Entrapment of herbicides in starch for spray applications
1988
Trimnell, D. | Shasha, B.S.
Sprayable controlled-release formulations were made with the herbicides trifluralin, 2,4-D ester, alachlor and butylate. Aqueous dispersions of gelatinized cornstarches or flours containing herbicides were sprayed and dried to water-resistant films that entrapped the herbicide. Formulations containing 3% Miragel, 3% cooked pearl, or 7% pregelatinized corn flour and one tenth these levels of active ingredient (a.i.) provided as emulsifiable concentrations had stable viscosities in the 75-260 cP range over 24 hours. The best entrapment was obtained by cooking 3% starches or flours at least 30 min at 100.degree. C and dispersing the emulsifiable concentrates into the cooled whole pastes. Dried formulations based upon 3% miragel entrapped 88% trifluralin, 96% 2,4-D ester, 75% alachlor, and 9% butylate. Butylate retention increased to 42% with 6% Miragel that had been pyrolyzed 1 h at 200.degree. C. Release of trifluralin from Miragel in the presence of .alpha.-amylase solution increased with decreasing particle size and increasing level of active ingredient.
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