Herbicidal Activity of Starch Encapsulated Trifluralin

Abstract

The formulation of trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) encapsulated within a starch granule can reduce the loss in activity associated with the delayed incorporation of the emulsifiable concentrate formulation of trifluralin. Good weed control and high soybean [Glycine max(L.) Merr. ‘Wells II’] yields were obtained when a starch formulation of trifluralin was applied in the fall and incorporated at planting time the following spring. The cultural practices of shallow incorporation, delayed incorporation, and/or midseason cultivation intensified the weed control provided by a starch formulation of trifluralin. The adsorption of additional trifluralin onto the granule surface, cross-linking starch xanthate with a weak oxidant, and mixing granules with different release rates also increased initial control. Granules produced by the starch-calcium and starch-borate processes exhibited many of the same characteristics of granules produced by the older starch xanthate process, but are much less expensive to produce and do not require the use of the toxic carbon disulfide in the encapsulation process. The combination of an appropriate starch formulation of trifluralin with proper cultural practices provided good weed control from fall and spring applications of trifluralin.