North Carolina State University is firmly dedicated to expanding stevia production with a team of researchers working on the economics of growing stevia to varietal development to weed and disease control and more.
David Shew, a professor of plant pathology at N.C. State who is instrumental in the efforts to expand stevia production across the Southeast, says this support and the collaborative four-year study are vital for developing best management practices for producing stevia and providing the answers growers need.
“We began our research work in 2011 with the goal of exposing growers to stevia as a possible alternative crop, particularly in eastern North Carolina,” Shew explains. “As we began the research we had far more questions than answers. Seven years later, there are still a lot of questions but we now have many answers in terms of weed and disease control, varietal development and other agronomic practices.”
Hal Teegarden, president and CEO of US Stevia, says a number of farmers have already reached out to the company, expressing interest in growing stevia next year. Like tobacco, stevia will be a contract crop and US Stevia is interested in contracting with growers who want to try their hand at growing stevia.
“I’ve had a number of conversations with growers and there is a quite a bit of interest in stevia,” Teegarden said.
The next big step will be the completion of the extraction and drying facility in Laurinburg. Teegarden says work has begun, but a completion time has not been set. Once the facility is completed, it is expected to be the first stevia extraction plant in the United States. Today, the lion’s share of stevia is extracted in China with facilities also in South America.
“We believe, as far as we know, that we will be the first to produce a ‘grown and made in the USA’ finished product and we feel that’s important. We have a fairly aggressive timeline to get things in place and we are working toward that. Hopefully in the not too distant future, we will begin extraction in the U.S. and move it on from there,” Teegarden says.
For growers who want to produce stevia next year, US Stevia will work with them to provide a market for their crop and will also put them in touch with greenhouses to source the stevia transplants to produce a crop. Teegarden says US Stevia will provide help and guidance for farmers willing to try their hand at growing stevia.
A big plus for stevia is that it is a good rotation crop for tobacco. Teegarden emphasizes that it grows well in areas where tobacco is grown. Another positive is a lot of the idle tobacco infrastructure and equipment can be used in stevia.
Stevia begins as a seed, is seeded into float trays, and is then grown in float bays that are used for production of tobacco transplants. Cuttings can also be used to start plants. Plants are grown for 5 to 7 weeks before transplanting to the field, similar to transplanting tobacco seedlings.
Stevia (Stevia rebaundia) is an herbaceous perennial native to Paraguay. It is a rapidly emerging specialty crop in the United States as more companies seek improved sugar substitutes. Stevia leaves contain glycosides up to 300 times sweeter than sugar that can be extracted for use as a nonnutritive sweetener. The plant has been used in other countries for many years as an all-natural, no-calories sweetener.
The United States banned stevia usage in the early 1990s, unless labeled as a dietary supplement. But in 2008 USDA approved stevia for use as a food additive. Since then, stevia products have mushroomed at retail outlets across the United States with such brands as Truvia, Zevia, Sweet Leaf and Stevia in the Raw.
Teegarden points to global market studies that show the U.S. stevia market was valued at $150 million in 2013, $578 million in 2013, $710 million in 2017 and is projected to exceed $10 billion in 20 years.
Right now, N.C. State is actively working on developing best management practices for producing stevia. The big challenges are weed control and disease control.
Alyssa Koehler, a Ph.D. graduate student in N.C. State’s Department of Entomology and Plant Pathology who has worked in stevia since 2012, is looking at fungicide programs to control diseases in stevia.
Currently there are no fungicides registered for stevia, but Koehler is optimistic that the multi-state collaborative research effort will help speed up the registration process. Koehler is working on disease management and over wintering studies in stevia and examining the efficacy of fungicides on treating diseases.
One disease that may be a problem is charcoal rot that may be weakening stevia plants in the winter. Septoria leaf spot is another disease problem. White mold caused by Sclerotinia sclerotiorum was also observed in research plots and second year production fields, but will not require applications of fungicides.
“If you have a field history of stem rot caused by Sclerotium rolfsii, you are going to want to apply a fungicide. In fields where stem rot is not problem, you won’t need to spray,” Koehler says.
However, Septoria leaf spot is likely to be the one disease that will need to be treated throughout North Carolina. “Our efficacy data shows that fungicides work extremely well in controlling this leaf spot. We hope to have a fungicide label approved soon for farmers to control leaf spot,” she says.
In fact, Koehler notes that tobacco is a good rotation crop for stevia because it doesn’t share the same diseases as stevia.
In many parts of the world stevia is grown as an annual primarily due to cheap labor where planting can be done by hand, but Shew notes that this is not the most viable model in North Carolina where stevia will likely be grown as an perennial with three of production as the goal. “Any longer than that diseases and pathogens are likely to show up,” Shew says.
Koehler adds that stevia plants are also larger in that second year with more leaves to harvest for the valuable glycosides. And Teegarden adds stretching a stevia crop over three years offers better returns and helps lower the establishment costs for growers.
Teegarden encourages farmers who are interested in learning more about growing stevia to contact US Stevia at 910-706-1556, or visit the US Stevia web page at www.us-stevia.com.
Source: John Hart, Southeast Farm Press
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