The Effect of Suckercide Application Timing and Cultivar Maturity on Chemical Topping of Burley Tobacco

Experiments were initiated in 2015 to evaluate the efficacy of chemical topping for burley tobacco (Nicotiana tabacum L.). The major objectives for this study were to determine the optimum timing of suckercide application and appropriate cultivar maturity for effective chemical topping. Burley tobacco cultivars TN 90 (medium maturity), KT 210, and KT 215 (late maturity) were chemically topped at the 10% button, 50% button, and 10% bloom growth stages. The 10% button and 50% button application timings were best suited for chemical topping practices. Treatments that targeted the 10% bloom stage did not completely halt inflorescence growth; however, all application timings resulted in excellent sucker control. Both medium and late maturing burley cultivars proved to be acceptable for chemical topping methods; however, timing the suckercide application may be less difficult with later maturing cultivars. Chemically topped treatments generally resulted in shorter, narrower tip leaves than manually topped treatments. There were no significant differences in total yield of TN 90 when comparing tobacco that was manually topped at 10% bloom to tobacco that was chemically topped at 10% button, 50% button, or 10% bloom across all environments. In 4 out of 6 environments, total yield was not significantly different between manual topping and any chemically topped application timing in the late maturing burley cultivars; however, at least 1 chemically topped application timing had equivalent yield to manually topped tobacco in all environments.