held at The Pacific Beach Hotel and is cosponsored by Professional
Grounds Maintenance Society-Hawaii Branch (Crispin Bergantinos, Jr., president)
and Landscape Industry Council of Hawaii (John Wilkinson, president). Neighbor
island sessions will also be scheduled depending upon demand.
The exact date
has not been set, but will be sometime in March. Look for future announcements
in this news letter and also in Hawaii Landscape Magazine.
CREW SIZE SIGNIFICANCE
Crew size affects
productivity, and productivity affects pricing. An efficient crew size often
determines the company's bottom line down the road. Many contractors have
the exact crew chosen when they are giving the bid, while others wait until
they have the work.
"We solicit the
work then react to what we get," stated Tim Caw, president, Cardinal Lawn
& Landscape, Rochester, N.Y. "We use two-man crews the majority of the
time. For larger projects, sometimes the crews will merge," Dennis Barriball,
president, Hemlock Landscapes, Chagrin Falls, Ohio, explained that even
if they do have a crew in mind at the time of the estimate, it wouldn't
make a difference, "We run three maintenance crews, but our quality doesn't
change with the face of the crew.
He added that
they use two-man crews because it is more efficient, "The market won't bear
a supervisory position on a crew, a third person isn't economical," "We
have different crew structures for different jobs," commented Ray Bradley,
president, Raymow Enterprises, Oldsmar, Fla. "I never run more than a three-man
crew. Sometimes with large properties, I may divide it in sections for different
crews to get it done in a timely fashion."
From: Lawn and
Landscape Magazine, April 1999
PREVENTATIVE MAINTENANCE FOR PONDS
There are certain
steps a landscape contractor should take when building a water feature to
ensure it gets a clean start and to act as good preventative maintenance
practices.
Nutrient and Silt Control
- Do not fertilize grounds sloping toward the water. Fertilizer may
eventually end up in the pond.
- Dispose of wastes (leaves, grass, fish, entrails, garbage, ashes,
etc,) away from the water. All of these materials can serve to increase
the nutrient concentrations.
- Allow a "buffer zone" (strip of grass or natural vegetation) to grow
around the shoreline. This will help stabilize banks, reduce erosion,
provide an aesthetically pleasing landscape, and retain some nutrients
that would otherwise enter the water.
Shoreline Management
- Plant native vegetation that blends in with the surrounding to encourage
a diversity of wildlife.
- Protect shorelines from erosion and undercutting. Use rock lining,
terracing or seawalls,
- Fence out livestock or pets to prevent them from entering the water.
Fish Management
- Never randomly stock fish. Introduction of fish should be carefully
planned in terms of species, sizes and numbers according to the size,
water quality and production potential of the pond.
- Do not introduce rough fish (carps, suckers, etc.). Never discard
unused minnows or certain aquarium fish into the water. Watch for signs
of unbalanced fish populations such as overabundant small fish, too
many fish of one size class or undernourished fish.
- Do not over feed fish if a supplemental feeding program is used.
Excerpted from How to
Identify and Control Water Weeds and Algae, a 5" edition, revised 1998,
produced by Applied Biochemists, Milwaukee, Wis.
Publications databases
UH's agriculture
college and experiment station have been publishing for almost 100 years,
and the CTAHR Web site has a comprehensive database of that work. There
are three parts to the database. In one, you can find any thesis or dissertation
written by graduate students in the college's various departments since
advanced degrees were first granted in 1913. While these documents were
not published in the usual sense of the word, they are available in UH-Manoa's
Hamilton Library.
In the second
database are found titles of research articles published by the college
faculty. These articles were published not by the college but in various
books and academic journals, but each was given a "journal series" number
and recorded by the college. Journal Series offprints are stored in Hamilton
Library and the archives of the Hawaii State Library System.
While the journal
and thesis/dissertation databases are of interest mostly to scientists and
other scholars, the third database of the college's publications may well
contain "something for everyone." Its 7000-plus entries going back to about
1900 detail generations of research and extension effort by the college's
personnel. The database indicates which of the titles are still available
in print, and most of those still available can be obtained for free from
the CTAHR publications office. The titles that are out of print can be found
in Hawaii's libraries.
"Ask the Experts"
A new, developing
feature of the CTAHR Web site is called "Ask the Experts." This is a way
to record the knowledge of the college's experts so that people needing
answers to "frequently asked questions" (and some not so frequently asked)
can get the information without having to obtain a publication or contact
the expert in person. CTAHR faculty enter information into the ATE database
in the form of questions and answers. Users of the database search for particular
terms, and all questions relevant to those words are found.
Other information sources
While you are
at the "information table" at CTAHR's Web site, you may want to check out
several other sources available there.
How to get there
Not everyone has
a computer with Internet access, but most public libraries have such computers
available for the use of their patrons. You can direct the Web browser software
to one of the specific locations given above, but the best way to start
may be to go to the CTAHR "home" page. From there, you can click on "people,
publications, and databases" or "extension and outreach" to find the links
to reach the resources mentioned here, and much more.
DETECTION, TRANSMISSION, AND MANAGEMENT OF ORCHID
VIRUSES IN HAWAII
Dr. John Hu, johnhu@hawaii.edu
Dept. of Plant Pathology
There are more than
20 plant viruses that infect orchids. The most prevalent and economically
important viruses infecting orchids worldwide are Cymbidium mosaic virus
(CyMV) and Odontoglossum ringspot virus (ORSV). They occur wherever orchids
are cultivated as ornamentals and have been detected in most genera tested.
The virus infections cause a reduction in the quality and quantity of flowers
produced, resulting in economic losses. Infected orchid flowers are smaller
and fewer in number and may be deformed. Control of ORSV and CyMV infections
in orchids is difficult because the viruses are very stable and mechanically
transmitted between plants during handling and harvesting.
The Hawaiian orchid
industry is an important segment of the exotic, tropical, cut flower industry,
playing a significant role in the diversity of Hawaiian agriculture. In
Hawaii, seed propagated hybrid seedlings of Dendrobium orchids produced
at the University of Hawaii (Dendrobium UH hybrids) comprise about 75% of
State's propagated orchids. Effective control of CyMV and ORSV in orchids
will allow growers to improve the quality and quantity of orchid production.
Orchids are also popular in home gardens in Hawaii; orchid viruses are concerns
for orchid hobbyists.
The objectives
of this collaborative project with Dr. Steve Ferreira, Dept of Plant Pathology,
and Dr. Adelheid Kuehnle, Dept of Horticulture, at the University of Hawaii
are (1) to develop rapid and sensitive assays for the detection of orchid
viruses; (2) to study the transmission, movement, and management of CyMV
and ORSV; (3) to develop resistant transgenic orchids for control of CyMV
and ORSV; and (4) to characterize other orchid viruses in Hawaii.
Detection
Sensitive, rapid, and
reliable ELISA assays were developed for detection of CyMV and ORSV. An
indexing system for CyMV and ORSV has been established in Agricultural Diagnostic
Service Center, University of Hawaii (808-956-8053). A statewide survey
was conducted to determine the incidence and distribution of orchid viruses
in nurseries and farms in Hawaii. Approximately 3,600 orchid plants representing
44 genera from three orchid collections, twenty-two commercial farms, and
six nurseries on the islands of Oahu and Hawaii were surveyed. CyMV was
detected in 61% and ORSV was detected in 25% of 44 orchid genera surveyed.
Double infection with both viruses occurred in 20% of the genera. CyMV and
ORSV were detected in 29 and 7 of the 31 sites surveyed, respectively. When
330 cloned orchid samples were tested, CyMV and ORSV were detected in 45%
and 9% of the clones, respectively.
With Dendrobium
UH hybrid seedlings, only 4% of the 758 samples less than three years old
tested were infected by CyMV. Of 2381 UH Dendrobium hybrids more than three
years old, CyMV was detected in 94% of the samples in some farms, but only
2% of the samples from other farms, suggesting that clean plant sources
and sanitation approaches could be used to successfully manage CyMV. ORSV
was not identified from any of the commercially grown Dendrobium UH hybrids.
Recently, we developed
immunocapture polymerase chain reaction (IC-PCR) assays for detection of
CyMV and ORSV. These assays are much more sensitive than the ELISA assays.
Transmission
In order to develop strategies for management of orchid viruses, we conducted
transmission and movement studies of CyMV and ORSV. Transmission of CyMV
and ORSV to Dendrobium UH hybrids occurred readily. CyMV and ORSV were detected
from inoculated leaves as soon as 3 days after inoculation. CyMV moved systemically
from inoculated leaves to the entire plants within a month. However, ORSV
did not move systemically beyond the inoculated leaf. This observation could
account for our failure to detect ORSV from the UH hybrids surveyed. Porter
and Kuehnle at UHM found that CyMV was not transmitted from CyMV-infected
pod and pollen parents to 7,050 seedlings of Dendrobium UH hybrids (UH232
and UH503) and concluded that CyMV is not seed transmitted.
Management
We evaluated the following
seven compounds for their effectiveness of inactivation of CyMV and ORSV
for disease control: skim milk, Ivory liquid detergent, sodium hydroxide
(NaOH), Clorox (5.25% sodium hypochloride), Physan, Agribrom, and ethanol.
Skim milk, Ivory liquid detergent, Physan, Agribrom, and ethanol were ineffective
for inactivation of CyMV. NaOH at 1% concentration inactivated both CyMV
and ORSV and did not cause phytotoxic damage. Therefore, NaOH at 1% concentration
can be used to sterilize pruning tools to inactivate viruses.
Genetic Engineering
We cloned CyMV and ORSV and obtained the coat protein and movement protein
genes of CyMV and the coat protein and the 54 kDa putative replicase genes
of ORSV. We introduced the genes by the biolistic gene transfer technique
into leaf tissue of Nicotiana benthamiana and into protocorms and protocorm-like
bodies of Dendrobium orchids. Transgenic orchid and tobacco plants were
produced and are being characterized.
Other Orchid Viruses
Dendrobium mosaic virus
(DeMV) was first described in Hawaii 40 years ago. The virus induces chlorosis,
mosaic, and distortion of leaves and color breaking and distortion of flowers
in Dendrobium superbum Reichb. (known in Hawaii as the honohono orchid).
Using a polyclonal antiserum produced in this study against purified DeMV
particles, we found that DeMV is widespread in honohono orchids in Hawaii
but not in any other orchids. We cloned DeMV and obtained DeMV-specific
cDNA clones.
Sequence comparisons
of the coat protein amino acid sequence and 3' untranslated region showed
that DeMV shares 88-91% and 85-95% identity with those sequences of bean
common mosaic virus (BCMV) subgroup members, respectively. Results from
our host range studies suggest that DeMV is similar to other potyviruses
in the BCMV subgroup such as azuki bean mosaic virus and blackeye cowpea
mosaic virus. Based on these information, DeMV is now considered a member
of the BCMV subgroup.
We found TSWV-infected
orchids (Oncidium cv. 'Gower Ramsey') in a nursery on Oahu. We discovered
that the TSWV infection was localized to symptomatic tissues only. The growers
were able to contain the infection by removing the infected leaves from
approximately 8,000 Oncidium plants rather than destroying them, thereby
reducing economic losses.
In summary, CyMV
is very widespread in Dendrobium UH hybrid orchids in Hawaii, but ORSV is
not. Both CyMV and ORSV infect inoculated leaves well, but only CyMV causes
systemic infection on Dendrobium orchids. CyMV is not transmitted by seeds.
Skim milk is ineffective to prevent CyMV infection in Dendrobium orchids.
It is recommended to use virus free orchid plants (either Dendrobium UH
hybrid seedlings or indexed mericloned plants) to initiate a new orchid
nurseries or to replace old orchid plants, and to use sanitation practice
(e.g. use of NaOH at 1% concentration or flame to sterilize pruning tools)
in handling orchid plants. TSWV and DeMV were found in orchids in our survey.
Acknowledgments
This study was
supported in part by grants from USDA Federal Floriculture Project, USDA/CSRS
Special Grants in Tropical and Subtropical Agriculture (Section 406), and
Hawaii's orchid growers associations.
Dr. John Hu is
associate plant pathologist, Dept of Plant Pathology, College of Tropical
Agriculture and Human Resource, University of Hawaii at Manoa
EFFECTS OF ETHREL AND GIBBERELLIN ON IMPATIENS PLANTS
g. Tamari, L. Pappa, T. Zered, and A. Borochov.
Scientia Horticulturae 76:29-35, 1998
In many locations, impatiens
(Impatiens balsamina) flowers year round and maintaining stock plant quality
for cutting production requires techniques to inhibit flowering without
adversely effecting the number, length or rooting capacity of the cutting
material.
In this study,
combined treatments of ethrel and gibberellin were applied to two impatiens
cultivars - 'Tempo Pink' and 'Aruba' - in winter and in spring to see if
the cutting quality of the stock plants would be improved. Ethrel was applied
at a variety of concentrations ranging from 200 to 800 ppm and gibberellin
was applied at 25 ppm. The treatments were made as canopy sprays in the
afternoon.
In the ethrel
treatments for both cultivars, the number of cuttings increased as the concentration
increased with double the crop at the highest concentration (800 ppm). However,
the cuttings from the ethrel treated plants were shorter than those from
the untreated plants. Addition of the gibberellin treatment increased the
length of the harvested cuttings without increasing the number of flowers.
Biweekly treatments of ethrel combined with gibberellin produce good quality,
nonflowering impatiens stock plants.
Cuttings should
not be harvested in the 3 days following the treatments since large amounts
of ethylene are produced during that period and this might be detrimental
to the postharvest quality of the cuttings.
ENCOURAGING WATER CONSERVATION THROUGH THE
PRINCIPLES OF XERISCAPING
Ginny Meade
Encouraging Water Conservation
Through the Principles of Xeriscaping Ginny Meade Water is the essence of
life--it is our most important resource. World water supplies are being
increasingly contaminated with chemicals and waste as the world's population
continues to increase. Changes in climactic conditions, brought about by
ozone layer depletion, global warming, and weather phenomenon like El Nino,
are affecting percentages of precipitation worldwide. As a result, the amount
of usable water is rapidly diminishing.
In Hawaii, water
supply is an especially fragile commodity. While we have abundant rainfall
in some places, the total area is small, thus limiting the total amount
of fresh water. Because of the porosity of the volcanic rock that makes
up most of our land mass, damming streams and rivers would be pointless;
the water would simply drain away. However, we do have a supply of fresh
water underground, due to a phenomenon known as the Ghyben-Herzberg Principle.
The slightly lower density of fresh water causes it to float on top of salt
water. When rainfall seeps into the porous volcanic ground, it forms a lens
of fresh water beneath the islands. Some of this fresh water is lost through
leakage into the ocean. Fortunately, most is dammed by underground volcanic
dikes, which flow vertically into the ground and hold water in the areas
of the lens. The amount of annual rainfall, critical for the constant renewal
of our fresh water supply, has been decreasing in recent years.
Hawaii's landscape
is made up of many microclimates and soil types. Many of these areas are
extremely arid. What makes a locale arid is not how much rain falls, but
how much accumulates in the soil. In developed and populated areas, where
native growth has been removed or reduced, landscaping and gardening are
important for water conservation. Intelligent and creative landscaping techniques
can not only increase the amount of water seeping into our water table,
but can also reduce the operational costs and consumption of water through
the use of mulches, low water use plantings, and limiting of turf areas.
Attractive landscaping is an essential element for both property value and
aesthetic appeal.
A water thrifty
idea that has developed over the past ten years is the concept of xeriscaping,
which is defined as "water conservation through creative landscaping". It
is important to fully understand the concept in order to sell it to the
general public.
Although the idea
has been around for a few years, xeriscaping is not yet a readily accepted
concept. In spite of growing water shortages and rising rates, investment
of time or capital on water conservation is "a tough sell". The word conjures
up visions of dry, dusty cactus and rock landscape, while most property
owners prefer lush and green. But wise water use doesn't have to mean brown.
One effective method for "selling" the idea is to produce a list of drought
tolerant and low water use plants. Many of the plants on such a list may
come as a surprise to the uninitiated. It is equally important to make sure
that the client understands the plants that will work in a xeriscape. One
suggested way to describe them is to use the terms "water spenders", "water
savers", and "drought avoiders". Keeping the vocabulary clear will not only
help the client understand how the plants work, but will also avoid future
misconceptions regarding specific plant performances.
The term Xeriscape
has been adopted nationwide, and a concise set of principles has been devised:
- Start with a good design
- Improve the soil
- Limit lawn area
- Irrigate efficiently
- Choose appropriate plants for the area
- Practice good maintenance
The key to a satisfying
xeriscapic garden is planning and evaluation of existing conditions. For
a new installation, a design should work best with wind, sun, rain, and
topographical conditions in the area. Before making any plans, it is wise
to tour the neighborhood. Note which plants are working well in the area,
and which are not. Observe how much time surrounding properties require
for maintenance, and determine how much the prospective client is willing
and able to spend. Consider the path of the sun over the area, and any existing
structures that cast a permanent shadow. Windows reflect sunlight and heat.
Existing trees create shady areas where only shade loving plants will flourish.
Trying to change the natural inclination of a plant often leads to frustration
and failure.
Wind plays an
important role in plant growth and development. Air movement is required
for healthy conditions, but high winds will tear large leafed vegetation,
and cause rapid evaporation of water. In high wind areas, plant either low
growing varieties or deep rooted trees and shrubs whose roots can obtain
water from lower soil levels. Small leaved allspice trees and mock orange
hedges work well, and can form a windbreak for other plants. Use natural
hills and berms for interest, or consider creating such areas by moving
earth or rocks into place.
Soil pH, soil
texture and nutrient content must be determined before any work is begun.
Appropriate amendments should be made before planting, and may often affect
plant selection.
Use of the planted
areas should be considered. For residential areas in particular, if children
or pets require a turf area for play, choose only as much area as is necessary.
Lawn grasses and turf require high water usage for irrigation, and a controversial
but persistent viewpoint is that they should be limited or entirely eliminated
whenever possible. There are many other interesting and attractive ways
to cover ground that is not planted with trees, shrubs, or flowers. During
the six-year drought in the Western U.S., many homeowners made drastic changes
in their gardening practices, such as replacing the back lawn with a patio
of flagstone and cobbles that proved to be a big water saver. Many types
of turf require more water per square foot than other landscape plants.
When the lawn is kept appropriately small, water usage often drops dramatically.
When selecting turf, choose appropriate varieties, drought tolerant when
suitable, and investigate wearability and maintenance requirements as well.
Core aeration and slow release nitrogen fertilization will also enhance
water conservation in turf areas.
If the area must
have turf, plan a mini-oasis close to the house, surrounding the lawn area
with the plants of the highest water use, then graduating away from the
area through transitional plantings with lower water requirements. The areas
farthest from the mini-oasis should be of the low water use varieties.
Irrigation can
then be designed for each area, plants with the same requirements occupying
the same areas. New installations of irrigation systems will be water efficient,
and existing irrigation methods can be inexpensively adapted for lower water
consumption. Wherever possible, drip irrigation should be utilized. However,
it is not a panacea for water consumption and many facets of the system
and the plant needs should be considered. Most often, a combination of systems
will perform the most efficiently.
Mulches are another
solution to the bare ground question. Gravel of various colors and sizes
can be used in lieu of grass. Light colored stones reflect heat, so keep
them away from living areas, but use them in driveways and other areas to
keep the ground cooler. The ideal color for gardens is terra cotta or brown.
Designs that mix light and dark gravel or coral in a pattern can be very
attractive between plants, or along walkways. Keep the size of the stones
or gravel down to chip size, as fist-size and above does not act as mulch,
but rather gives a safe harbor to slugs, snails, and other garden eaters.
Wood chips, clippings, nutshells, and compost are also good mulches. Weave
paths between fruit trees paved with crushed shells or coconut husks for
a goodlooking landscape effect. Mulch around trees and shrubs should be
three to four inches deep, to inhibit weed growth and reduce evaporation--both
of which save water. An added benefit is the protection of stems and trunks
from weed-eaters and mowing machines.
For areas that
do not get foot traffic, many low ground covers are virtually maintenance
free, and produce a lush green carpet with little water usage. Hearts and
Flowers, a succulent with fleshy, small leaves and brilliant red blossoms,
will cover bare ground in no time. It also creeps onto walls and cement,
so some edging may be in order. Once established, it grows well on its own
and holds moisture on the soil surface with its dense coverage. Ice Plant,
another exotic succulent, grows about eight inches high, but spreads out
many feet from each plant. Its thick leaves glisten in the sunlight.
Be aware, however,
that many of the drought tolerant plants go through a period of dormancy
when the plants are forced to use water very efficiently, folding their
leaves and appearing sparse and withered. This is the same response that
some turf grasses have to drought, and both will become rejuvenated with
rainfall. It is at this point that the irrigation methods and techniques
can be adjusted if desired.
Sometimes, native
plants will be the most effective water savers. However, the cultivated
environment is usually drastically altered from the original natural environment,
and natives growing in an altered ecosystem will not always work well. The
important point is to know the plant, understand its needs, and put it where
it will perform best. Natives in the landscape are an interesting new trend,
but careful thought, research when necessary and planning are the best tools
for a successful design.
To entice the
property owner into xeriscaping, offer Juniper species, Plumerias, Jasmines,
Magnolias, and Bougainvillea. Many Gardenia and Hibiscus species are all
relatively low water use plants. The Bird of Paradise can grow up to six
feet tall, and requires little water. For large trees, the Ironwood, Date
Palm, Fan Palm, and Wili Wili are all suitable. Citrus trees can provide
fragrance, shade, and edible fruits. Herbs can provide interest, fragrance,
hedges and ground cover, and culinary variety. Basil, rosemary, and dill
require very little attention after establishment, and some varieties can
last for many years in Hawaii's climate. Extensive plant lists have proliferated
since xeriscaping was introduced, and a compendium of tropicals suitable
for Hawaii would be a welcome addition.
Xeriscaping is
an essential concept that should be considered in all design projects. Water
conservation needs begin with the initial planning stage, and carry through
to installation and continued maintenance. Regardless of the area to be
landscaped, moist or dry climate, large or small area, the basic principles
of xeriscape will provide savings in water and improved use of the land.
Ginny Meade is
a 1997 graduate of the University of Hawaii (B.S. in Horticulture). This
article was written in April, 1996 as a term paper for Hort 350.
NITROGEN LEACHING IN GOLF COURSE PUTTING GREENS
Jay Deputy, deputy@hawaii.edu
Education Specialist, CTAHR
The fate of nitrogen
(N) applied to turfgrass is a concern of both turfgrass professionals and
surrounding communities in Florida. This is primarily because of the unique
combination of climate, hydrology, soils, mobility of soluble N, and management
conditions when turfgrasses (particularly sports turfgrass) are grown in
Florida.
For a number of
years we have been investigating the fate of N and other agrichemicals applied
under an array of controlled management conditions in Florida and have developed
"Best Management Practices" to minimize any potential adverse impacts (Cisar
et al., 1989). Practical N management techniques such as the use of controlled
release fertilizers, fertigation, and irrigation management have been shown
to provide quality turfgrass with little N leaching (Snyder et al., 1980;
Snyder et al., 1984; Snyder, et al., 1989).
Most recently,
we have participated in a national research program investigating environmental
impacts from managing turfgrass systems sponsored by the United States Golf
Association (USGA). As an offshoot of our project on the persistence and
mobility of agrichemcials applied to a USGA green, we installed a leachate
collection system in reconstructed USGA type greens at an existing golf
course in south Florida during a renovation of the course to assess agrichemical
mobility under "real life" play and management conditions.
The initial objective
of this study was to monitor the mobility of the major agrichemical used
during grow-in, N, during the establishment/maturation phase of newly sprigged
bermudagrass greens and to illustrate the usefulness of these monitoring
systems for assessing agrichemical and water management of golf course putting
greens.
Materials and Methods
Based on experience
with stainless steel lysimeters for collecting percolate from a USGA green
at the Ft. Lauderdale Research and Education Center (Cisar and Snyder, 1993),
we installed a modified version of that lysimeter into greens on a golf
course in south Florida that was undergoing some course layout modifications
during the summer of 1993. Lysimeters were installed while greens 2, 14,
and 17 were being constructed. The lysimeters were fitted with bottom drain
lines to permit passive drainage from the bottom of the collection chamber
to a percolate collection station on the back or side slope of each green.
The "rooting mix
over gravel" greens construction combination in use at each location was
reproduced in each lysimeter, thereby preserving the hydrological integrity
of the percolate collecting system. Lysimeter installation was completed
in July 1993 and did not cause any serious disruption of the commercial
greens installation. The lysimeters have no adverse impact on the management
or use of the greens.
Collection of
percolate water by golf course personnel was initiated in September 1993
during grow-in and continued through July 1994 when the greens were in play
and receiving routine management. The water samples were analyzed for NH4-N,
NO3-N, P and K. Data for NO3-N is reported herein.
Results and Discussion
In Florida, there
is often a very narrow window of time for completing golf course reconstruction.
This is due to member/player expectations, the economic considerations of
the loss of greens fee revenues, and of course, the uncertainty of weather.
Thus, superintendents are often under extreme pressure to get their respective
courses back in play.
It is a well recognized
practice to facilitate grow-in of bermudagrass through the use of frequent
and/or large application of soluble N initially after sprigging. However,
soluble N applied to sand soils is prone to leaching especially when the
turfgrass does not have complete cover with extensive rooting for nutrient
retrieval. Therefore it was not surprising to see relatively high concentrations
of nitrate-N being found in the percolate from each green early on during
the study when soluble N was applied to immature bermudagrass.
During the establishment
phase, the concentration of N in percolate was high and above the current
drinking water standard. With the onset of 1994, there was a switch to slow
release N sources and, as the greens matured, there was greater nutrient
retrieval capacity. By late January 1994, the nitrate-N levels began to
approach and dip below 10 mg L-1 in all three greens and stayed consistently
below the current 10 mg L-1 standard as normal greens fertility maintenance
was adopted. However, nitrate-N levels began to rise in green 14. Any ideas
why?
The answer turned
out to be a rather simple one. The superintendent decided to overseed green
14 due to concerns over poor bermudagrass growth during the winter on that
particular green as a result of excessive shade.. And what do you do to
encourage overseeding? Fertilize and water plentifully to ensure germination
of the overseeding which accounted for the spike in nitrate-N in percolate.
However, as the overseeding period ended and a change over to routine fertilization
in May 1994, the drop in nitrate-N concentrations in percolate fell off
sharply and below the 10 mg L -1 standard for green 14 as well.
Conclusions
Several concluding
points can be drawn from this field monitoring study. First, leaching of
N with percolate can occur during establishment period. While the superintendent's
main concern during this period will be for the wellbeing of the grass,
N leaching should be considered as well, and can be reduced by the inclusion
of prudent management such as the use of slow release fertilizers and efficient
irrigation.
Secondly, the
use of conservative strategies of slow release N fertilizers under routine
management, effectively reduced N leaching in actual golf course management
conditions. These field observations verified the many years of research
on ways to minimize N leaching from turfgrass and the development of BMP's
by the University of Florida turfgrass faculty.
Finally, this
study demonstrated the usefulness of the field monitoring system as an additional
tool for management decisions for both nitrogen fertilization and irrigation.
Managers could use the data from these lysimeters to evaluate the environmental
effect of fertilization rates and methods, and make modifications where
appropriate.
In addition, just
knowing the amount of percolate collected can be very useful. Such measurements
can be used to determine whether irrigation is excessive. Clearly, there
would be no N losses when no percolate is observed. Obviously, with Florida
rains and irrigation inefficiencies, a situation of no percolate is unrealistic.
However it is realistic to avoid over irrigation and a waste of valuable
nutrient elements. It's also economically and environmentally friendly.
Literature Cited
Cisar, J.L., G.H.
Snyder, and P. Nkedi-Kizza. 1991. Maintaining quality turfgrass with minimal
nitrogen leaching. Fla. Coop. Ext. Ser. Bul. 273. pp. 11.
Cisar, J.L., and
G.H. Snyder. 1993. Mobility and persistence of pesticides in a USGA-type
green. I. Putting green facility for monitoring pesticides. Int. Turfgrass
Soc. Res. J. 7:971- 977.
Snyder, G.H.,
E.O. Burt, and J.M. Davidson. 1980. Nitrogen leaching in bermudagrass turf.
2. Effect of nitrogen sources and rates. Proc. Int. Turfgrass Res. Conf.
4:313-324.
Snyder, G.H.,
B.J. Augustin, and J.M. Davidson. 1984. Moisture sensor-controlled irrigation
for reducing N leaching in bermudagrass turf. Agron. J. 76:964-969.
Snyder, G.H.,
B.J. Augustin, and J.L. Cisar. 1989. Fertigation for stabilizing turfgrass
nitrogen nutrition. Proc. Int. Turfgrass Res. Conf. 6:217-219.
Adapted from an
article by George H. Snyder and John L. Cisar, University of Florida
GREENHOUSE CONDITIONING AFFECTS LANDSCAPE PERFORMANCE
OF BEDDING PLANTS
J.G. Latimer and R.D. Oetting
Journal of Environmental Horticulture
16(3):138-142. 1998.
Cultural practices and/or
chemical growth regulators are commonly used during greenhouse production
to control bedding plant height. The ultimate goal is to control plant growth
and condition the plant to tolerate the stresses of shipping, marketing,
and landscape establishment. The carryover effects of these practices on
landscape performance are seldom examined even though landscape performance
effects customer satisfaction.
The objective
of this research was to evaluate the effect of individual cultural or chemical
methods of growth regulation on greenhouse growth and landscape performance.
The treatments
included: two fertilization rates, two irrigation treatments, two plant
growth regulators, and mechanical conditioning. The two water soluble fertilizer
treatments were 50 ppm nitrogen three times per week (Low N) and 500 ppm
nitrogen three times per week (High N). The two irrigation treatments were
ebb-and-flow irrigation and drought stress to wilt point for 2 hours. Chemical
growth regulator treatments were single applications of 500 ppm B-Nine (daminozide)
or of 45 ppm Bonzi (paclobutrazol). Mechanical conditioning was applied
by brushing the top one-third of the plants with a wooden bar for 40 strokes
twice a day.
These treatments
were applied to columbine (Aquilegia x hybrida 'McKana Giants'), New Guinea
impatiens (Impatiens x hybrida 'Agadoo'), marigold (Tagetes erecta 'Little
Devil Mix'), and ageratum (Ageratum houstonianum 'Blue Puffs').
In all four species,
the plants in the Low N treatment required more time to reach acceptable
size or quality. On the other hand, only the New Guinea impatiens had improved
performance with the High N treatment.
Drought stress
reduced the quality of marigold and ebb-and-flow irrigation produced very
succulent plants susceptible to transplant shock.
Mechanical conditioning
reduced height and the reduction did not persist in the landscape, but the
brushing often produced unacceptable levels of damage to leaves and flowers.
The B-Nine application
produced moderately shorter plants without adverse impact on landscape performance
in columbine and marigold; the treatment was ineffective on New Guinea impatiens
and persisted after planting in ageratum. The Bonzi application caused persistent
excessive height reduction in New Guinea impatiens.
Conditioning treatments
such as drought or low nitrogen which produce physiological stress had the
greatest negative impact on subsequent landscape performance. Rates of chemical
plant growth regulators (PGRs) must be carefully selected to avoid persistent
growth reduction in the landscape. Management of cultural conditions to
produce healthy vigorous bedding plants in the greenhouse provides the best
plants for optimum landscape performance.
RESEARCH MAY PREVENT LOCALIZED DRY SPOTS IN BENTGRASS
GREENS
When built and
maintained properly, USGA greens have provided excellent results over a
period of many years for golf courses in most regions of the United States
and the world. Sports fields have had similar changes.
Nevertheless,
through the years, a number of problems and questions have arisen in the
course of implementing the method and the way greens and sports fields are
maintained. After years of investigation, the USGA Green Section introduced
its Specifications for a Method of Putting Green Construction in 1960. The
method utilized sand as the principal component of the root zone mix to
provide adequate drainage and resistance to compaction, and incorporated
a perched water table in the profile to provide a reservoir of moisture
for use by the turf.
During the past
10 to 15 years, changes have occurred in the way greens and sports fields
are maintained and in the number of products and technologies that have
been developed. Play has increased, golfers have demanded closer mowing
and perfection in maintenance, new grasses have been developed that have
different maintenance requirements, and many more golf courses are using
recycled water or poor quality water sources for irrigation. A wide array
of organic and inorganic soil amendments has been introduced, and ideas
for new construction methods have been proposed. In addition to astronomic
changes, the cost of golf course and sports field construction has increased
dramatically.
It has been found
that construction of creeping bentgrass golf greens with topsoil mixtures
that contain 90 percent or more sand has led to the appearance of irregularly
shaped areas of wilted or dead turfgrass known as localized dry spots (LDS).
This hydrophobic condition was confined to the top 20 inches of soil in
the LDS areas. This peculiar condition coincided with the presence of an
organic coating on sand grains that was observed by scanning electron microscopy.
Turf managers
from ten golf courses in Georgia completed a 34-question survey pertaining
to management practices used on their respective greens. Dry spots occurred
at all locations surveyed and no correlation was observed between management
practices and the severity of LDS. No differences in soil chemical properties
were found, but water droplet penetration time was greater in the LDS areas.
Soil layering
affects water retention in sports turf soil profiles. Sports turf areas
are often constructed by placing a root zone soil mixture over coarse textured
layers such as sand or gravel. This soil layering creates a calculated perched
water table in the root zone that the grass can use over time, instead of
water just draining from the root zone.
Research was done
to determine the degree to which drainage and water retention in soil mixtures
were affected by properties of the underlying layers. Water retention in
a soil mixture layer was greatest when a gravel sublayer was used. The next
greatest water retention was documented when sand was placed over gravel.
Sand and soil sublayers resulted in the least water retained. The trend
in golf greens construction during the past three decades has been towards
putting greens with at least 90 percent sand and limited amounts of silt,
clay, or organic matter used in the mix. High sand based systems typically
have low cation exchange capacity (CEC) and high drainage. These systems
are prone to nitrate leaching and could possibly contribute to ground or
surface water contamination.
Clinoptilolite
zeolite has a high CEC and a large affinity for ammonium ions and water.
Sand plus this form of zeolite had a lowered concentration of nitrate and
ammonium in drainage water while the zeolite doubled the water retention
and increased CEC 200 fold. Nitrate and ammonium leaching was 86 and 99
percent lower than unamended sand. The greatest reduction of nitrogen leaching
was found from when the sand was amended with zeolite at the highest rate
in the experiment.
The nitrogen fertilizer
use efficiency was improved by 16 to 22 percent with the addition of zeolite
to sand, depending on nitrogen application rate. Amendment of sandy rooting
media with this type of zeolite promoted better fertilizer nitrogen uptake
by turfgrass, and reduced nitrogen leaching from a highly leachable sand
based soil system.
Adapted from an
article by Robert L. Morris & Dr. Dale Devitt in Southwest Trees &
Turf, Oct. '98
ALCA ANNOUNCES SPONSORSHIP OF GREEN INDUSTRY WEB
SEARCH ENGINE WWW.LANDSCAPESEARCH.COM
Herndon, VA, December
8, 1999 - ALCA recently announced its exclusive sponsorship of a new search
engine which contains searchable links to thousands of Green Industry related
web sites.
The search engine
was designed to give individuals searching for green industry related information
a resource where they may efficiently search and find the web content they
are looking for. The search engine is different from other more general
search engines in that only web sites that are related in some way to the
green industry are included. This limitation allows for much more efficient
searching and alleviates the frustration of retrieving irrelevant web sites.
"ALCA is excited
to be the exclusive sponsor of www.landscapesearch.com as we feel that the
search engine will truly maximize the internet for our industry by collecting
and disseminating information from one central location ", said Debra Holder,
ALCA Executive Director.
Green industry
related companies may submit their web sites to the search engine free of
charge by visiting the site and selecting the "Add Your Web Site" option.
Future plans for
the site include several new web based services geared towards landscape
contractors, suppliers and their customers and are slated for release during
the course of 2000. Further information will be posted on the site as services
are launched.
Advertising opportunities
are currently available and green industry related companies who are interested
may call the ALCA office at 800/395-2522 or go to for more information.
CERTIFIED LANDSCAPE TECHNICIAN PROGRAM UNDERWAY
ON THE BIG ISLAND
Jay Deputy, deputy@hawaii.edu
Education Specialist, CTAHR
The Hawaii Island Landscape
Association has been awarded a state Employment and Training Fund grant
to fund the training and testing of maintenance landscape professionals
in Hawaii. The national Certified Landscape Technician program is administered
by the Associated Landscape Contractors of America. The one-year pilot program,
which began May 1, will focus on the Big Island this year before going statewide
in 2000. The Program is currently coordinated from the HILA office space
in Keahole Ag Park in Kona. Coordinators, Garrett Webb and Diana Duff are
available in the office from 9-5 Tuesday through Thursday.
The first round
of 12 classes was recently completed. Classes for the fall will be conducted
in duplicate afternoon and evening sessions beginning on January 4. Afternoon
sessions will be held from 1-4 pm at the Mauna Lani Resort, evening sessions
will be held from 6-9 pm at Kealakehe High School. The coordinators are
working now to inform the public and those in the landscape industry about
the program and preparing a test site for the certification testing next
spring.
This new program
marks the first time that Hawaii has provided standardized training and
testing for gardeners. It is designed to benefit landscape maintenance personnel
by increasing their knowledge and skills in the field while establishing
standards to strengthen their professional image in the industry and the
community. The certification of gardeners will also help employers and consumers
evaluate the technical ability of the gardeners they hire. The goals of
the program are to develop a highly skilled workforce for the landscape
industry trained in practices designed to protect and improve the quality
of our Hawaiian environment.
Anyone is welcome
to take the training classes, however, certification is only available to
those with experience in the field. Certification applicants must be able
to verify having at least 2 years field experience in the landscape industry
or 1 year of field experience plus successful completion of a training or
education program in the landscape field. The Certified Landscape Technician
Program is not a state regulation or requirement. Certification is not a
substitute for a state landscape contractor's license or any state issued
pesticide license.
The cost for each
class is $25, except First Aid in the Landscape which is $35. A package
price for all 12 classes is available for $275. The price of the Certification
Test, which will be conducted once a year, is $150. Classes are taught in
classroom situations with outdoor and/or hands-on experience where possible.
Students should come prepared to take notes and do some problem solving
in class.
A brief description of the 12 classes is provided below.
Plant Identification
Describes characteristics and growing conditions of 60 landscape plants
Sodding Turf / Tree Planting
Calculating area for laying sod. Proper grading, preparation and installation
of rolled sod. Proper technique for planting trees including guying and
staking.
Basic Pruning
Basics of plant growth. Tools and techniques for pruning shrubs and trees.
Advanced Pruning
Review of proper cutting procedures. Study of tree systems and techniques
for large tree pruning.
Turf Maintenance Equipment
Review of safe use and maintenance for mowers, riding mowers, front deck
mowers, weed trimmers, edgers and blowers.
Irrigation Plan Reading and Parts Identification
Basics of landscape and irrigation plan reading, parts identification and
sprinkler head adjustment.
Irrigation Controllers and Pipe Repair
Basic irrigation electronics, programming controllers and pipe repair.
Truck & Trailer / Chain Saw Operation Advanced
Proper techniques for operating a truck and trailer. Safe operation, maintenance
and in-depth mechanics of chain saws.
Turf Management - Fertilizing and Aerating
Developing a nutrient management plan, core cultivation and verticutting
turf.
Pesticide Theory
Review of pesticide safety, reading labels and calculating application rates.
Pesticide Application
Practice applying pesticides and using proper safety and protection gear.
First Aid for Landscapers
Red Cross First Aid class with special emphasis on safety and first aid
for landscapers. Students can receive a Red Cross First Aid Certification
upon completion of this course by passing the Red Cross test.
Members of the landscape industry interested in registering for certification,
working as teachers, judges or volunteers of equipment or time to the program
are encouraged to call the HILA office in Kona. Anyone can call for more
information about the program at 326-9738 or write the Hawaii Island Landscape
Association, PO 1594, Kailua-Kona, HI 96745, or e mail to: hila@aloha.net.
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:
Jay Deputy or Kenneth Leonhardt
Department of Horticulture, University of Hawaii
3190 Maile Way, St. John 102
Honolulu, HI 96822-2279
(e-mail Jay Deputy, Kenneth
Leonhardt)
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.
Kenneth Leonhardt, leonhard@hawaii.edu
CTAHR Extension Horticulture Specialists
James C. Deputy, deputy@hawaii.edu
CTAHR Education Specialist
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Green - Seeds Co., Ltd.
81/10B Ho Van Hue Street, Phu Nhuan District, Ward 9, Ho Chi Minh City, Vietnam
Tel: +84 (8) 847 6901 - Fax: +84 (8) 844 1392 - Email: info@green-seeds.com
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