Mark J. Arena,
Agent, Clemson Extension Service

Recent work with RootShield, a biological fungicide, has provided experience that should prove valuable to greenhouse managers and nurserymen. The work grew out of a collaboration between Clemson Extension Service and Baucom's Nursery in Summerville, S.C. Hands-on observations were later confirmed by formal experiments.

RootShield (Trichoderma harzianum strain T-22) came to the attention of Clemson Extension Agent Mark J. Arena at the 1998 Ohio Florists' Association shortcourse. Based on the presentations of the manufacturer, BioWorks, Inc., along with scientific evidence and testimonials from growers, he decided to try it at Baucom's.

Baucom's of South Carolina opened for business in February 1997 with 176,000 square feet of heated space and four acres of outside production area. In the fall of 1997, two acres were added for plug production. Since then, expansion has included two additional acres of greenhouses and eight more acres of field beds. Immediate plans call for a new production facility as well as one acre of cold frames. The company also owns and operates nurseries in Charlotte, N.C., and Mt. Dora, Fla. When the collaboration began, Baucom's was using a preventative fungicide program in which chemicals were the only products used.

In August 1998, we began trialing RootShield at Baucom's Nursery in Summerville, S.C. RootShield is labeled for control of Pythium, Rhizoctonia, and Fusarium. It works by colonizing the roots of a plant and then killing off other pathogens that attack those roots. It is important to stress that this is a preventative action; existing disease cannot be cured. It is marketed in both drench and granular formulations. A drench application was used in our work.

The first experiment was conducted on fall pansies. Pansies are susceptible to the three pathogens for which RootShield is labeled; Thielaviopsis can be an additional problem in the heat of summer. Pansy plugs were brought in and transplanted into 606 flats, then transferred to the greenhouse to root out before being placed outdoors. The day after transplanting, several varieties were treated with RootShield drench at the recommended rate and marked. All other plugs were treated with Banrot 40 WP at the recommended rate. Ten days later, all plugs were moved outdoors and grown under a shadecloth. We continued this trial for the entire fall pansy production schedule. The only difference between treatments was that the plants treated with Banrot received an additional drench of Subdue plus Cleary's 3336 four weeks later. Plants treated with RootShield received only the single treatment at the plug stage. The plants' roots were evaluated when they were scheduled to be shipped. In all cases, plants treated with RootShield produced either comparable or better quality roots than those treated with the chemical fungicides.

We continued to trial the product on several different plants throughout the fall with great success. With poinsettia production ahead, we set up a traditional, "pure research" experiment, using controls, replications, and experimental design. Pythium is probably the major pathogen of poinsettia roots. Vegetative cuttings of 'Spotlight Dark Red' were used for this experiment. At root initiation, four treatments were used, with twenty replications:
Treatment 1: no chemicals applied
Treatment 2: one application of Banrot
Treatment 3: one application of Banrot followed by monthly drenches of Subdue plus Cleary's 3336
Treatment 4: one application of RootShield
All treatments were made at the recommended label rates. All of these plants were maintained under Baucom's standard poinsettia production program. During the third week of September, water collectors were placed under the plants to prevent them from drying out. While standard practice in many nurseries, water collectors can create additional disease pressure. These collectors held approximately 3/8" of water after the overhead boom had watered the plants. On average, the water remained in the collectors for about four hours. On 1 December 1999, all plants were evaluated for root development and growth.

Once again, the results of the experiment reflected the effectiveness of RootShield. Treatment 4 (one drench of RootShield) produced the best root system and was superior to all other treatments. Root quality and quantity were excellent. Roots had great branching, excellent color, and good root hair development.

In addition to this research, RootShield was tested on several other poinsettia varieties, with various pot sizes. RootShield performed as well as and on certain varieties far better than the preventative chemical fungicides. In fact, the Florida facility treated all its poinsettias-over 250,000 plants-with RootShield and did not lose a single plant to root-related problems. Due to all the positive results and benefits RootShield offers, Baucom's has now begun treating all its plugs with RootShield. In fact, Mr. Gary Baucom and his staff have switched to an almost completely biological fungicide program. Several other nurseries in the coastal Carolina area are also reporting positive results with RootShield.

RootShield offers us some comfort in knowing that it is actively seeking out and protecting the root system from other fungi. But RootShield will not protect a plant from improper growing practices. The grower must continue to be attentive to cultural practices, including maintaining a good fertilizer program and adjusting for the right pH. There is always a chance that we may produce an environment favorable to disease. For example, we continually scout for and correct situations such as growing plants in a low spot of the floor, which produces a puddle and opens the roots to damaging pathogens. In addition, we monitor for root quality constantly. Some minor adjustments had to be made on equipment to prevent damage to injectors; the decanting process recommended on the label seems to have solved this.

Overall, RootShield has been an asset to the operation on several levels. First, the drench application has reduced the overall cost of Baucom's fungicide program by almost 60%. Second, employee safety: RootShield provides a shorter reentry interval (soon to be zero) and eliminates the risk of exposure to hazardous chemicals. Finally, using a biological fungicide rather than chemical fungicides reduces environmental concerns.

In closing, I would like to offer some advice to readers who may wish to try RootShield. Some of the more important facts to remember are:
1) Use the product correctly. RootShield is only preventative, not curative. This means roots must be healthy and disease free at the time of application. Carefully inspect for existing disease.
2) Time and type of application. Determine when and what type of application is going to be most effective for your situation. With RootShield, the earlier it is applied, the better. Every day that the roots are not protected just increases the chances for root problems.
3) Proper storage. Do not store RootShield in your chemical storage area. RootShield contains living organisms, which will be killed by the fumes from chemicals stored nearby. Very high temperatures will kill the organisms. For best results, refrigerate the product until you are ready to use it; if that is not possible, at least store it in a cool, shady place.
4) Education. The user needs to clearly understand how this product functions and/or operates. This also means understanding the equipment that will be used for its application.
5) Second Application. It is recommended that you make a second application of RootShield at half strength ninety days after the initial treatment.

If growers follow these guidelines and label directions, I am sure they will benefit as much from this product as we have. If any questions arise, don't hesitate to call BioWorks (315-781-1703) or visit their web site at (http://www.bioworksbiocontrol.com). Good luck, and here's to healthy roots!

Clemson Extension Service would like to express its thanks to both Baucom's Nursery and BioWorks for their support on this project.

Natural Defense with Biofungicides

Christopher Hayes, Ph.D.
Director of R&D and Marketing, BioWorks, Inc.

Biological fungicides, or biofungicides, are living, "breathing" microbes that naturally keep disease-causing pathogens from damaging and ultimately destroying plants. Following their application to the plant, a select few biofungicides have the ability to grow on or near the root, stem or foliar surface. The ability of a biofungicide to grow on a range of plants in a diversity of growing mixes and protect against various pathogens is essential for commercial success.

EPA-registered biofungicides are subjected to and evaluated by the same criteria used to register chemical fungicides. Fungal and bacterial based biofungicide products are tested for effectiveness and potential interactions with human health and the environment. Effectiveness is unproven while toxicity and health and environmental effects are not known for the unregistered "snake oil" products currently on the market. Growers are assuming a big risk, to their workers and their plants, when using unregistered products to control diseases.

Typically, biofungicides prevent diseases from damaging plants and therefore should be applied before diseases invade plant tissues. Under low to moderate pathogen attack, biofungicides will successfully defend the plant. If a disease has already infected the plant tissue, use a chemical fungicide first to "clean-up" the plant and eradicate the disease, then apply a biofungicide to prevent diseases from entering.

Mechanisms of Biofungicides:
Colonizing, or growing on, the root, stem or leaf surface helps block a pathogen's entry site into the plant. The EPA-registered biofungicide, Trichoderma harzianum strain T-22 (the active ingredient found in RootShieldÒ) is a fungus that establishes itself on the outside of the root system in the rhizosphere, or root zone. RootShield grows along the entire length of the root system establishing "squatter's rights" while forming a protective barrier against pathogen attack. One application of RootShield can provide disease protection for up to three months. (Insert Grower Pic 4 of cover) Monte Flack, grower of Mid-American Growers (Granville, IL) stated, "One of my New Year's resolutions was to provide all major crops with RootShield. I want my roots to work with me, not against me. This year's Easter lily crop was RootShield protected and the roots were fabulous and numerous with an unbelievable bud count. I can't wait 'til poinsettias; bring on the RootShield." And Pamela and Frank Arnosky, organic growers and owners of Texas Specialty Cut Flowers (Wilberley, TX), mentioned RootShield in their monthly column, Growing for Market, "We were glad to have an alternative on poinsettia and so we used RootShield on our crop this year and it looks great. In fact, it's the nicest crop in a long time. The roots are very strong and the tops are nice and green."

Some biofungicides release compounds that can have a detrimental effect on pathogens. However, some of these biofungicides produce antibiotics that, while reducing the growth of selected pathogens, can also result in pathogen resistance developing quickly. The active ingredient in RootShield releases enzymes that dissolve pathogens like Fusarium, Rhizoctonia, Pythium and other diseases, effectively "eating" the disease (Insert picture of hyphae with holes). Growers have reported good success with RootShield in controlling diseases. Sharon Alley, Production Manager of Alexander Plant Farm (Alleyton, TX) states, "We were always looking for a better way to control any type of root problems, such as Pythium, Rhizoctonia, etc., especially in the spring. We were having to treat with several different fungicide drenches almost on a weekly basis. We were introduced to RootShield, took it with a grain of salt, but decided to try it. It didn't take long to figure out that RootShield really worked at controlling root diseases, and saved us hours of costly and time consuming drenching. For the last two years we have had little to no problems when using RootShield." In fact, stopping these root-nibbling diseases like Pythium and Rhizoctonia allow feeder roots to fully develop, potentially increasing nutrient and moisture uptake.

Since most biofungicides are preventative, it is important to use them early in production. They can be successfully used at any time during production given they are applied to pathogen-free plants. If a disease problem potentially exists, it should be cleaned up followed by a biofungicide to extend protection of the plant. However, check to make sure the biofungicide is compatible with the chemical used. RootShield is compatible with most commonly used chemical fungicides. Some growers choose to apply a chemical fungicide to a growing media containing RootShield Granules, or they follow up the chemical application with an application of RootShield Drench. Both products will protect the new plant roots against pathogen attack. In this way, additional chemical applications can be reduced or eliminated. (Insert Grower Pic 1 of cover)According to Bill Turner, General Manager of Van de Wetering Greenhouse (Jamesport, NY), by using RootShield in his operation he has been able to reduce his overall chemical fungicide program. And Martin E. Stockton, Head Grower of First Step Greenhouses (CA) stated that "RootShield has eliminated the need for preventative fungicide treatments on our key crops. This has dramatically reduced labor and chemical expenditures. Culturally, we have experienced a healthier, larger root mass, which seems to be less vulnerable to cultural errors such as over-watering. We believe we are supplying our customers with the added value of a RootShield treated plug where the fungi will continue to protect the roots. RootShield has added a sense of pride to our company in knowing we are using an environmentally responsible product."

Typically, biofungicides work best in environments where they are isolated, but this can limit their broad scale use in the greenhouse industry. However, RootShield, a hybrid strain developed at Cornell University over 17 years ago, has been shown to colonize the roots of plants grown in all types of growing media, e.g. peat, bark, rockwool, etc., under wide pH and temperature ranges. RootShield can be mixed, top-dressed, or used through an irrigation system, including Ebb & Flood. (Insert Grower Picture)Kevin McGuckin, owner of Indian Creek Nursery (Brenham, TX) stated, "When I changed all my benches to ebb & flood, I experienced problems with Pythium 5 to 6 weeks after drenching. With RootShield added to the initial drench, I have no problems even with my 12 week crop".

Biofungicides can be successfully used to prevent pathogens from attacking a plant. Optimal defense depends upon the biofungicide being able to either out compete the pathogen, attack it, or both. RootShield has the ability to grow on the roots, attacking and out competing the pathogen. If the pathogen tries to cross the "shield" formed by RootShield, it will be eaten. RootShield is EPA-registered, has a zero hour REI (restricted entry interval), and is organically listed (OMRI Listed). The product is available as a granule (RootShield Granule) for addition to a growing media or as a top-dress. This summer the wettable powder, RootShield DrenchÒ, will be renamed PlantShieldÒ, a wettable powder for soil drenching or foliar application. Foliar applications of PlantShield will prevent Botrytis and suppress mildews. RootShield Granules and PlantShield Wettable Powder are the most widely used biofungicides in the greenhouse industry and transplant market today. They offer a user-friendly approach to natural disease control that has proven itself with growers around the country. While RootShield is not a "magic bullet", it is an effective tool in controlling numerous types of fungal plant pathogens on a broad range of plant types under various growing conditions.

Seedway Accelerates Commitment To Organic Growers

Leading Northeast Vegetable Seed Supplier Expands Untreated Seed Offering

Bruce E. Ulmer, C.C.A.,
Seedway Director Sales Support Services

Seedway's effort to service the organic agriculture community is nothing new. We have made untreated seed available for many years, but with the recent explosion of interest in organically produced products, we made an extraordinary effort for the 2000 growing season. Our goal was to provide organic growers an extensive offering of top-notch, high performance vegetable seed, packaged completely untreated. To achieve our goal we have published an Organic Grower Vegetable Seed Catalog, which highlights over 200 varieties in many crops, all backed with the knowledge and experience of Seedway's nearly 40 years in the vegetable seed business

Increased Organic Presence:
Recognizing the need to service our customers who produce crops organically, we continue to offer products such as seed corn, soybeans, small grains, grasses and vegetables untreated. Our line up of untreated vegetable seed was expanded this year and now includes, among other crops, broccoli, cabbage, carrots, cauliflower, cucumbers, gourds, herbs, onions, melons, peppers, pumpkins and squash along with the very popular, peas, beans and sweet corn.

At Seedway, we recognize and appreciate the efforts being made by those in the organic community to protect our environment and produce high-quality, healthy food. We are committed to offering organic growers an extensive selection of top-quality, untreated seed in many crops and varieties. Seedway has taken steps to be directly involved with providing seed and service to organic growers. Our goal at Seedway has always been to be a complete seed company, offering a wide range of seed products to growers of all types. Meeting the very diverse needs of growers continues to be our primary objective, and suppling organic producers is a key part of that plan.

The varieties selected and presented in the Seedway 2000 Organic Grower Vegetable Seed Catalog include some of the latest introductions with outstanding yield, disease resistance and appearance.

Special Products:
Of particular interest to the organic producers is a product marketed by Seedway, T-22 biological fungicide. T-22 was developed by Cornell University to fight soil-borne crop diseases using all natural, biological means and is registered with the EPA. The active ingredient in T-22 is the highly effective, beneficial fungus Trichoderma harzianum, a special hybrid strain developed by the Cornell University microbial breeding program. T-22 is different from traditional planter box fungicides that protect the seeds. T-22 protects the roots of plants. It provides natural, season-long control of diseases because it grows on the root system for the life of the plant. It is non-toxic to humans and animals, and water contamination is not a concern. T-22 protects roots from diseases caused by Pythium, Rhizoctonia and Fusarium and permits stronger, healthier root systems. In addition, it allows for great soil exploration by the root system and therefore enhances nutrient uptake and improves tolerance to stressful growing conditions. Season-long protection is achieved with one application. T-22 is approved for us on almost all crops.

Another innovative product available from Seedway is Tagetes Polynema, a marigold hybrid providing many soil and crop benefits. This product controls root lesion nematodes on high-value crops such as onions, carrots, potatoes, strawberries, watermelons, tomatoes, eggplants and more. The vigorous root growth of Tagetes Polynema reduces the number of nematodes in the root zone for the following crop. When planted and plowed down, the large top growth provides added nitrogen and organic matter to the soil. Tagetes Polynema should be planted in late spring and allowed to grow for approximately 100 days. Then chop and plow down after several days of drying.

About Seedway:
Founded in 1963, Seedway began as a field and vegetable seed distributor in Hall, NY, servicing New York and the New England states. Seedway developed it's own brand of seed corn and offered a varied product line including alfalfa, forage grasses, small grains and many vegetable crops. A great deal of our success can be attributed to the three main componets of our business; our people, our products and our service.

In 1987, Seedway was purchased by Agway, Inc. of Syracuse, NY and became a self-managed subsidiary of the Northeast cooperative. In 1993, Seedway assumed management of all Agway vegetable seed business, which has been in operation since 1934.. Since that time, the company's vegetable seed business has experienced unprecedented growth and Seedway's market area has expanded to include all states east of the Rocky Mountains and Ontario, Canada. Our office and warehouse locations include Hall, NY, Shoreham, VT, Palmetto, FL and five locations in PA.

For more information on Seedway, our untreated seed products or to obtain a free copy of the 2000 Organic Grower Vegetable Seed Catalog, contact Mead Murphy, Shoreham, VT at (802) 897-2281 or Seedway, Hall, NY at (800) 836-3710.