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Jim's Corner • Product Profile • What's Up? • Plant Profile • Upcoming Events

Jim’s Corner

Heads-up from the University (Drs. Mike Evans, Gerald Klingaman and Jim Robbins): Here we go again. With heating costs rising, greenhouse growers are considering ways to tighten up houses and exploring alternatives to traditional greenhouse heaters. One place growers have looked is to use non-vented poultry house heaters. Dr. Klingaman wrote an outstanding article on this topic back in the spring of 2001 for the AGIA bulletin (Plant Arkansas Bulletin). This story has a simple ending. You are playing a dangerous game of Russian roulette if you decide to use direct-fired heaters that are not designed for greenhouse use. Depending on the type of winter we have and the "tightness" of your greenhouse, you may cause problems for your greenhouse crops and employees.

The problem usually occurs in January and February when temperatures are the coldest and we have lots of overcast days. Under these conditions, ventilation is minimal so the toxic gases (ethylene, carbon monoxide, sulfur dioxide and more) accumulate to dangerous levels. The typical symptoms (e.g,. cupping of leaves, twisting of stems, terminal bud damage) of ethylene exposure may not occur. Instead, we pass immediately to more severe symptoms of foliar burn and a complete cessation of plant growth. Most seed and cutting propagated bedding plants are susceptible to in-house pollution and may not recover from damage for several months after exposure.

While an agricultural engineer would suggest that the greenhouse be set up for one air exchange per minute for every square foot of greenhouse space, that would seem to defeat our purpose of bringing cold outside air in if our goal is to reduce energy inputs. In summarizing, if you want to reduce your heating costs in the winter, you are playing a dangerous game if you choose to switch to direct-fired heaters, especially if the unit is not vented to the outside. Drs. Evans, Klingaman and I recommend you stick with properly vented greenhouse heaters designed with a heat exchanger. If you already have direct-fired heaters, consult your supplier or one of us for advice on venting during the cold days of winter.

Plant Board Update: Minor change, however, starting in 2003 you will NOT need a Vegetable Grower license IF you are growing vegetable plants in soil-less media. You can thank David Blackburn and Clay Parks (Parks Brothers Farms) for this. (Have you ever heard of  regulations being removed?) This regulation was kind of a throwback to an earlier time when vegetable transplants were grown in flats containing field soil. Today, the greenhouse industry almost exclusively uses soil-less artificial media.

Congratulations to Stan and Sheri McDaniel of Healthy Lawns and Shrubs in Little Rock for celebrating 25 years of being in business. Also, congratulations to Chris Olsen of Horticare in Little Rock for having his own holiday TV show highlighting his exceptional design talents. On a sadder note, we need to acknowledge the passing of an industry leader in our state, David Pittman. While most of us knew David through his nursery, Pittman Nursery in Magnolia, he is also remembered for his many years of service to the nursery industry through trade associations and the Plant Board.

It looks as if we survived another busy January and February filled with outstanding trade show conferences including the Arkansas Turfgrass Association (ATA) and Arkansas Green Industry Association (AGIA). For those that did not attend the AGIA meeting in Hot Springs, you missed some exceptional speakers. Thanks to the generosity of several businesses (Olympic Horticultural Products and SePro), the seminars offered nationally recognized names such as Dr. Ann Chase (plant pathologist) and Dr. Richard Lindquist (entomologist).

Product Profile

While traveling in California over the holiday, I noticed a snake-like erosion control barrier being used everywhere. When I got back, one of my goals was to find out more about the product. Luck was on my side. While attending the ATA trade show (see the value in attending trade shows!), I noticed that Darragh Company (Little Rock office: 1-800-489-2112) had just added this to its product line. Called SedimentSTOP™, the lightweight, biodegradable blanket comes in a 6.5' wide by 50' long roll just like landscape fabric. Once on the jobsite, you simply roll it like a jelly roll into a 50' long sediment barrier and then stake it (see photograph). Their literature indicates it is made from weed-free straw and coconut fiber. The outer netting is some kind of biodegradable organic material. For those doing construction or landscaping, you might want to give this a "looksee."

What’s Up?

Interesting websites!

The Perennial Plant Association has publicly promoted its 2003 Perennial Plant of the Year, Leucanthemum Becky™. Also, their 21st Perennial Plant Symposium Perennial Plant Symposium will be in Sacramento and San Francisco, California, July 27 - August 3, 2003.

The February 2003 issue of GMPro had an outstanding article titled "E-pest management". The article gave extensive lists of websites related to topic areas such as disease information, diagnostic sites, commercial and government sites and biological controls. Some that caught my eye include:

• Photo gallery of insects and mites on ornamental plants:  
• Descriptions of many ornamental diseases
• Plant disease fact sheets
• A massive database of commercial suppliers of biological controls

No need to worry if you missed your issue of Grounds Maintenance magazine. Now you can view and print current and past articles.

For container growers (abstract based on a research article by Stuart Warren and Ted Bilderback at North Carolina State University):

Irrigation timing had a significant effect on plant growth, container temperature and water utilization efficiency. Plants that were irrigated 1200, 1500, and 1800 HR (noon, 3 and 6 pm) significantly outperformed plants irrigated during early morning hours. Decreases in plant growth appear to be related to increase in diurnal water stress over the course of the growing season. Growers should avoid letting the container substrate dry out by late afternoon. Our data suggests that growers may want to investigate irrigating at times other than early morning.

Plant Profile

Abeliophyllum distichum Nak.
Korean abelialeaf or white forsythia
Jon T. Lindstrom
Department of Horticulture, University of Arkansas,
Fayetteville, AR 72701, tranell@uark.edu   

One of the suggestions made by students in my woody landscape plants class was to show in my lecture pictures of the plants in actual use. This is an excellent idea and I am now in quest of unusual shrubs in landscape situations. Once I find them I can include them in the list of plants to be covered in the class. As a contrast to the commonly seen forsythia, my hunt for an Abeliophyllum is on. I have never seen A. distichum used in a residential landscape – this despite all the good things I read about this plant in catalogue descriptions. Someone must be buying this plant, but where are they all getting planted?

In Fayetteville, they might exist, but in complete anonymity. Here the flower buds, produced the previous season, normally swell to open in early March only to be cruelly destroyed by a late freeze. These are the buds that actually make it through the winter. Several years now, the plant in Fayetteville has flowered lightly in the fall, especially so when the fall was long and warm. Finally this year, it looks like the plant at the University of Arkansas will flower in a noticeable fashion. I look forward to the sweetly fragrant, bright white flowers, similar in shape to a forsythia flower but smaller in size.

The form of this shrub is broad and spreading but unkempt. Final height is usually between 4-6' high. To impress a bit of order on the plant, pruning should be accomplished immediately after flowering. The passing of the flowers on Abeliophyllum allows the shrub to fade into 350 days of obscurity. It is best placed in full sun in a shrub border where other plants can continue the floral parade that started with the white forsythia.

To fill the great demand created for Abeliophyllum by the writing of this profile, take softwood cuttings in early summer. After treatment with 1,000 ppm K-IBA, cuttings root easily under intermittent mist. Usually these cuttings, once rooted, grow quickly and flower the following year.

Upcoming Events

April 18-19: Spring Meeting of the Ozark Chapter of the American Rhododendron Society, Tulsa, Oklahoma. Meeting ends with tour of Lendonwood Gardens in Grove, Oklahoma. Contact Sandra Hughes (870-793-3144).

April 28: 5th Annual UofA Golf and Sports Turf Classic, Stonebridge Meadows Golf Course, Fayetteville. Contact Marilyn at 479-575-3793.

May 6: U o fA Southwest Research and Extension Center Field Day, Hope. Contact Mike Phillips at 870-777-9702.

May 6: Tree Health Care: Managing Trees to Minimize Pests (Dr. Jim McGraw and Dr. Kim Koder), U of A Cooperative Extension Service Building, Little Rock. Contact Connie at tfshead@aol.com .

June 25: U of A Fruit Substation Field Day, Clarksville, 8:30 am to 3 pm.

August 6: U of A Turf Field Day, Fayetteville.

No endorsement is implied or discrimination intended for firms or references included or excluded from this list.

By: Jim Robbins, Extension Specialist - Ornamental Horticulture

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