UPTAKE, TRANSLOCATION, AND METABOLISM OF CHLORIMURON IN SOYBEAN (GLYCINE-MAX) AND MORNINGGLORY (IPOMOEA SPP)

The uptake, translocation, and metabolism of the ethyl ester of chlori muron in three soybean cultivars and two morningglory species was inve stigated. Soybean used included the normal cultivars 'Vance' and 'Esse x,' and the sulfonylurea-resistant cultivar 'W-20.' Entireleaf morning glory and pitted morningglory, both moderately tolerant to chlorimuron , were used. Twenty-day-old seedlings of all plant species were expose d to root-applied C-14-labeled chlorimuron for 6, 24, and 72 h. After 24 and 72 h, chlorimuron uptake was lowest in W-20 soybean and the two morningglory species. Translocation of root-absorbed chlorimuron to s hoots and leaves of all species was limited and it did not differ amon g species. The moderate tolerance of pitted and entireleaf morningglor ies to chlorimuron may be due to reduced herbicide uptake. The respons e of Essex and Vance soybean to chlorimuron was related to herbicide m etabolism. At 6 h after treatment with radiolabeled chlofimuron, Essex soybean metabolized the herbicide more rapidly than either W-20 or Va nce soybean. At 24 h and 72 h, Essex and Vance soybean metabolized chl ofimuron to the same extent. W-20 was not very efficient in metabolizi ng chlofimuron at any time after treatment and its resistance to chlor imuron is due to an altered target site.