Tomato Root Uptake of Carfentrazone

Fresh market tomato is an important and valuable crop in Florida, accounting for 630 million dollars farm-gate value, which was 45% of the total value of the U.S. crop in 2010. In order to maintain or increase its productivity, labeled herbicide alternatives to methyl bromide are important to limiting seed production of weeds emerging between the raised plasticulture beds. A study was conducted inside a greenhouse where carfentrazone was applied as a drench at 0.03125×, 0.0625×, 0.125×, 0.25×, 0.5×, 1×, 2×, 4×, and 8× and as a subsurface irrigation at 0.0625×, 0.125×, 0.25×, 0.5×, 1×, 2×, 4×, 8×, and 16× rates. The 1× rate equaled the maximum labeled rate of carfentrazone (35.1 g ai ha−1) that would be applied to an area of 0.360 m2. Both the drench and subsurface trials showed an increase in plant injury and reduced growth as the rate of carfentrazone increased. The drench trial, however, was observed to have higher visible injury and greater growth reduction (based on plant measurement) than the subsurface trial, when comparing similar rates. For the 1× rate of carfentrazone in the drench trial vs. the subsurface trial, injury was 66 and 24.5%, respectively. For the 1× rate the tomato plants had estimated growth, based on the curves fit for the data, of 4.8% vs. 39.9% for the drench and subsurface trials, respectively. The subsurface trial better represents what happens in the field when carfentrazone root uptake injury is observed since it is normally observed to be around 10% or less. This still leaves a level of concern; once a 10% injury level in the subsurface trial was estimated to have reduced tomato growth, fruit weight, and total shoot dry weight by 33, 15, and 9.5%, respectively. Nomenclature: Carfentrazone; methyl bromide; tomato; Lycopersicon esculentum L. El tomate fresco es un cultivo importante y valioso en Florida, representando 630 millones de dólares de valor a las puertas de las fincas, lo cual a su vez representó 45% del total del valor del cultivo en Estados Unidos en 2010. Con el fin de mantener o incrementar su productividad, los herbicidas registrados para este cultivo como alternativas a methyl bromide son importantes para limitar la producción de semillas de malezas que emergen entre las camas con cobertura plástica. Se realizó un estudio dentro de un invernadero donde se aplicó carfentrazone como “drench” a dosis de 0.03125×, 0.0625×, 0.125×, 0.25×, 0.5×, 1×, 2×, 4× y 8× y mediante irrigación subterránea a dosis de 0.0625×, 0.1