A synergistic interaction occurred when sugarbeets (Beta vulgaris L. ‘Mono-Hy Al’) were treated with mixtures of ethofumesate (2-ethoxy-2,3-dihydro-3,3-dimethyl-5-benzofuranyl methanesulphonate) and desmedipham [ethyl m-hydroxycarbanilate carbanilate (ester)]. Depending on the stage of weed growth synergistic interactions were also observed on two weed species: wild mustard [Brassica kaber (DC.) L.C. Wheeler ‘pinnatifida’ (Stokes) L.C. Wheeler] and wild oat (Avena fatua L.). Desmedipham penetrated the foliage more slowly than did ethofumesate. The rate of desmedipham penetration was positively correlated with the concentration of its formulants (solvents and adjuvants) in the spraying emulsion, and to a lesser extent with the formulants of ethofumesate. Increasing the spray volume also increased desmedipham penetration. None of these factors affected penetration by ethofumesate. 14C-labeled ethofumesate and desmedipham did not translocate out of treated leaves regardless of the concentration of formulants or active ingredients. These data suggest that the synergistic interaction is mainly due to the increased penetration by desmedipham when applied with ethofumesate.

The persistence of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] and cyanazine {2-[[4-chloro-6-(ethylamino)-s-triazin-2-yl] amino]-2-methylpropionitrile} both applied at 2.24 and 4.48 kg/ha was studied in the field on two soils. A greenhouse bioassay using cucumber (Cucumis sativus L. ‘Wisconsin SMR-18′) showed no reduction in growth when plants were grown in soil taken from cyanazine and atrazine treatments at the end of the season. Similarly, fall-sown rye (Secale cereale L.) was not injured. The yields of transplanted tomatoes (Lycopersicum esculentum L. ‘Campbell 28′) and transplanted watermelons (Citrullus vulgaris ‘Crimson Sweet’) were not significantly reduced when grown 1 yr after the initial application of either herbicide.