C O N T E N T S
KEN'S MUSINGS
BEST MANAGEMENT PRACTICES FOR URBAN TREES
SNA Student Paper: EFFECTS OF SOIL LEVEL AND FERTILIZATION ON PERFORMANCE OF CONTAINER LOTUS
SNA Student Paper: PRODUCTION OF SNAPDRAGONS IN A HIGH TUNNEL IN SOUTHEAST ALABAMA
SNA Student Paper: PREEMERGENCE CONTROL OF Marchantia polymorpha
SNA Student Paper: CONTROLLING LIVERWORT INFESTATIONS
SNA Student Paper: A NON-CHEMICAL ALTERNATIVE FOR WEED CONTROL IN CONTAINER NURSERY CROPS
SNA Student Paper: GROWTH AND FLOWERING RESPONSE OF CRAPEMYRTLE TO TREE SHELTERS
PLANT PATHOLOGY REPORT
UPCOMING EVENTS

DISCLAIMER: Please remember that all information presented is a summary of research and not an endorsement of any product or a recommendation of chemicals. The official labels from the manufacturing companies offer the legal and proper use and handling information for all products.


KEN'S MUSINGS

This has been a hectic month with hurricane activity taking top priority. With the many reports coming in on damage, it appears there was more structural damage with Katrina than Ivan or Dennis. Alabama people feel so fortunate compared to our neighbors in Mississippi and Louisiana that they are just thankful for relatively less damage.

ALNLA and ALFA are working hard with our legislators to make sure we get help from the TAP program so that our industry can get some assistance with clean-up funds. If you ever wondered why you should belong to your state nursery association, this is one great reason. Without a consolidated voice that speaks as an industry, your concerns often go unheard and you receive little attention. Cyberspace is hopping with your leadership in ALNLA and cooperative efforts from Louisiana and Mississippi to be sure the Green Industry is not passed over again when recovery help is extended.

KEEP RECORDS!!!! You will need to document your expenses for recovery with receipts and pictures. Keep track of hours, labor, materials and take before and after pictures so you can accurately document your recovery efforts.

Looking back to past hurricanes, we are now putting together training materials for landscape contractors who will be receiving money from the state for replacement tree plantings. Selection and handling of nursery trees, site analysis and design features and planting and maintenance specifications for replanting our urban forests are also included (see below). I went to a meeting in Florida to discuss the latest research available on successful planting in a hurricane region. They have been abused a great deal in the past 5 to 10 years and have learned some valuable lessons. Below is a list of these recommendations which will be posted permanently on our web site.

The rest of the topics for the month include research presented by our faculty and students at SNA. If you want any more information on these research efforts, please give us a call.


BEST MANAGEMENT PRACTICES FOR URBAN TREES

Best Management Practices (BMPs) for successful landscape tree establishment in the urban environment depends on the design, site analysis, tree species selection, and proper planting and maintenance. All these factors are interrelated. Compromises to any of the BMPs are cumulative and affect other establishment factors. Successive compromises result in stress to the tree with potential death or failure of the planting. Each factor will be highlighted separately but keep in mind that all factors are evaluated with attention to the other three factors.

Evaluation of the site to develop the design is the first step in a tree planting program. Once you know the restraints of the site and the design requirements, plants can be selected and planting and maintenance specifications written to meet the site limitations. The following points should be considered during the site evaluation and design process:

Best Management Practices for Successful Urban Tree Plantings Specifications for Tree Selection
Successful landscape plantings can only occur when high quality nursery stock is selected which has the proper limb structure and root/shoot ratio balance. Trees should be healthy, free of disease and insect pests, and the quality should be maintained during transportation from the nursery and throughout the planting process. The following check list offers “minimum” guidelines for selection of trees for the landscape.

Shade trees should:

  • Have a strong, straight central leader with no lateral branches greater than 2/3s the caliper of the main leader.
  • Have branches equally spaced around the central leader at least 6 inches apart. Each branch should have its own space.
  • Have a uniform canopy in shape from all sides and free of large voids.
  • Have trunks which are free from all cuts and scratches. There should be no more that 40% of the height which is clear of branches unless it is specified by the designer.
  • Have proper pruning cuts that are not flush cuts but pruned to the collar.
  • Have root balls in B&B plantings which are of the appropriate size (see below) and they should be firm with no loose movement between the trunk and the root ball when the trunk is rotated.
  • Have container roots which fill the entire container without having any root greater than 1/5 the tree caliper and no large roots in the upper 3 inches of media encircling more than 1/3 of the root ball. If kinked roots are less than 1/3 of the root ball, they can be pruned.
  • Have tree branches with good spacing and wide angles from the main trunk with no included bark.
  • Be smaller rather than larger. Plant 1.5 to 3.5 inch caliper trees unless instant effect is desired and good soil conditions permit a large planting. Smaller trees establish better in poorly drained, low oxygen soils. Standards for Various Container and Field Grown B&B Trees
    The following tables, taken from the American and Florida standards and grades for nursery stock, offer a guide to the MINIMUM acceptable industry standards for root balls and container sizes for field and container grown trees. When selecting trees from the nursery, be sure that the nursery stock meets or exceeds these guidelines.

    ROOT BALL SIZE STANDARDS
    Trunk caliper (inches) Minimum ball diameter on field grown shade trees Minimum root ball diameter on fabric container grown trees Minimum container size (gallons) Minimum tree height on standard trees Minimum tree height on slower grown trees Maximum tree height
    1 16 12 5 6 5 10
    2 24 18 20 10 8 14
    3 32 20 45 12 9.5 16
    4 42 30 95 14 10.5 18
    5 54 36 95 . . .
    The optimum tree size depending on your need for instant effect and your site requirements should fall between 1.5 and 3.5 inches in caliper.

    ROOT BALL DEPTH AND DIAMETER
    Root ball diameter (inches) Minimum root ball depth
    Less than 20 Not less than 75% of diameter
    20-30 Not less than 66% of diameter
    31-48 Not less than 60% of diameter

    Source: American Standard for Nursery Stock, ANSI Z60.1 published by American Association of Nurserymen, Washington D.C. The complete publication can be found on line at:
    http://www.anla.org/applications/Documents/Docs/ANLAStandard2004.pdf. The University of Florida developed their own grades and standards for minimum container size recommendations for trees grown in aboveground and fabric containers, http://hort.ifas.ufl.edu/woody/planting/americanstandard.htm.

    Caliper is measured 6 inches from the ground on trees less than 4 inches in caliper. Above 4 inches in caliper measure at 6 inch height; move to 12 inches above the ground to measure trunk caliper or diameter.

    BARE ROOT CALIPER, TREE HEIGHT AND ROOT SPREAD
    Caliper (inches) Average height range (feet) Minimum root spread (inches)
    .5 5-6 12
    .75 6-8 16
    1 8-10 18
    1.25 8-10 20
    1.5 10-12 22
    1.75 10-12 24
    2 12-14 28
    2.5 12-14 32
    3 14-16 38

    Example: If your tree is 2.5 inches in caliper the average height should measure between 12 and 14 feet and the root spread should be a minimum of 32 inches.

    BOX SIZE FOR TREES
    Box diameter Maximum caliper range (inches)
    20 1.25-2
    24 1.5-2.5
    30 2.5-3
    36 2.5-3.5
    42 3-4
    48 3.5-5
    60 4-6

    Source: American Standard for Nursery Stock, ANSI Z60.1 published by American Association of Nurserymen, Washington D.C. The complete publication can be found on line at: http://www.anla.org/applications/Documents/Docs/ANLAStandard2004.pdf. The University of Florida has developed their own grades and standards for minimum container size recommendations for trees grown in aboveground and fabric containers, http://hort.ifas.ufl.edu/woody/planting/americanstandard.htm.

    Caliper is measured 6 inches from the ground on trees less than 4 inches in caliper. Above 4 inches in caliper at 6 inch height, move to 12 inches above the ground to measure trunk caliper or diameter.

    Best Management Practices for Successful Urban Tree Plantings
    Planting and Maintenance Specifications

    Best Management Practices (BMPs) for successful landscape tree establishment in the urban environment depends on the design, site analysis, tree species selection, and proper planting and maintenance. All these factors are interrelated. Compromises to any of the BMPs affect other establishment factors and result in stress to the tree with potential death or failure of the planting. Each factor will be highlighted separately but keep in mind that all factors are evaluated with attention to the other three factors.

    Once the proper tree has been selected to fit the site and the landscape design, proper planting and follow-up care are required for the success of the project. The following points should be considered during the planting process:

    Maintenance Requirements for Successful Tree Planting

  • Trees provided with regular irrigation, 3 times per week, for the first growing season will stimulate greater root growth. Establishment period is about 6 months for each inch tree caliper (ex. 3” caliper = 18 month establishment period)
  • Two to three gallons of water is required for each caliper inch of tree. Irrigation is applied to the root ball. If root ball is wet, do not irrigate.
  • Pruning should have been done at the nursery. No pruning for the first year after planting. Pruning can inhibit root growth and establishment.
  • Maintain 8’ mulch area surrounding tree and limit traffic to prevent compaction.
  • No grass or weeds are allowed close to the trunk.
  • Inspect planted trees to be sure they were not planted too deep and root flare is distinctly visible.
  • Remember to remove all stakes after first year.
  • Pruning is required after year 2 to remove lower limbs to lift canopy and maintain central leader, limb spacing and arrangement of limbs on the central trunk. Proper pruning cuts are required, (no flush cuts!).
  • Trees respond to fertility after year one primarily to Nitrogen (N) at a rate of 3 to 5 pounds of N per 1000 ft. If phosphorus and potassium have been adjusted to a medium level or better, those nutrients should be sufficient. A split application of fertilizer in winter and again in mid June should result in maximum growth potential.

    Ken
    334-844-5484 Office
    tiltken@auburn.edu


    NOTE: The names of current graduate students at Auburn are highlighted in maroon.

    SNA Student Paper: EFFECTS OF SOIL LEVEL AND FERTILIZATION ON PERFORMANCE OF CONTAINER LOTUS

    By Daike Tian, Ken Tilt, Jeff Sibley, Fenny Dane and Floyd Woods

    Lotus is an impressive flowering rhizomatous, perennial, aquatic herb, which has a long history in the diverse cultures of the Orient. The plant is sacred in the Hindu and Buddhist religions. Sacred lotus has been cultivated in Asia for thousands of years and has been a prestigious crop in China for nearly 5,000 years. A developing and open world economy has led to increasing exchanges and meshing of cultures, ideas and horticultural treasures. With the exciting discovery of viable 2,000 years old lotus seeds, this plant has moved into the spotlight and the lotus industry is blooming in the world.

    Little research is available on nursery production of Nelumbo nucifera Gaertn. (lotus). ‘No1’, an unnamed seedling (medium sized, with few emerging leaves and flowers) was used in testing the effect of fertilization rates. Lotus rhizomes were divided and planted. After planting, all pots were filled with water. The application of soluble fertilizer increased growth parameters. One teaspoon of 20-10-20 (Pro•Sol) every 20 days was sufficient for good growth in a 15 gallon container. Two teaspoons increased root weight, number of propagules and number of expanded internodes but also stimulated proliferation of algae growth in the beginning stage. ‘Embolene’ (medium sized, with numerous leaves and flowers) and ‘98 Seed’ (large unnamed seedling with numerous leaves, few but large flowers) were used in examining the effect of container soil level on the growth of lotus. Containers half filled with soil worked better than those three fourths full. Treatments of fertilizer rate and soil level had little effect on the concentration of macronutrients but significantly influenced concentration of some micronutrients especially B in young leaves.


    SNA Student Paper: EFFECT OF COTTON GIN COMPOST AND PINE BARK SUBSTRATE BLENDS ON ROOT GROWTH OF TWO HORTICLTURE CROPS

    By Brian E. Jackson, Amy N. Wright, and Jeff L. Sibley

    Pine bark (PB) and peat (P) are two of the most common substrate components currently used in horticultural crop production. The supply, consistency, and cost of these materials has often been a concern for growers throughout the United States. These concerns have prompted the search for alternative substrates and substrate components that can be successfully utilized for quality crop production. Cotton is a major agronomic crop grown in the southeast United States. Cotton gin trash (CGT) is the term used to describe the by-products of the cotton ginning process that includes the leaves, stems, hulls, and some lint. Composted cotton gin trash (CGC) has been shown to be a useful substrate component for production of bedding plants, floral crops, and woody ornamentals.

    Frequently excluded from horticultural research, root growth and root system architecture are important factors influencing plant performance and survival. A healthy, functioning root system increases the surface area available for the uptake of water and nutrients. In addition, roots provide physical support, storage, and anchorage needed by plants. Understanding root growth and development is important to improving plant quality and production success.

    The objective of this study was to utilize the Horhizotron™ to evaluate root growth of weeping fig (Ficus benjamina) and ‘Hot Country’ lantana (Lantana camara Mill. ‘Hot Country’) when grown in various blends of PB and CGC. The Horhizotron provided a simple, non-destructive method for measuring root growth and development in various root environments and substrates, and it allows roots to be observed and quantified as they grow from the original root ball and penetrate into the surrounding substrate .

    Treatments were four substrate blends of milled PB and CGC that included by volume: 100:0 PB:CGC, 60:40 PB:CGC, 40:60 PB:CGC, and 0:100 PB:CGC. Pine bark substrate was used as the control. Dolomitic limestone was added where needed to achieve pH levels of 6.0. Weeping fig and ‘Hot Country’ lantana were removed from 3 gallon containers and placed in separate Horhizotrons on greenhouse benches at the Paterson Greenhouse Complex, Auburn University. Root balls of all plants were positioned in the center of each Horhizotron and each quadrant was randomly filled with one of the substrate blends to the height of the root ball. Plants were hand watered daily and fertilized once weekly.

    Root length and location in the quadrant profile were measured as newly formed roots grew out from the root ball and along the face of the glass quadrants. A transparent grid placed on the two glass sides of each quadrant allowed observation and measurement of the five longest roots on each side of the quadrant. Over the course of the study root measurements were discontinued when roots reached the end of the Horhizotron quadrant. Root development in all CGC blended substrates was considerable enough to firmly hold the substrates together when plants were removed from the Horhizotrons. The quadrant containing 100% PB shattered upon being pulled from the Horhizotron, a result of less root proliferation in that substrate. This experiment provides strong evidence that roots can grow effectively and vigorously in substrates containing CGC, facilitating successful establishment and production of horticultural crops.


    SNA Student Paper: PRODUCTION OF SNAPDRAGONS IN A HIGH TUNNEL IN SOUTHEAST ALABAMA

    By Brad E. Reeder, Wheeler G. Foshee, III and Raymond L. Kessler

    Cut snapdragons are a multimillion-dollar crop but there are very few growers in Alabama where direct marketing has great potential. This study examined the possibility of exploring that potential by the use of high tunnels which have been used extensively in Europe and the Middle East for production of vegetables, annuals, biennials, and other horticultural crops.

    High tunnels are covered with a single layer of six-mil polyethylene and are ventilated by manually rolling up the sides. There are no permanent heating or cooling systems in the high tunnel but water is supplied for drip/trickle irrigation. Pennsylvania State University has extensively investigated production of many horticultural crops grown in high tunnels (including snapdragons - Antirrhinum majus). Their high tunnel production system utilizes many of the traditional production methods of field plasticulture.

    Recent research has shown that snapdragons grown inside a high tunnel had longer stems than those field grown. The objective of this study was to evaluate preplant nitrogen (N) rates with a control release fertilizer and to determine optimum snapdragon spacing. A single high tunnel (21’x96’) was constructed utilizing the Pennsylvania State University design at the Wiregrass Research Station located in southeast Alabama. Plants were grown on black plastic mulched beds (18 inches) that were prepared with a mulch-bedder (Reddick Fumigants, Williamston NC) and underlain with Tee-tape (0.45 gpm/100ft) for irrigation purposes. Irrigation was applied once a week at a rate of 1.0 acre-inch.

    Total stem length and inflorescence length peaked at the 240 lbs. N/A rate with the Polyon 19-6-12. Stem diameter did not peak at this rate. The stem diameters from the 240 lbs N/A rate were only 0.1mm smaller than the 360 lbs. N/A rate and 0.2mm smaller than the 160 lbs N/A rate. The 3x4 inch spacing yielded longer inflorescence length, stem length, and larger stem diameter compared to plants in the 4x4 or the 4x5 inch spacing. Our system (growing three rows on each black-plastic row) would allow for the greatest number of snapdragons per square foot of bed space (in our high tunnel the yield would be 6,750 plants per planting in about 6-8 weeks).

    Samples from this experiment were delivered to three local florists for a non-replicated evaluation. All of the florists rated these snapdragons in the ‘excellent’ category and indicated that they would purchase comparable snapdragons if grown locally throughout the year.


    SNA Student Paper: PREEMERGENCE CONTROL OF Marchantia polymorpha

    by Adam Newby, James Altland, Charles Gilliam, Donna Fare, and Glenn Wehtje

    Liverwort (Marchantia polymorpha) is an increasing problem in container-grown ornamental production within the Southeast. Prostrate leaf-like structures of liverwort known as thalli create a mat over media surfaces in containers. Not only is liverwort unsightly, it can impede water and nutrient movement into the root zone. It thrives in low UV light, high fertility and high moisture environments. Since it is an emerging problem, little research exists on preemergence controls. There are promising new products for postemergence liverwort control, but preventing liverwort infestations would be more desirable.

    Full-gallon containers were filled with a 6:1 pine bark to sand substrate amended with 14 lb of Polyon 18-6-12, 5 lb of dolomitic lime, and 1.5 lb of Micromax per cubic yard. Twelve granular herbicides were applied at the recommended rate: Broadstar (150 lb product/A), Kansel Plus (100 lb product/A), OH2 (100 lb product/A), Pendulum 2G (200 lb/A), Regal 0-0 (100 lb/A), Regal Kade (200 lb/A), Regal Star (200 lb/A), Ronstar (200 lb/A), Rout (100 lb/A), and Snapshot (200 lb/A). Treatments were applied using a handheld shaker. After treatment, each replication was placed around a container of mature liverwort for inoculation. The study was conducted under 47% shade. Overhead irrigation was split into two cycles per day with a total of 0.25” applied.

    This study showed that Broadstar and Ronstar provide superior preemergence control of liverwort compared to the other herbicides tested. It should be noted that there are no preemergence herbicides registered for use in enclosed structures.


    SNA Student Paper: CONTROLLING LIVERWORT INFESTATIONS

    by Adam Newby, James Altland, Charles Gilliam, Glenn Wehtje, and Donna Fare

    Liverwort continues to spread throughout the Southeast as a weed problem in container-grown ornamental crops. Liverwort thalli can cover the entire media surface of a container and restrict water and nutrient movement into the root zone, as well as reduce the marketability of a crop. Propagation houses, shade houses, and other covered structures provide ideal conditions for liverwort.

    One herbicide with potential is quinoclamine which has been used as an algaecide in Japan for decades. It is produced as a 25% wettable powder. Quinoclamine has proven to be very effective on postemergence liverwort control, and it is safe on a broad range of ornamental crops. Previous research suggests that lower rates and spray volumes provide adequate postemergence control. The nursery industry in Germany has used diuron for liverwort control. Diuron is a substituted urea herbicide widely used in cotton production within the Southeast. It is highly active and inexpensive. The objectives of this study were to evaluate lower rates and spray volumes of quinoclamine than current recommendations and any interaction between rate and volume, as well as evaluate the effectiveness of diuron for liverwort control.

    This study was conducted at Auburn University. Liverwort was grown in full-gallon containers consisting of a 6:1 pine bark to sand substrate amended with 14 lb of Polyon 18-6-12, 5 lb of dolomitic lime, and 1.5 lb of Micromax per cubic yard. Postemergence treatments were applied when liverwort covered at least 60% of the container surface. Diuron 4L and Linuron (another substituted urea herbicide with similar chemistry to diuron) 4L were each applied. All treatments were applied with a CO2 backpack sprayer fitted with an 8004 flat fan nozzle at 30 PSI. A non-treated control group was maintained. In addition to liverwort, all treatments were also applied to 6 single pot replications of Humata tyermanii (Rabbit foot fern) and Euphorvia pulcherrima (Poinsettia). The study was conducted in a temperature controlled greenhouse under 0.25 inch overhead cyclic irrigation per day split into two cycles.

    Main effects of quinoclamine rate, volume, as well as the interaction thereof were found to be significant. In general, control increased as rate and spray volume increased. Among quinoclamine treatments, higher spray volume provided greater control with lower rates. Conversely, lower spray volumes (54 gal/A) can provide adequate control at higher rates (1.0 and 2.0 oz product/A). By 70 DAT, 2.0 oz product/gal applied at 54 and 109 gal/A had the least percent liverwort coverage among the quinoclamine treatments with 40% and 22% coverage. All other quinoclamine treatments had a higher percentage of liverwort coverage. Quinoclamine treatments were compared to Diuron and Linuron treatments as well as the non-treated control group. No injury was recorded on Humata tyermanii or Euphorvia pulcherrima at any time throughout the study.

    The research data showed that quinoclamine rate and volume of application influence postemergence liverwort control. Rate and spray volume may best be determined by individual growers. This study also recognizes Diuron as a promising treatment for liverwort with excellent long term control.


    SNA Student Paper: A NON-CHEMICAL ALTERNATIVE FOR
    WEED CONTROL IN CONTAINER NURSERY CROPS

    By Ben M. Richardson, Charles H. Gilliam, Glenn R. Wehtje, Glenn B. Fain

    Container nursery crops are among the most valuable crops produced in the Southeast. Weeds can reduce the value of nursery crops by reducing growth through competitive effects and reduced salability due to consumer demand for weed free crops. Growers primarily use preemergence herbicides for weed control. However, demand has increased for nursery crops grown in large containers. Preemergence herbicides are often impractical as the increased spacing between containers results in over 50% of the herbicide falling outside of the containers. Hand weeding is another expensive option and and labor costs continue to increase.

    Fresh pine bark nugget mulch could be an alternative. It has been used for many years in landscape beds to control weeds and could be an option for use in container crops. Physical properties of fresh pine bark are conducive to weed control as it is hydrophobic with limited water holding capacity due to the large particle size. Pine bark is well suited to be spread uniformly as a mulch, covering the entire surface of the container while other mulch type products may leave cracks for weeds to establish. What needs to be determined is whether it can be effective for weed control; and the depth of mulch required for that purpose.

    These studies were conducted in Auburn, Alabama. Crapemyrtle (Lagerstroemia x ‘Acoma’) were transplanted from trade gallon containers into 7 gallon containers. The substrate used was a 6:1 (v:v) aged pine bark: sand amended with 2.3 kg (5lb) of dolimitic lime, 6.4kg (14lb) of Polyon 18-6-12. and 0.68kg (1.5lb) of Micromax. All plants were potted to equal depths, approximately 3 inches below the top of the container and were irrigated twice prior to treatment. Three treatments consisted of broadcasting 25 bittercress (Cardamine hirsuta) seed on the surface of the substrate of each container, then coarse pine bark nugget mulch was hand applied at 0, 1.5 and 3 inches respectively. The nuggets averaged in size from 0.79 in to 2.36 in flakes. Two other treatments consisted of first applying mulch at 1.5 or 3 inches, then broadcasting the bittercress seeds on top of the mulch. These procedures were also applied to five more treatments and a granular herbicide (Broadstar 0.25G at 150 lb product/A) was applied after all mulch and seed were present.

    In a similar study, common gardenia (Gardenia jasminoides) were transplanted from trade gallon containers into 7 gallon containers. The same treatments were applied to the gardenia except 25 oxalis (Oxalis stricta) seed were used per container instead of bittercress. In both studies, data collected were weed number per container at 30, 60, 90 and 180 days after treatment (DAT) and percent coverage of weeds at 60, 90, 180 DAT. These studies show that pine bark mulch can provide effective weed control for nursery crops grown in large containers. At 180 DAT oxalis was present in the no mulch, no herbicide treatment which contained 3.9 weeds and averaged 35 % coverage of container surface. All other treatments resulted in minimal oxalis growth . The combination of mulch plus herbicide provided complete oxalis control 180DAT.

    At 180 DAT bittercress was growing vigorously in the control containers (no mulch-no herbicide). These containers averaged 8.1 bittercress, 100% coverage of container surface and 59.6 g of bittercress per container. In comparison no herbicide, 1.5 inches of mulch treatment with seeding after mulching, averaged 2.6 weeds, 44% coverage of container surface and 33.7 g per container. Both treatments resulted in greater bittercress growth than all other treatments. Similar to the oxalis study, the combination of mulch plus herbicide provided complete bittercress control 180 DAT and no herbicide or mulch application affected growth of crapemyrtle or gardenia.


    SNA Student Paper: GROWTH AND FLOWERING RESPONSE OF CRAPEMYRTLE TO TREE SHELTERS

    By Kevin M. Brooks, Gary J. Keever, Jeff L. Sibley and James E. Altland

    Our research shows that the use of tree shelters in the production of tree-form crapemyrtles can increase height growth while minimally affecting caliper growth. ‘Dynamite’ and ‘Potomac’ were 124% and 61% taller at the end of the season when grown in tree shelters, while height growth of ‘Tuscarora’ was not affected by tree shelters. Caliper of sheltered and non-sheltered ‘Tuscarora’ and ‘Dynamite’ were similar at the end of the season, while caliper of ‘Potomac’ was 35% less when grown in shelters. Tree shelters may provide growers with a low-input way to accelerate production of tree-form crapemyrtles.

    Crapemyrtle are vigorous growers under nursery conditions; however, most cultivars begin flowering by early summer, resulting in a reduction in vegetative growth rate, particularly growth in height. This problem is often compounded by heavy fruit set later in the growing season. Pruning of inflorescences is labor-intensive and results in rapid re-bloom. For production of standard (single trunk) or multi-trunk (usually 3) tree-forms of crapemyrtle with a central leader and four to six feet of clear trunk, pruning exacerbates the problem by stimulating new shoot formation, often from the main trunk. Flowering and heavy fruit set can result in longer production cycles.

    Tree shelters, translucent tubes placed around tree seedlings, create a beneficial microclimate within the shelter of increased humidity and CO2 levels and reduced drying and mechanical damage from wind. Growth increases of 60 to 600% from using tree shelters have been reported. Shelters can typically increase height growth but reduce the rate of trunk diameter growth which may result in trees without enough structural support to stand upright. Tree shelters have been broadly used in Great Britain and other countries to cut costs of establishing small forest and landscape trees.

    Blue-X tree shelters (McKnew Enterprises, Elk Grove, CA) are fabricated from partially transparent blue-tinted polyester film and that amplifies blue light and reduces UV light within the shelter. According to the manufacturer, the amplified blue light increases photosynthetically active radiation resulting in increased trunk diameter in addition to accelerated growth in height and enhanced transplant survival. The objective of this research was to determine the effects of Blue-X tree shelters on height and caliper growth of tree-form crapemyrtle, with a goal of shortening the production time.

    ‘Dynamite’ grown in Blue-X tree shelters were consistently taller than non-sheltered trees: 118%, 128%, and 124% taller in August, September, and October, respectively, than controls. Calipers of ‘Dynamite’ in shelters and controls differed in early to mid season but not at the end of the season. In July, 30% of the ‘Dynamite’ controls were flowering while none of the trees grown in shelters had begun flowering. Height growth of ‘Potomac’ was also promoted by shelters, with trees grown in shelters 61% taller than the controls at the end of the season. Caliper growth for non-sheltered ‘Potomac’ was 35% greater than those with shelters at the end of the season. By August the ‘Potomac’ controls had flowered but not the sheltered trees. Height of ‘Tuscarora’ was not influenced by the Blue-X tree shelters, whereas caliper was 47% less in July when grown in shelters. However, by the end the season, calipers were similar for trees in the two treatments. ‘Tuscarora’ exhibited similar flowering characteristics as the other two cultivars in response to the treatments, with trees grown in the shelters flowering later than the controls. No cultivar had any flowering inside the tree shelters.

    Blue-X tree shelters significantly increased height growth in two of the three cultivars tested without affecting caliper at the end of the season. Growing crapemyrtles in Blue-X tree shelters may shorten production time by enhancing height growth.


    PLANT PATHOLOGY REPORT - JULY 2005

    Jackie Mullen, Extension Plant Pathology Specialist-Auburn
    Jim Jacobi, Extension Plant Pathology Specialist-Birmingham
    Charles Ray, Research Fellow IV-Auburn

    Auburn Plant Disease Report-July 2005 (J. Mullen)
    Many of the 267 July plant samples were ornamentals submitted by the State Department of Agriculture. These plant submission were part of a state and national survey of nurseries to detect Phytophthora ramorum (Sudden Oak Death). Forty-eight ornamental samples were submitted from nurseries by State Department of Agriculture Inspectors in July; 198 total samples were submitted from Nurseries (May 9-July 22). These samples were tested using visual study, microscopic study, and ELISA testing for Phytophthora. For all ELISA positive samples (There were none in July, 47 total nursery samples; 51 total samples), the DNA was extracted and sent by overnight mail to the USDA Beltsville molecular lab. PCR analyses were performed and results were sent to the Alabama State Plant Health Director (USDA-APHIS). From USDA-APHIS in AL, results were forwarded to the State Plant Regulatory Official and our lab. The State Plant Regulatory Official contacts the Inspectors who communicate with the growers. So far we have results back on 21 nursery samples, and all 21 analyses have been negative. It is too hot right now to sample for P. ramorum, but more survey work is planned for this fall.

    The above procedure was also followed by Inspectors when homeowner sample testing was requested. In total we tested 41 homeowner samples. Six samples were tested in July and none tested positive for Phytophthora using ELISA. (Four samples in June tested ELISA positive for Phytophthora; PCR results were negative for all four for P. ramorum.) This fall we hope more homeowners will request testing when they observe symptoms. If calls come to Extension offices, and appropriate, suspect samples are described, please forward client names and contact information to the State Department of Agriculture at tjohnson@agi.state.al.us.

    Rust was confirmed on kudzu in Baldwin County in early August and Conecuh County on 8/24/05.

    Other diseases of note in July include bacterial leaf spot on azalea, Fusarium solani stem rot and wilt on chrysanthemum, bacterial wilt on pepper, and tomato spotted wilt on zinnia. Anthracnose has been a common leaf spot disease on camellia and some other ornamental shrubs. Bacterial leaf spots have been common on a number of plants including azalea, cottonwood, lotus, maple, kudzu, and oak. Exact identification will be made shortly by the gas chromatography method.

    July Plant Diseases Seen in the Auburn Plant Diagnostic Lab
    PLANTPROBLEMCOUNTY
    AshAnthracnose (Colletotrichum)Jefferson
    AzaleaAnthracnose (Colletotrichum)*(2)
    AzaleaBacterial Leaf Spots*(4)
    AzaleaPhytophthora Leaf Spots*
    BermudaSpring Dead Spot
    (Gaeumannomyces,
    graminis
    var. graminis
    Jefferson
    BoxwoodMacrophoma Crown RotLimestone
    BoxwoodVolutella BlightLimestone
    CamelliaAnthracnose (Colletotrichu)*(7), Tuscaloosa
    CamelliaBacterial Leaf Spot*
    ChrysanthemumFusarium solani
    Stem Rot & Wilt on Mum
    *
    CottonwoodBacterial Leaf SpotHouston
    Crape MyrtleBotrytis DiebackTuscaloosa
    DogwoodCercospora Leaf SpotMarengo
    HollyAnthracnose (Colletotrichum)*
    KudzuBacterial Leaf SpotAutauga, Choctaw,
    Clarke, Marengo,
    Wilcox
    KudzuSeptoria Leaf SpotChoctaw, Henry,
    Jefferson, Marengo,
    Tuscaloosa, Wilcox
    LeucothoeAnthracnose (Colletotrichum)Tuscaloosa
    LotusBacterial Leaf SpotCullman
    MapleAnthracnose (Colletotrichum)*(4)
    MapleBacterial Leaf Spot*
    MaplePhyllosticta Leaf Spot*
    OakAnthracnose (Colletotrichum)Baldwin, Talladega
    OakBacterial Leaf SptosBaldwin
    OakFusiforme Rust (Cronartium
    quercuum
    var. fusiforme)
    Baldwin, Jefferson
    OakPhyllosticta Leaf Spot*
    OakPowdery Mildew*
    Oak, ShumardBacterial Leaf Spot*
    Oak, ShumardFungal Canker*
    PierisAnthracnose (Colletotrichum)*
    ViburnumAnthracnose (Colletotrichum)*(6)
    ZinniaTomato Spotted Wilt Virus*
    ZoysiaRust (Puccinia sp.)Colbert
    ZoysiaSlime Mold (Physarum)Lee
    ZoysiaTake-All Patch (Gaeumannomyces
    graminis
    var. graminis)
    Jefferson
    *Counties are not reported for nursery, greenhouse, and golf course samples.

    Monthly Plant Problem Report From The Birmingham Lab (J. Jacobi)
    We received 129 plant samples during July. Problems seen last month included Pythium and Rhizoctonia root rot on ajuga, bacterial leaf spot and Phytophthora root rot on chrysanthemum, downy mildew on coleus. Downy mildew on coleus was a new disease, not previously reported in Alabama. Foliar symptoms included angular necrotic spots, with a dense covering of gray-brown cotton-like mycelial growth. This fungus also attacks other hosts, including salvia.

    JULY 2005 Plant Diseases Seen In The Birmingham Plant Diagnostic Lab
    PLANTPROBLEMCOUNTY
    AjugaPythium Root RotTuscaloosa
    AjugaRhizoctonia Root and Crown RotJefferson
    AzaleaAzalea LacebugShelby
    AzaleaPythium Root RotShelby
    BentgrassAnthracnose*(2)
    BentgrassBrown Patch (Rhizoctonia zeae)*
    BentgrassPythium Root Dysfunction*(2)
    Boxwood, CommonBoxwood MitesJefferson, Shelby
    Boxwood, CommonLeaf MinersJefferson(2)
    Boxwood, CommonMacrophoma Leaf BlightJefferson(2)
    Boxwood, CommonVolutella BlightJefferson
    ChrysanthemumBacterial Leaf SpotBibb
    ChrysanathemumPhytophthora Root RotBibb
    ColeusDowny Mildew (Plasmopara)Jefferson
    Crape MyrtlePowdery MildewTuscaloosa
    Cypress, LeylandPhytophthora Root RotJefferson
    DaylillyLeaf StreakJefferson
    Dogwood, FloweringPhyllosticta Leaf SpotJefferson
    Dogwood, FloweringPowdery MildewTuscaloosa(2)
    Dogwood, FloweringSpot AnthracnoseTuscaloosa
    Dogwood, GrayDogwood SawflyJefferson
    Dogwood, KousaLeaf ScorchJefferson
    Elm, WingedDutch Elm DiseaseShelby
    HawthorneQuince RustJefferson
    Holly, JapaneseTwo-Lined Spittlebug DamageJefferson
    Holly, LusterleafPythium Root RotJefferson
    Holly, SavannahTwo-Lined Spittlebug DamageTuscaloosa
    HeucheraAnthracnose (Colletotrichum)Jefferson
    Hydrangea, BigleafCorynespora Leaf SpotJefferson, Shelby
    IrisIris Leaf SpotJefferson
    Ivy, EnglishAnthracnose (Colletotrichum)Jefferson(2)
    Ivy, EnglishBacterial Leaf Spot (Xanthomonas)Jefferson
    LantanaLacebugsTuscaloosa
    Maple, JapanesePhyllosticta Leaf SpotJefferson
    Maple, RedGloomy ScaleShelby
    Oak, WillowOak Spider MitesJefferson
    PeriwinklePythium Root RotTuscaloosa
    PetuniaPhytophthora BlightJefferson
    PittosporiumCottony Cushion ScaleJefferson
    Privet, JapaneseCercospora Leaf SpotTuscaloosa
    RoseBlack SpotJefferson
    RoseSpider MitesJefferson
    Spruce, Dwarf AlbertaSpider MitesJefferson
    St. AugustinegrassChinch BugsTuscaloosa
    St. AugustinegrassGray Leaf SpotJefferson
    SweetgumCercospora Leaf SpotJefferson
    ZinniaBacterial Leaf Spot (Xanthomonas)Jefferson
    ZoysiagrassLeaf RustShelby
    *Counties are not reported for greenhouse, nursery, and golf course samples.

    AUBURN ENTOMOLOGY REPORT - JULY 2005 (C. Ray)
    COUNTY CROP CATEGORY SPECIMEN NAME
    Montgomery Shrubs Ornamental Tiger Beetles
    Cleburne Gladiolus Ornamental Suspect Mites, Aphids or Thrips
    Cleburne Lantana Ornamental Lantana Lace Bug
    Tuscaloosa Oak Ornamental Oak Skeletonizer Damage
    Houston Cottonwood Ornamental Cottonwood Petiole Gall
    Houston Hickory Ornamental Ambrosia Beetle
    Houston Hickory Ornamental Round-Headed Wood Borer
    Madison Hickory Ornamental Walnut Caterpillar
    Madison Elm Ornamental Larger Elm Leaf Beetle Larvae
    Cherokee Hosta Ornamental Fungus Gnat Larvae
    Jefferson Azalea Ornamental Azalea Lace Bug Damage
    Tuscaloosa Ilex compacta Ornamental Lantana Scale
    Houston Amaryllis Bulbs Ornamental Convict Caterpillar
    Clay Camellia Ornamental Camellia Scale
    Marengo Sycamore Ornamental Blotch Leaf Miner and Sycamore Lace Bug




    UPCOMING EVENTS

    September 16-18 2005:
    Southern Christmas Tree Association Annual Meeting.
    Beavers Christmas Tree Farm
    Trafford, Alabama.
    For more information go to
    www.southernchristmastrees.org

    September 9-10, 2005:
    The Southern Plant Conference.
    Louisville, Kentucky.
    Contact: Matt Gardiner, KY Coordinator, 502-245-0238: e-mail, matthew624@aol.com; or Betsie Taylor, KNLA Exec. Dir., 350 Village Drive, Frankfort, KY 40601; 502-848-0055 or 800-735-9791, Fax 502-848-0032 e-mail knla@mis.net
    URL: http://www.knla.org
    or Danny Summers at SNA, 770-953-3311; Fax 770-953-4411; SNA Infoline, 770-953-4636; e-mail, danny@mail.sna.org;
    URL: http://www.sna.org

    September 24-30, 2005
    Alabama Farmers Federation Horticultural Tour.
    Niagra Region of Canada
    Contact Brian Hardin at 800-392-5705, ext.4217 or bhardin@alfafarmers.org

    September 30 - October 1, 2005:
    Middle Tennessee Nursery Association Horticultural Trade Show.
    McMinnville Civic Center, McMinnville, TN
    For more information contact Ann Halcomb by: phone: 931-668-7322; fax: 931-668-9601; e-mail: mtna@blomand.net,
    http://www.mtna.com/ or http://www.southeasternnursery.com/mtna/

    October 3-4, 2005:
    North Alabama Middle Tennessee Tour
    Hosted by Alabama Nursery and Landscape Association
    For more information contact Linda VanDyke at ALNLA: 334-821-5148

    October 23-26, 2005:
    IPPS Southern Region of North America 30th Annual Meeting.
    Gainesville, Florida.
    For more information click on http://www.ipps.org/SouthernNA/programs.html

    January 5-6, 2006:
    Mid-States Horticultural Expo.
    Kentucky Fairgrounds, Louisville, Kentucky.
    NOTE: Kentucky will host this new winter trade show. The event was created with cooperation from the Kentucky Nursery & Landscape Association, the Tennessee Nursery & Landscape Association, and the Southern Nursery Association. The Kentucky Fairgrounds is a 400-acre facility with more than 1 million square feet of indoor space.

    February 2-4, 2006:
    Gulf States Horticultural Expo.
    Mobile Convention Center, Mobile, Alabama.
    For more information email: info@gshe.org
    Voicemail: 334-502-7777
    Fax: 334-502-7711

    June 21-24, 2006:
    South East Greenhouse Conference.
    For more information go to www.sgcts.org.

    August 24-26, 2006:
    The Farwest Show.
    Portland, Oregon, Oregon Convention Center.
    Contact Aimee Schendel, Oregon Association of Nurserymen, 29751 SW Town Center Loop West, Wilsonville, OR 97070; 800-342-6401; 503-682-5089 x 2006; Fax, 503-682-5099; e-mail, info@farwestshow.com
    URL: http://www.farwestshow.com

    October 6-7, 2006:
    Middle Tennessee Nursery Association Horticultural Trade Show.
    McMinnville Civic Center, McMinnville, TN
    For more information contact Ann Halcomb by: phone: 931-668-7322; fax: 931-668-9601; e-mail: mtna@blomand.net,
    http://www.mtna.com/ or http://www.southeasternnursery.com/mtna/

    August 23-25, 2007:
    The Farwest Show.
    Portland, Oregon, Oregon Convention Center.
    Contact Aimee Schendel, Oregon Association of Nurserymen, 29751 SW Town Center Loop West, Wilsonville, OR 97070; 800-342-6401, 503-682-5089 x 2006; Fax, 503.682.5099; e-mail, info@farwestshow.com
    URL: http://www.farwestshow.com

    October 5-6, 2007:
    Middle Tennessee Nursery Association Horticultural Trade Show.
    McMinnville Civic Center, McMinnville, TN
    For more information contact Ann Halcomb by: phone: 931-668-7322; fax: 931-668-9601; e-mail: mtna@blomand.net,
    http://www.mtna.com/ or http://www.southeasternnursery.com/mtna/


    Send horticultural questions and comments to ktilt@acesag.auburn.edu.

    Send questions and comments to fischbr@auburn.edu.

    Letters to Bernice Fischman - 101 Funchess Hall - Auburn University, AL 36849.