Published online by Cambridge University Press: 12 June 2017
Soil moisture, relative humidity (RH), and the addition of bentazon were examined for effects on absorption and translocation of 14C-imazethapyr in common ragweed. When common ragweed was growing under conditions of low soil moisture (-300 kPa), absorption of 14C-imazethapyr was reduced from 51 to 42%. Translocation of 14C-imazethapyr was not affected by soil moisture. In the absence of bentazon, absorption and translocation of 14C-imazethapyr was similar at 65 and 85% RH 48 and 168 h after treatment. Bentazon decreased absorption of 14C-imazethapyr from 61 to 26% at 65% RH and from 65 to 57% at 85% RH 168 h after treatment. Bentazon decreased translocation of 14C-imazethapyr from 35 to 9% at 65% RH and from 30 to 21% at 85% RH when averaged over time. This reduction in the absorption and translocation of 14C-imazethapyr when bentazon was added may result in a reduction in common ragweed control compared to imazethapyr alone when RH is 65% or lower.