CORESTA Congress, Quebec, 2014, Agronomy/Phytopathology Groups, AP 42

The effect of conveyor use during sucker control application in North Carolina produced flue-cured tobacco

North Carolina State University, Raleigh, NC, U.S.A.

With an ever increasing focus on complete sucker control and maleic hydrazide (MH) residue in US produced flue-cured tobacco, current research efforts have been focused on practical application alternatives for producers. Initiatives have included the evaluation of reduced rates of applied MH, a larger emphasis on fatty alcohol and flumetralin based products, the screening of off-label compounds, and investigations into alternative application equipment. In 2011, conveyors (hooded spray shields) were introduced to US producers in the hope that labelled sucker control material efficacy would improve, MH residue could be reduced, and/or that less total product could be applied per hectare.

Research was initiated that same year to quantify the effects that a more concentrated application pattern using conveyors might have. Three sucker control materials (contact, flumetralin, and MH) as well as combinations of flumetralin and MH were evaluated with standard three-nozzle assemblies and with conveyors. Specific treatments evaluated included four applications of fatty alcohol materials (13.48/16.85/16.85/16.85 kg a.i. ha-1), recommended rates of flumetralin (0.67 kg a.i. ha-1), split applications of flumetralin (0.67 kg a.i. ha-1/0.34 kg a.i. ha-1), tank mix applications of flumetralin (0.67 kg a.i. ha-1) and MH (1.68 kg a.i. ha-1), and various rates of MH (0.56, 1.12, 1.68 kg a.i. ha-1). All compounds were evaluated with and without conveyors and at two different application volumes (327 and 467 L ha-1). Following final harvest, percent sucker control, green sucker weight per plant, sucker number per plant, green weight per sucker, yield, quality, and crop value were assessed.

The use of conveyors resulted in sucker control similar to, but never better than, that observed with standard three-nozzle assemblies. Additionally, the use of conveyors did not reduce MH residues when compared to three nozzle arrangements nor did it allow for reduced application rate or solution volume of any the materials evaluated.