Soil Applied Maleic Hydrazide Does Not Suppress Tobacco Axillary Bud Growth

Abstract

Core Ideas Maleic hydrazide residues are a threat to the US tobacco industry. Alternative application methods could prove beneficial. Root absorption of maleic hydrazide appears to be limited. With an increasing focus on maleic hydrazide (MH) residues and the need to sufficiently control axillary bud (sucker) growth, flue‐cured tobacco (Nicotiana tabacum L.) producers would benefit from an alternative to the conventional foliar application method of the plant growth regulator. Research was conducted in four North Carolina environments from 2014 to 2015 to quantify the efficacy of soil applications of MH. Two rates of MH were selected (2.25 and 4.50 lb a.i./acre) and were applied in combination with one of three sucker control programs: foliar MH preceded by foliar flumetralin (F treatment), soil MH preceded by foliar flumetralin (SF treatment), or soil MH preceded by foliar fatty alcohol (SFA treatment). Ranging from 95 to 100%, sucker suppression was greatest in F treatments. In two Coastal Plain environments, the control in SF treatments was similar to that of F treatments; however, in the two Piedmont environments, the control was reduced by 30 to 50%. Sucker suppression was lowest in SFA treatments, particularly in the Piedmont environments, thus indicating that flumetralin was the likely source of suppression in SF treatments. No differences were observed between the two MH application rates evaluated. Given the observations of this study, it is unlikely that a soil application of MH will serve as an effective sucker control alternative to the standard foliar application used at present by commercial growers.