In the past several years, double-crop curing of dark tobacco has grown in popularity with growers.

While demand for the crop is expected to be down in 2009, Andy Bailey, Extension dark tobacco specialist in the University of Kentucky College of Agriculture, foresees at least a portion of the crop being cured this way.

"The demand for double-crop curing will go along with production demands," he said. "If production demands rise, you'll see more double-crop curing."

Double-crop curing helps growers meet their contract requirements without the expense of building new barns. It is done by transplanting the first crop early, then transplanting a second crop five weeks later. Growers will raise two distinctively different crops. Once matured, growers aggressively fire cure the first crop in the barn and take it down in time for the second crop to cure.

"This system requires the grower to speed up the curing process," he said. "Double-crop curing is more feasible for dark-fired tobacco where the curing process can be accelerated, unlike in dark air-cured and burley."

Bailey has studied double-crop curing since 2005, and is looking at different production practices to determine which way produces the lowest levels of tobacco-specific nitrosamines, a harmful carcinogen. These practices include different ways to apply moisture to the crop following curing and prior to takedown, the effects of time delays in stripping and various takedown methods.

He is also studying which dark tobacco varieties work best in a double-crop curing situation.

A few growers have practiced double-crop curing dark tobacco on a small scale since the mid-1990s but double-crop acreage has seen its largest increases since 2006, with 2008 being the biggest dark tobacco crop since the 1970s.

In 2008, 40 percent of all dark tobacco growers used double-crop curing on at least a portion of their crop, and 20 to 25 percent of the entire crop was double-crop cured. An over-supply of dark tobacco is expected to drive down demand this year, but Bailey anticipates some of the larger growers will continue to double-crop cure.

Despite the increase in interest in double-crop curing, Bailey said it will not work in all situations.

"I don't expect to ever see more than half of the entire crop being double-crop cured," Bailey said.

Double-crop curing requires extra management on the grower's part. They must treat each crop individually, with each having its own set of insect and disease risks. Growers need to be careful about sprayer contamination between crops.