|Landscape, Floriculture, and Ornamentals News||
Date Last Edited: 08/10/2001
Hawaii Cooperative Extension Service
No. 4, November, 1998
TABLE OF CONTENTS
David Hensley, email@example.com
Kenneth Leonhardt, firstname.lastname@example.org
CTAHR Extension Horticulture Specialists
Kent Kobayashi, email@example.com
Dept. of Horticulture, CTAHR, Univ. of Hawaii
Contracts that Make $ense for Property Managers
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
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
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:
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, (firstname.lastname@example.org) 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.
David Hensley, email@example.com
Primo®, a plant growth regulator used widely on golf courses, is labeled for St. Augustinegrass, according to Dr. John Cisar, University of Florida (firstname.lastname@example.org). 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.
Novartis Crop Protection, Inc.
Augustine, extension publication, CTAHR
St. Augustine growth
responses to various plant growth retardents. University of
St. Augustine, extension publication, CTAHR
St. Augustine growth responses to various plant growth retardents. University of Florida.
Jay Deputy, email@example.com
Producers of hibiscus and other ornamentals face the challenge of producing a variety of blemish-free crops. Fortunately, under the special conditions of greenhouse/shadehouse production, there is a wide range of management techniques available for both fungal and bacterial disease control.
Exclusion by quarantine
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.
The specific control method which will be most effective depends upon the source of the pathogen.
Hawaii Pesticide Information Retrieval System Home Page, CTAHR
Pest management techniques for hibiscus disease, A.R. Chase, U. 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, firstname.lastname@example.org
Root systems of bougainvillea typically circle the interior of the container outside the rootball when propagated by cuttings. These roots are brittle and easily broken off or injured during transplanting. However, researchers at the University of Florida have shown that the application of latex paint containing cupric hydroxide (13 oz/gal) to the interior of the container resulted in a root system that remained within the rooting substrate thereby reducing the possibility of injury to the root system, and hence transplant shock.
When rooted liners were transplanted to one gallon containers, those liners rooted in Cu(OH)2-treated containers resulted in larger plants 91 days after transplanting compared to those liners rooted in non-treated containers. Faster growing plants would allow for earlier upcanning, earlier sale of a certain sized plant, or result in a larger plant by a certain date.
Controlling rooting-out of B&B stock during storage, U. of Rhode Island.
David Hensley, email@example.com
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.
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.
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.
Eileen Herring, firstname.lastname@example.org
Effect of pesticide-treated grass clippings used as a mulch on
ornamental plants. B.E. Branham and D.W. Lickfeldt. 1997.
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.
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.
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.
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.
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
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
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
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
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.
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.
Fresh weight. There were noticeable differences in the fresh
weights of the harvested plants at the end of the study, however (Table
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.
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, email@example.com
Researchers at the University of Connecticut have developed the first true yellow Impatiens wallerana. The research was funded by Bodger Seeds, South El Monte, CA. Bodger Seeds is now marketing several forms of the plant as the Seashell impatiens series.
The plant was developed by crossing the color gene from one of the many yellow-flowering impatiens species, such as I. capensis and I. pallida, with the compact habit of I. wallerana. When species are cross-pollinated, the results usually vary widely. Most impatiens interspecific crosses produce see that is not viable. The university researchers, however, employed techniques that ensure the seed embryos would germinate.
Seashell impatiens has a habit similar to common I. wallerana, but is somewhat more vigorous. It grows well in partial sun to full shade, and pinching increases branching, controls plant height, and stimulates flower production. The cupped, shell-like flowers are available in six colors: yellow, apricot (light orange), papaya (rose with an orange blush), passion (light salmon-rose), peach (soft salmon-pink), and tangerine (neon orange). According to Bodger Seeds, Seashell impatiens are excellent container plants that combine well in landscape compositions.
What patience grew--This spring, look for yellow impatiens, once thought impossible to breed, Ottawa Citizen.
Getting to the Root of the Matter
Dr. Mike Schnell
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.
There are two basic types of roots--nonwoody and woody.
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.
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 (firstname.lastname@example.org), James R. Feucht, and James E. Klett. 1989. Journal of Arboriculture 15(9):201-205.
How Loud is Loud?
David Hensley, email@example.com
What is a safe noise level for the operator of gas-powered landscape equipment such as mowers, trimmers, or blowers?
Safety levels are often arbitrary so it is difficulty to say what level of noise is "safe." The Occupational Safety and Health Administration ( OSHA) calculates thresholds above which employers must provide ear protection for exposed employees. OSHA uses a rather involved computation, taking into account noise levels as well as duration of exposure. Both are important factors for assessing risk to hearing. However, a time-weighted average of 85 decibels over an 8-hour day is a level OSHA generally considers harmful.
For a loose comparison, heavy city traffic has been measured at around 85 decibels. A vacuum cleaner at 5 feet can produce 80 decibels, and a blender can emit 90 decibels. Because duration of exposure is such a critical factor, you cannot judge risk by decibels alone. However, many times of landscape equipment clearly exceed 85 decibels.
Few federal or state regulations address noise standards for outdoor power equipment. In fact, few standardized tests to define power-equipment noise levels even exist, though the American National Standards Institute (ANSI) is doing some work in this area. Several cities and towns enacting noise ordinances aimed at lawn and garden equipment (especially power blowers) have used arbitrary noise standards. this legislation is meant to address noise as a nuisance, not a safety issue. Blowers have been banned in many localities. These requirements are usually far more stringent than safety concerns dictate.
It is the employer's responsibility to supply ear protection to employees if high noise levels call for it. Such requirements are sometimes ignore in the turf and landscape industry. However, prudent landscape workers wear ear protection as standard practice. After all, ear plugs or covers is not really a major inconvenience and can protect hearing in later life.
Production Methods Can Affect Transplanting of Trees
David Hensley, firstname.lastname@example.org
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:
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:
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.
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 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, email@example.com
In the past month, we have received 2 calls from golf course superintendents on Oahu with frit fly infestations causing significant damage to bermudagrass fairways.
The adult 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.
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.
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.
On the Web
Some web pages you might find interesting:
On turf and landscape, The Lawn Institute
On recent research in agriculture, US National Arboretum Floral &
Nursery Plants Research Unit
Free publications from UH-CTAHR
Knowledge Master, UH-CTAHR integrated pest management program
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
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.Top of Page