April 30, 2003 | By: Aimee D. Heald
LEXINGTON, KY.

Burley growers have to take a lot into consideration when choosing a variety. The University of Kentucky College of Agriculture regularly conducts field trials on tobacco varieties and then publishes the results to help growers make decisions.

“Disease resistance, yield potential and maturity often are the most important traits a burley grower has to keep in mind,” said Bob Miller, UK agronomy professor specializing in burley variety development. “Our publication describes these traits for nearly all varieties and hybrids currently on the market.”

The 2003 Guide to Burley Tobacco Varieties, revised by UK tobacco specialists Bob Pearce, Gary Palmer and Bob Miller, is accessible via the Internet at http://www.uky.edu/Ag/Tobacco/

Miller said burley growers need to assess the current state of disease problems on farms where they will plant tobacco before selecting a variety. 

“It’s important to remember that varieties are not the only factor to consider for disease control,” he said. “Crop rotation, site selection and the use of fungicides are all important to the overall strategy.”

Each year black shank, black root rot and the virus complex cause more damage to tobacco than any other diseases. Miller said if growers have black shank or black root rot problems and do not take steps to control them, they can expect the disease-causing organisms to persist and continue to cause problems.

”Viruses included in the virus complex have become more common in many areas,” he said. “It may be important to consider selecting a resistant variety.”

Varieties detailed in the publication received a rating for the level of black shank resistance. Miller said the ratings range from zero to 10, with zero meaning no resistance and 10 meaning very high resistance. Ratings were based on numerous field trials under black shank conditions.

“At this time there are no varieties of burley tobacco which have a very high resistance to all types or races of black shank,” he said. “On average, a variety with a rating of six for both races would be expected to have fewer plants die and have less root damage under black shank conditions than a variety with a four or five rating.”

The publication also rates each variety for virus resistance. Viruses included in the “virus complex” are tobacco etch virus (TEV) and tobacco vein mottling virus (TVMV). Varieties with an “R” rating have a high level of resistance to TVMV and a medium resistance to TEV. A variety with an “S” rating has no resistance to these viruses. 

Miller said the publication rates varieties for black root rot and tobacco mosaic virus resistance. Although the publication also contains fusarium resistance ratings for varieties, they are based on one-year’s data with one strain of fusarium and ratings may change as more data are collected.

Relative yield scores were given to varieties based on disease-free conditions and scored from one to 10. Miller said that means a variety with a relative score yield of seven would be expected to produce a greater yield than a variety with a lower score if there are no diseases present.

“Of course, disease, weather, management and other factors affect the actual performance of a variety on a particular farm,” he said. 

One other area of focus in the 2003 Guide to Burley Tobacco Varieties is maturity. Miller mentioned that the length of time from transplanting to flowering is important for many growers. Each variety was assigned one of five maturity classes from “Early” to “Late.”  The Guide is available on the web athttp://www.uky.edu/Ag/Tobacco/.

Tobacco varieties will be the topic of a tour at the upcoming All Commodity Field Day to be held June 12, 2003 at UK’s Spindletop Farm in Lexington. For more information about the field day, contact your local county Extension office or field day chairman Morris Bitzer at 859-257-3975.

Contact: 

Bob Miller  859-257-4727