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50th TWC, Tob. Work. Conf., 2022, abstr. 38

Battling MH residues with alternative application methods

North Carolina State University, Raleigh, NC, USA

Maleic hydrazide (MH) remains a critical component of sucker control programs in US tobacco production systems. However, MH residues remain a strong critique of tobacco sourced from the region. The purpose of our research was to evaluate high-output nozzles with ultra-coarse droplet size (>650 microns) for their impact to sucker control efficacy and cured leaf residues in three stalk positions (cutter, leaf, and tip). Three ultra-coarse nozzles were selected: TDXL (air-inducted venturi assembly), AITTJ (air-inducted turbo twinjet), and ¼TTJ (TurfJet wide angle flat fan) and compared to a standard three-nozzle sucker control arrangement (outfitted with three solid cone nozzles) and a single solid cone nozzle. Each nozzle type and configuration was evaluated at 25 and 50 gallon/acre (GPA) solution volumes. A non-treated control was included to establish sucker control parameters but was not included in the data analyses. Sucker control was >97% among each treatment combination (nozzle type ˣ output volume); however, the TDXL-50 GPA, AITTJ-50 GPA, AITTJ-25 GPA, and ¼TTJ-25 GPA increased sucker control to >99%.  Cured leaf MH residues were similar among nozzle types in the cutter and leaf stalk position, but were lowest in tip leaves when the AITTJ and ¼TTJ were used. Cured leaf MH residues were also greater within the 25 GPA solution volume than the 50 GPA volume across each of the three stalk positions. Our results suggest that growers might utilize new nozzle technology in an attempt to lower MH residues in cured tobacco, but they should not change the recommended solution output volume of 50 GPA. (Reprinted with permission)