Absorption and translocation of the 14C-labeled herbicide 2-(3,4-dichlorophenyl)-4-methyl-1,2,4-oxadiazolidine-3,5-dione (bioxone) in cotton (Gossypium hirsutum L. ‘Acala 4-42-77′) were studied using autoradiography and counting. Foliar penetration and acropetal distribution of 14C occurred within 3 hr and increased with time. No basipetal translocation of 14C out of treated leaves was detected 6 days after treatment. Radioactivity first occurred in the leaf veins, then more generally in interveinal tissues distally from the point of application. Absorption into roots of 30-day-old plants via nutrient solution was rapid; translocation into stem and leaves occurred 12 to 24 hr after treatment. Translocation of 14C was more rapid in 40-day plants. Radioactivity in leaves of root-treated plants was first located in the veins, then distributed throughout with accumulation of 14C in lysigenous glands and leaf margins. Little 14C moved into young growing points; most accumulated in older leaves. Plants treated with heterocyclic ring-labeled and phenyl ring-labeled bioxone-14C had similar distribution patterns of 14C, characteristic of compounds which move only in the apoplast.

The absorption and translocation of 14C in 14C-ring-labelled 4-(2,4-dichlorophenoxy)butyric acid (2,4-DB) at 1 and 7 days after foliar treatment of soybean [Glycine max (L.) Merr.] and cocklebur (Xanthium sp.) were investigated at 3, 5, 7, and 11 weeks after planting by means of radioautography and standard radioassay methods. Partitioning of radioactivity varied with plant age and with treatment time. Although a species difference was not observed in the total uptake of 2,4-DB, the rate of penetration of the herbicide was greater in cocklebur than in soybean. The 2,4-DB was retained in the treated leaf and was not translocated to other plant parts. Translocated radioactivity occurred principally in actively growing parts of both species, but only trace quantities were detected in soybean. No radioactivity was detected in the lower leaves of either plant. Plant response to 2,4-DB may be partially explained on the basis of differential penetration and translocation.

Single applications of 4.48 and 22.4 kg/ha of the ester formulation of (2,4,5-trichlorophenoxy)acetic acid (2,4,5-T ester), 2,4,5-T amine, and 2-(2,4,5-trichlorophenoxy)propionic acid (silvex) to the ground cover and soil under apple (Malus sylvestris Mill.) trees significantly reduced the proportion of broadleaf plants to grasses. After six annual applications of these herbicides, the ground cover consisted of almost pure stands of grasses. Six applications of 2-sec-butyl-4,6-dinitrophenol (dinoseb) + oil at 4.2 kg/ha + 374 L/ha and five times this rate decreased the proportion of broadleaf weeds to grasses, but one application did not change the proportion. One and six annual applications of dinoseb amine at 16.8 and 84 kg/ha significantly reduced the percentage of broadleaf weeds. One application of 3-amino-s-triazole (amitrole) at 4.48 kg/ha and six annual applications of amitrole at 22.4 kg/ha significantly decreased the percentage of broadleaf weeds. Six annual applications of 2,2-dichloropropionic acid (dalapon) + dinoseb amine at 47.6 + 84 kg/ha significantly increased the percentage of broadleaf weeds, especially mouseear chickweed (Cerastium vulgatum L.) and red sorrel (Rumex acetosella L.). Six annual applications of ammonium sulfamate (AMS) at 168 and 840 kg/ha increased the proportion of grasses to broadleaf weeds as did a single application at 168 kg/ha. AMS caused phytotoxic symptoms on young apple replants at the 168-kg/ha rate and also on mature trees at the 840-kg/ha rate. No phytotoxic symptoms were noted with the other herbicides applied.