Glyphosate [N-(phosphonomethyl)glycine] was separated from its potential metabolites, aminomethylphosphonic acid, glycine, and sarcosine by using 500 μm-thick cellulose plates developed with ethanol:water:15 N NH4OH:trichloroacetic acid (TCA):17 N acetic acid (55:35: 2.5:3.5 g:2, v/v/v/w/v with v in ml). This TLC system separated impurities from the 14C-glyphosate standard and glyphosate from possible metabolites in treated field bindweed (Convolvulus arvensis L.).

The initial metabolism of acetochlor [2-chloro-N-(ethoxymethyl)-N-(2-ethyl-6-methylphenyl)acetamide] in tolerant and susceptible plants was examined to determine if metabolism is a factor in the selective phytotoxicity of this herbicide. Six crop and ten weed species were used. In every case acetochlor was converted initially to thioether conjugates. In thirteen of the species, initial conjugation was with glutathione (GSH). The homoglutathione (hGSH) conjugate was formed in three legumes. Tolerant plant seedlings metabolized acetochlor more readily than susceptible plant seedlings. Based on these results, acetochlor detoxification is a primary factor in the selective phytotoxicity of this herbicide.

Field experiments were conducted from 1997 to 1999 at Ejea and at Valdegon (Spain) to study weed control and tolerance of direct-seeded pepper ‘Agridulce SIA’ to clomazone alone or with linuron, napropamide, or pendimethalin. The main weeds at Ejea were redroot pigweed, Diplotaxis erucoides, common purslane, and ivyleaf speedwell, while at Valdegon they were Solanum physalifolium and common purslane. Pepper was tolerant to clomazone applied at 0.18 kg ai/ha, but weed control was less than 77%. Increasing the rate of clomazone to 0.36 kg/ha controlled weeds at least 85% and did not injure pepper. Clomazone at 0.54 and 0.72 kg/ha injured pepper 6 wk after planting (WAP), but plants recovered and the dry weight and yield of paprika were not affected. Napropamide at 2.03 kg ai/ha applied with clomazone improved the control of D. erucoides. Addition of pendimethalin at 0.17 to 0.25 kg ai/ha to clomazone did not improve weed control and increased pepper injury 6 WAP in 1 of 2 yr, but yield was not affected. Linuron at rates ranging from 0.08 to 0.13 kg ai/ha used in combination with clomazone provided complete weed control but injured pepper the most (34 to 88%) and reduced pepper stand by 50% in 1 yr.