Impacts of lower-leaf removal timing, number, and nitrogen application to flue-cured tobacco

The removal and exclusion of lower-stalk tobacco (Nicotiana tobacum L.) from harvest continues to be encouraged by industry. Very little information addresses the timing aspect of leaf removal, specifically when it occurs near floral initiation. Research was conducted in 2016 and 2017 to evaluate each possible treatment combination of two lower-leaf removal programs (0 and 8 leaves/plant), three removal timings (2 wk before topping, at topping, and 2 wk after topping), and two N application rates (0 and 10 lb/ac). Soil plant analysis development (SPAD) measurements consistently revealed a lighter leaf color in treatments consisting of leaf removal 2 wk before topping, regardless of N application rate. Foliar cured leaf samples from upper-stalk positions also contained less total N when eight leaves (2.25%) were removed relative to zero leaves (2.32%). These results indicate that subsequent N fertilizer application did not supply N as efficiently as remobilization from lower, older leaves. In the 8-leaf removal program, both cured leaf yield and value declined by 27% relative to the 0-leaf program. Despite significant losses in yield and value, the 8-leaf program completely eliminated lug grades of tobacco. Leaf removal timing and N application rate did not affect yield, quality, value, or grade distribution. Our results suggest that there is no agronomic or cost to removing lower leaves 2 wk before or after topping; however, commercial farmers may find this information to be of use from a time management perspective, should they decide to implement this practice.