From Tobacco Wikipedia
Burley tobacco is a light air-cured Tobacco used primarily for cigarette production. In the United States it is produced in an eight state belt with approximately 70% produced in Kentucky. Tennessee produces approximately 20% with smaller amounts produced in Indiana, North Carolina, Missouri, Ohio, Virginia, Maryland and West Virginia. Burley tobacco is produced in many other countries with major production in Brazil, Malawi and Argentina.
In the U.S., burley tobacco plants are started from pelletized seeds placed in polystyrene trays floated on a bed of fertilized water in March or April. Transplanting begins in May and progresses through June with a small percentage set in July. Producers must contend with major diseases such as black shank and blue mold and insects like aphids, hornworms and budworms. Plants are topped by removing the developing flower head at approximately 60 days from transplanting and treated to prevent the growth of side shoots called suckers. Topping allows energy that would have produced a bloom to promote leaf expansion. At approximately four weeks after topping the tobacco is stalk cut using a knife that is shaped like a tomahawk. Each plant is speared, spiked or spudded (the terminology depending on the geographic location) onto a stick topped by a metal spear, spike or spud that fits over the stick. Each stick will contain five or six stalks. Sticks of green cut tobacco are most often allowed to field wilt for three or four days prior to hanging in a barn. Tobacco is allowed to air cure for eight or more weeks turning from the normal pale green to yellow and then to brown. Burley that cures too quickly will retain some of the yellow pigments as well as chemicals that normally break down with a slower cure. The quality achieved by U.S. burley producers is primarily due to natural curing conditions. Once fully cured burley is taken down, sticks are removed and leaves are stripped from the plant into grades by stalk position. Leaves are baled by grade and taken to a receiving station run by a tobacco manufacturer or leaf dealer.