Research was conducted to evaluate residual activity of herbicides applied postemergence (POST) and preemergence (PRE) for red morningglory control. Atrazine at 2.24 kg ai/ha controlled 30- to 60-cm red morningglory 78% 10 d after treatment (DAT) but control was greater for carfentrazone at 0.035 kg ai/ha, diuron plus hexazinone at 1.57 0.44 kg ai/ha, flumioxazin at 0.14 kg ai/ha, and sulfentrazone at 0.32 kg ai/ha (88 to 93%). At 28 DAT control with diuron plus hexazinone, flumioxazin, and sulfentrazone, reflective of both the initial POST control and soil residual activity, was equivalent to that of atrazine at 3.36 kg/ha (92%), but control was 34 to 66% with carfentrazone at 0.009, 0.018, and 0.026 kg/ha, hexazinone at 0.56 kg/ha, pyraflufen at 0.007 and 0.015 kg ai/ha, and trifloxysulfuron at 0.016 kg ai/ha. In another study to evaluate residual control with soil-applied herbicides, red morningglory was controlled at least 87% 35 DAT with atrazine at 2.24 kg/ha, diuron plus hexazinone at 1.57 0.44 kg/ha, flumioxazin at 0.14 kg/ha, sulfentrazone at 0.16 kg/ha, and metribuzin at 1.68 kg ai/ha. Control 35 DAT was 78% for atrazine at 1.12 kg/ha, 84% for diuron plus hexazinone at 1.05 0.30 kg/ha, and 63% for flumioxazin at 0.07 kg/ha. By 49 DAT only sulfentrazone controlled red morningglory 80% or more and by 63 DAT, control with sulfentrazone at rates of 0.21 kg/ha and higher was 83 to 88%. At 77 DAT sulfentrazone at 0.21 kg/ha controlled red morningglory 78% and no other herbicide treatment provided more than 46% control. In another study red morningglory control did not change from 49 to 63 DAT when sulfentrazone at 0.28 to 0.42 kg/ha was applied PRE following trifluralin preplant incorporated (PPI), but control decreased from 49 to 63 DAT when sulfentrazone was incorporated with trifluralin.
Nomenclature: Atrazine; diuron; carfentrazone; flumioxazin; hexazinone; metribuzin; pyraflufen; sulfentrazone; trifloxysulfuron; trifluralin; red morningglory, Ipomoea coccinea L