LSU AgCenter Provides Greenhouse Tomato Growers With New Ideas

Hanna Y. Hanna, Schultz, Bruce

Carrie Fletcher, research supervisor at the LSU AgCenter’s Red River Research Station, demonstrates pruning of suckers on a tomato plant during the station’s 10th annual Greenhouse Tomato Seminar.

LSU AgCenter researcher Dr. H.Y. Hanna demonstrates the technique of transplanting at the 10th annual Greenhouse Tomato Seminar at the AgCenter’s Red River Research Station. The annual event is designed to provide greenhouse tomato growers with practical tips and the latest research information.

News Release Distributed 03/06/06

BOSSIER CITY – LSU AgCenter experts at its Red River Research Station gave greenhouse tomato growers some new ideas to save money and boost production at a recent field day (Feb. 24).

Among those ideas, LSU AgCenter researcher Dr. H.Y. Hanna demonstrated the inverted gutter system, which is used extensively in Canadian greenhouses, that employs a series of gutters to channel runoff nutrients – keeping the greenhouse clean and dry and allowing nutrients to be recycled.

Reducing the amount of moisture on the floor of a greenhouse helps prevent disease, he explained. Adding good air circulation from overhead fans further helps prevent disease, Hanna stressed.

Before installing such a gutter system at the Red River Research Station greenhouses in 2005, "It was a miracle my crop was not wiped out with disease, especially botrytis," Hanna said.

The gutters, made of plastic-coated metal, are inverted in a configuration that allows runoff to be collected in a series of pipes.

Converting the research station greenhouses to the gutter system has increased the fall crop yield from a previous level of 8.4 pounds per plant to 9.4 pounds, since it was installed in August of 2005, he said.

"I have to do this for several years before I can tell you that you will get higher yields," Hanna advised growers, however.

Hanna also has a precision diesel-fueled heating system that uses ductwork and plastic tubing to direct warm air to the growing media. That helps to keep it at the optimum temperature of 75 degrees for the roots.

"I want the hot air to come out of the convection tube and hit the side of the media bag," he said, adding the old systems that used heaters to blow hot air over the plants are obsolete.

"Change it as soon as you can," Hanna said of such systems. "It is a waste of money."

The LSU AgCenter researcher also said the Red River Research Station has saved 36 percent with its new heating system.

Hanna said attention must be paid to the heater to make sure it is burning a clean, blue flame. A yellow flame indicates the heater isn’t burning cleanly, and that can make plants drop their flowers.

Hanna grows all tomatoes in a soilless medium instead of soil to prevent the spread of nematodes and other soil-borne pathogens.

But the researcher said care must be taken when choosing material for growing. Hanna explained that pine bark that has not been composted for at least three months is not recommended.

Perlite, the research station’s choice, is good because it is inexpensive and can be re-used if it is cleaned with a hot water pressure washer after each growing season.

On the other hand, Rock wool is too expensive for most growers, he said.

Hanna said the Red River facility has tested 20 varieties of tomatoes. Geronimo is the highest producing variety, but quality is an issue, Hanna said. "I don’t like the look of the fruit. I don’t like the color, and I don’t like the shape," he said.

The Quest variety is resistant to cracking and rough shoulder, he said, while the Trust variety tends to shrink because it loses moisture. The Clarance variety is popular in Canada, but Hanna said its drawback is small fruit.

Hanna said leaves on greenhouse tomato plants should be pruned to allow 13 to 15 mature leaves per plant – to ensure adequate sunlight to the fruit.

He also described several simple remedies for problems faced by small growers.

For example, Epsom salts can be used if a plant is suffering from magnesium deficiency, which shows up with mottled, discolored leaves on the lower part of the plant. Roughly a fifth of a pound of Epsom salts per 300 gallons of water is sufficient, he said.

Burn spots on leaves resulting from condensation dripping can be prevented by spraying the underside of the greenhouse plastic cover with a product called Sunclear, according to Hanna.

More than 40 people attended the free session. Among them was Lee Wise, a retired firefighter from Natchitoches Parish. Wise said he has fruit trees, but he wants to establish a greenhouse for growing tomatoes to make extra income.

But he said Hanna provided considerable information even for growers without greenhouses.

"Even if you’re growing in the field, you learn a lot," Wise said.

Hanna’s descriptions of diseases and their causes were helpful, he said.

"I’ve seen these diseases all my life but I didn’t know what caused them," Wise said.

Ricky and Debbie Otwell of Arcadia have a full-time greenhouse operation. They said they learned a lot from the session, even though they’ve been in the business for eight years.

"I always learn something," Debbie Otwell said. "The new gutter system is something I’m interested in."

Ricky Otwell said they got their start in greenhouses as a result of the work of the LSU AgCenter in research and educational programs for growers.

Elmore Morris of Haughton said the methods Hanna demonstrated are practical and affordable. He said he has a vegetable business that doesn’t use greenhouses, but he still learned from the session, especially from the attention spent on diseases and disorders.

Morris said he got at least one idea that he will follow up on immediately.

"I’m going to go buy some Epsom salts right away," he said. "I never thought of that."

Chris Oefinger from the Northeast Texas Community College said he attended the field day to get ideas for establishing a greenhouse program.

More information on growing tomatoes in greenhouses is available on the LSU AgCenter site.

General information on the variety of programs offered by the LSU AgCenter – on topics ranging from agriculture and natural resources to 4-H youth development to nutrition and health – can be found at or by visiting your parish LSU AgCenter Extension office.

3/14/2006 4:35:30 AM
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