Emulsifier surfactant-oil combinations with tralkoxydim

Abstract

Research was conducted at the Brandon Research Station to determine the optimum oil-emulsifier surfactant ratio for each of two oil-emulsifier surfactant pairs for use with tralkoxydim. A series of adjuvants containing 8.5, 17, 34, and 68% emulsifier surfactant (by weight) plus oil were formulated for a petroleum oil (PO)- or methylated seed oil (MSO)-based adjuvant. Tame oats (Avena sativa L.) fresh weight was used to determine percent control as the indicator for phytotoxicity. PO (Sunoco 11 N oil) adjuvants had greater emulsion stability ratings than MSO adjuvants. Emulsion stability was not related to oats control, as MSO adjuvants enhanced tralkoxydim phytotoxicity more than PO adjuvants. Oats control increased as adjuvant volume increased from 0.25 to 2.0% (vol/vol) of the spray solution for either PO- or MSO-based adjuvants. For PO-based adjuvants, the adjuvant containing 34% emulsifier surfactant (by weight) and used at 0.5% (vol/vol) was as effective as the adjuvant containing 17% emulsifier surfactant and used at 1.0%. However, for MSO-based adjuvants, 17% emulsifier surfactant content was as effective as higher emulsifier surfactant content. Oats control did not correlate with the amount of oil in the spray solution. These data indicate that the optimum oil-emulsifier surfactant ratio will vary for each particular oil-emulsifier surfactant pair. Key words: Tralkoxydim, adjuvant, adjuvant volume, methylated seed oil, petroleum oil, surfactant content