Mechanical cultivation and hand hoeing are used for weed management. The additional labor costs for hoeing are justified by the high value of the crop. Deep cultivation is allowable shortly after transplanting, but may damage crop roots if continued into the season. Cultivation and hoeing have the additional value of breaking the soil crust, allowing proper air exchange and improving crop yield and quality. For further informa- tion on weed control strategies and options, please ask for ATTRA’s Principles of Sus- tainable Weed Management for Croplands.
Adult tomato hornworm. Courtesy of Jim Occi, BugPics, www.Bugwood.org.
Topping and Suckering: When the tobacco crop is about half-grown, flower buds begin to appear. These flower heads are removed or “topped” to prevent seed formation, forcing the plant to focus on leaf production. The result is larger, thicker, darker leaves that mature more uniformly and contain more nicotine. Topping may be done by hand or with special machines that cut the flower heads and sacrifice a few leaves. Topping requires two or three trips over the field to catch all the plants.
Topping of plants also stimulates the growth of secondary stems from the base and/ or leaf axils. These “suckers” must also be removed to assure uniformity and quality. While chemicals are available to suppress suckering, these may not be allow- able under organic certification standards. The alternative is removal by hand every seven to ten days. Suckering is one of the most labor-intensive activities in tobacco production, as many plants sucker two or three times before harvest.
Tobacco hornworm larva. Photo courtesy of www.ipmimages.org.
Insect Pests and Diseases in the Field: Tobacco has a number of insect pests. Among the most threatening of these are two species of hornworm: the tomato horn- worm (Manduca quinquemaculata) and the tobacco hornworm (Protoparce sexta). Hornworm caterpillars are large and easily recognized. Considerable control can be achieved by hand picking in conjunction with other labor-intensive field operations. Post-harvest tillage operations to destroy and bury residues are one means of destroying many of
Adult tobacco hornworm. Photo courtesy of www.ipmimages.org.
Organic Tobacco Production