Healing herbs

2017/2018 Disease Control Guide - Case Study

Ritter Greenhouse in Bridgeton, Mo., prevents and eliminates plant diseases on its container and hydroponic herbs.

October 25, 2017

Ritter Greenhouse grows basil in the summer and lettuce in the winter.
Photo courtesy of Scott Mason

Basil is known as the king of herbs for good reason. It’s the most popular herb among American consumers, with the market growing around 10 percent a year over the past decade, according to the United States Agency for International Development.

The increased demand for fresh herbs was driven by the restaurant and retail food market. In addition, plant sales are strong as home gardeners discover how easy (and delicious) it is to grow herbs.

Ritter Greenhouse in Bridgeton, Mo., has been serving the St. Louis market since the 1960s. “At our roots, we were originally a produce farm,” owner Scott Mason says. “My father-in-law started Ritter Produce and was a truck farmer on these original 8 acres. He also grew produce on a few other sites around the county. He put up hoop houses to get a jump on the crops, and eventually, that led to container plants, which he started selling as well.”

Eventually, the produce operations were overtaken by plant sales. “We started greenhousing around 1993,” Mason says. “We’ve been moving to exclusively growing greenhouse plants ever since.”

Along with the container plants grown for the retail trade, Mason added hydroponic greenhouses to provide basil and lettuce to restaurants and markets. “We saw more and more information on hydroponics pop up, and we were hoping to level out the peaks and valleys,” he says. “Now we grow basil in the summer and lettuce in the winter.” Mason is excited to note that operations were recently doubled, adding another 3,000 square feet of hydroponic greenhouses.

Ritter Greenhouse performs a preventive disease program on its basil crops.
Photo courtesy of Scott Mason

Maximizing plant health

Ritter’s head grower, Tiffany Watson, focuses on maximizing plant health and minimizing sprays, but when the need arises, she looks to OMRI Listed products first. “In our hydroponic operation, we have been very fortunate,” she says. “We’ve had very little disease pressure on our basil, although we’ve had to spray for thrips and caterpillars.”

To combat the insects, Watson turned to Triact 70 from OHP. The clarified extract of neem oil effectively controls insects and mites, but as Watson points out, “It doubles as a fungicide. It acts as a suffocant on fungal spores, so we get double duty.”

Watson also uses an arsenal of cultural practices to minimize inputs. “We have a lot of air flow in there,” she says. “We now use six-inch spacing where we used to use eight-inch spacing, so we’ve also found that proper harvesting in a timely fashion before the plants get too dense also helps. We harvest every week.”

As well as managing the hydroponic operation, Watson grows container plants. “We grow a lot of herbs,” she says. “We have a local herb society and service a lot of independent garden centers with 3- or 4-inch pots.”

Watson works closely with OHP marketing manager Andy Seckinger and has run several trials on various products. “Last year, we had issues with some of the plants getting too tall,” she recalls. “You can’t PGR them [use plant growth regulators], and then I saw that a pre-tagged order was getting yellowing and leaf drop.”

Watson discovered that there were actually two agents of destruction at work. “We found we had downy mildew as well as Alternaria. I was very worried,” she recalls. “What was I going to do? The plants were supposed to go out the following week.”

Watson agreed to trial a combination remedy that Seckinger suggested. “I sprayed with Triact 70 and the highest rate of Triathlon BA,” she says. Triathlon BA is an OMRI Listed preventive biofungicide and bactericide. She mixed a batch and crossed her fingers.

“It worked,” she reports. “It got the disease under control, and the plants put on new growth right away, and the plants looked a lot better.” She had shippable plants by the deadline.

“Now we do a preventive program. There’s not many options for fungicides on herbs,” Watson says. “If we have basil in the house and a string of cloudy weather, I spray them with Triact 70 once a week, or I will alternate with Triathlon BA. If an issue comes up, I might use them both together, or use the Triathlon BA at the maximum rate.”

Mason prides himself on running an environmentally friendly operation. “We in the hydroponic industry were just told that we can’t really be organic because we don’t grow in soil,” he explains. “But as long as we’re doing everything we can and using OMRI Listed sprays, we are being good stewards. We gladly trial the OMRI Listed products by OHP that Andy shares with us.”

“The basil is harvestable the day after we spray with Triathlon BA,” Watson says. “The re-entry is only four hours and it’s very gentle. It takes care of botrytis, too. We grow herbs very early in the spring and it takes care of that. It covers a lot of different problems. I really like it. It’s a great product.” — Helen M. Stone