January 1998

HAPPY NEW YEAR!

I hope our good fortune continues in the Nursery industry for the coming year. Things slow down a little over Christmas but it doesn't take long for winter trade shows and educational programs to get into full swing. Georgia, Tennessee and Alabama are all involved in the month of January. Of course, we think Alabama is special and would like to see you in Mobile the last weekend in January. If not, I hope you will get out to one of the shows to see what is new in the industry.

This is the month for the launching of our Nursery/Landscape Web Page at Auburn. It will always be a work in progress and hopefully offer a continuous stream of new information and links to help you in your business. If you still want your newsletter sent by e-mail, just reply to let us know. I know that for some people it is quicker to check your e-mail than to get into your browser. Bernice Fischman becomes an official Web Mistress at the launching this month. She has worked hard to get the contributing faculty to get things turned in to her so we could go on-line. We thank her for lending her artistry to our Horticulture information.

With our shrinking (nose-diving) budget, (no comments against our reigning governor) this educational/communications tool is the last avenue we have available to us to stay in contact with you on a regular basis. Enjoy your browsing and let us hear from you if you get the urge. Have a good month and come to see us at our booth at the Trade Show. We are always happy to talk plants or help you any way we can at Auburn.

THE FOLLOWING ARTICLES ARE FEATURED IN THIS MONTH'S SOMETHING TO GROW ON:

1. Effects of Surflan concentrations in irrigation water on Gardenia jasminoides radicans and Pennisetum rupeli.

2. Response of shade trees grown in in-ground containers to three container substrates.

3. Effect of split fertilizer application and irrigation on nitrogen concentration in a container growing area soil.

4. Preference of two-lined spittlebug for Ilex species, hybrids and cultivars.

5. A bud-boring cutworm: an unusual pest of native rhododendrons.

6. Review of Michael A. Dirr's Photo-Library of Woody Landscape Plants

UPCOMING EVENTS WILL BE LISTED AFTER THE LAST ARTICLE.

EFFECTS OF SURFLAN CONCENTRATIONS IN IRRIGATION WATER ON GARDENIA JASMINOIDES RADICANS AND PENNISETUM RUPELLI

As growers become more and more concerned about herbicide residues in containment ponds of recycled water it is essential to understand which herbicides are hazardous to sensitive plants. In this study dwarf gardenia (tolerant) and fountain grass (sensitive) were irrigated with water containing 10, 100 or 1,000 ppm Oryzalin, an active ingredient in Surflan and Rout. Investigators wanted to ascertain what effect these concentrations of chemicals would have on growth and other physiological functions.

They found that Oryzalin concentrations similar to those found in nursery runoff water did not reduce growth. It appears to be safe to use in a container plant production business. If, however, the concentration remains high for a long period of time, the growth of sensitive species may be reduced.

(This study was conducted by Rajgopal Bhandary, Ted Whitwell, Jeanne Briggs and R. Thomas Fernandez of the Department of Horticulture, Clemson University)

RESPONSE OF SHADE TREES GROWN IN IN-GROUND CONTAINERS TO THREE CONTAINER SUBSTRATES

This study compared growth of young trees in containers with three different soil treatments. Ash and birch seedlings were grown during 1991 and 1992 in 38 liter plastic in-ground containers substrate with the following ratios of sphagnum peat and ground pine bark: 10:30:60; 50:30:20; and 100:0:0. Trees showed better top dry weight, trunk diameter and root dry weight when grown in containers with the least soil content (10%) than in the 100%.

Production of large trees in in-ground containers leads to larger trees. The trees grow faster in the containers because it is easier to irrigate and manage fertilization. These trees thrive in a substrate with less soil as there is better drainage with the other organic media. Lower bulk density is also a positive and beneficial factor. Trees grown in this manner will survive better when transplanted into the landscape due to increased top and root growth in response to a medium with better drainage.

(Christine L. Murray, Glen P. Lumis and Calvin Chong, Department of Horticultural Science, University of Guelph, Canada).

EFFECT OF SPLIT FERTILIZER APPLICATION AND IRRIGATION ON NITROGEN CONCENTRATION IN A CONTAINER GROWING AREA SOIL

This study was conducted to determine the amount of nitrogen loading that occurs in the soil below fertilized container crops. Since it is considered detrimental to the groundwater quality when substantial amounts of nitrogen are released into the water, scientists are attempting to determine the best delivery system for fertilizers. Controlled-release fertilizers (CRF's) were considered more environmentally sound than soluble fertilizers and splitting the application seemed to be an even more sensible approach but the research has not found that to be true. Researchers found that frequent fertilization followed by large volumes of water in containers may cause the nitrogen to leach even deeper into the soil.

It is suggested that growers need to be more careful to avoid excessive fertilization, even if the method they use appears to be more environmentally sound. Growers using containers on gravel or porous fabric-covered areas must be more careful. Nurseries that use plastic covered areas and direct water to holding ponds need not be concerned.

(Study done by David J. Colangelo and Mark H. Brand, Department of Plant Science, University of Connecticut).

PREFERENCE OF TWO-LINED SPITTLEBUG FOR ILEX SPECIES, HYBRIDS AND CULTIVARS

A very sensible way to approach the problem of insecticide application in the nursery and landscape setting is to try and use plants that are naturally pest resistant. This study was conducted to determine which cultivars are the most pest-resistant so that they may be more readily available in nurseries for landscape use.

The pest used in this study was the adult two-lined spittlebug. Cultivars in the study were 137 Holly selections ranging from highly susceptible to completely resistant. Ilex cassine and Ilex opaca were highly susceptible to damage while Ilex cornuta, I. glabra, I. verticillata, and I. vomitoria were generally resistant to damage. With this information nurserymen will be better able to select pest-resistant plants and then minimize the amount of insecticides that need to be used.

A BUD-BORING CUTWORM: AN UNUSUAL PEST OF NATIVE RHODODENDRONS

The cultivation of native rhododendrons has uncovered a destructive pest that bores into and damages flower buds. The most affected cultivars are Rhododendron canescens, R. austrinum and R. alabamensis. The noctornal pest responsible for considerable damage to these popular species is the variegated cutworm (Peridroma saucia). In the past the cutworm was recognized as a pest that would damage vegetable, forage and field crops.

In January of 1994 damage to flower buds was noticed. The bud is not usually consumed totally but there is significant enough damage to destroy all bloom potential. Cutworms have only been collected in early morning or during the night, rarely in the daylight so the vast majority of the damage they do is at night. The larvae rest during the day and climb up the plant to inflict their damage at night.

The full grown larvae (light to dark brown to dark gray) of the variegated cutworm is approximately 1 3/4 inches long and has light markings along its back. The variegated cutworm is a serious problem for those atttempting to grow Native Azaleas.

(From an article published in Highlights of Agricultural Research, Winter 1997).

REVIEW OF MICHAEL A. DIRR'S PHOTO-LIBRARY OF WOODY LANDSCAPE PLANTS
BY KEN TILT

There are many "Picture Books" in the world of gardening but how many can you visit and see plant cultivars? All red maples are not the same for the conscientious gardener or landscape designer. I have bounced around Michael A. Dirr's new Photo-Library of Woody Landscape Plants on CD-ROM. WOW! There is nothing like it available. Horticopia has good information on plants and is a good program for selection and viewing of plants but it deals mostly with species. Just like in his book, Manual of Woody Landscape Plants, it is the only source that deals extensively with cultivars available in our nursery industry. Of course, you will have to buy his book as a companion resource to get plant descriptions because there is no text on the CD's, just pictures. However, the 7,600 woody plant images on the CD's are beautiful. Of course, like all slides and photos you see at plant presentations, you are usually getting the best of the specimens. When you see a nandina or chokeberry displayed on the CD, you are seeing what could be. Everyone has seen how rough a nandina can look in landscape if conditions are not right.

There are 4 CD's that contain all the pictures. I have taken it around the state with my laptop computer to demonstrate to Master Gardeners as part of my Design, Care and Maintenance class. Everyone has enjoyed the ease of use and vast array of plants available. The multiple CD format is the only thing I could find to complain about. If you were going to do a program with the CD's you would have to constantly be changing the CD's as you discussed new plants. You would certainly need to do the program in alphabetical order. Of course, most people will not be using it as a formal presentation tool.

If you have an interest in woody plants, this photo-library is a must. If you are a commercial landscape designer or nursery producer, it will or should become an abused resource just like his book has become over the years. I am on my third or fourth copy of his book and the pages are starting to fall out from my frequent use and rough handling. I hope CD's are more durable. You can get more information concerning the Photo-Library of Woody Landscape Plants by going to the Plant America web page at www.plantamerica.com or by calling 516-674-4238. The photo library is also available in Timber Press's Fall Edition 1997 catalog (800-327-5680 or www.timber-press.com) and American Nurseryman's Fall-Winter 1997-98 catalog (800-621-5727), at a cost of $149.95. The price sounds stout at first glance but have you priced coffee table books with a small fraction of the pictures? It is a bargain! The Alabama Nurserymen's Association is or will be carrying the CD's for their members. Call Linda Van Dyke at 334-821-5148 or visit the web site at www.anla.org.

UPCOMING EVENTS: