SOIL PLACEMENT STUDIES WITH EPTC AND OTHER CARBAMATE HERBICIDES ON AVENA SATIVA*

Abstract

Sludics wcrr conductpd to determine the cflTrct of soil placcmrni of EPTG. di-allaic and propham (IPCl on oau. A technique called the 'envelope method' vras used [o make pt.>isiblc the separate exposure of coleoplilc^, seed and roots of emerging oai ser^lingi to the various lierbirides. HPTC at 10 ppin, (ii-allatc at '20 pjini and propham at 3-0 ppm were all extremely toxin to oats through colcoptilc uptake. Penetration of roots intd treated soil, however, resulted in very little injury to the plant. Plants grew undamagefl from seeds which had liecn allowed to imbilx-for 3G hr in soil treated with EPTC at 10 ppm.Studies using radioactive EPTC indicated ihat both roots and coleoptifes readily absorbed EPTC from soil and that measurable amounts translocated both upward and downward. Under certain circumstances, as muth unmctabolized EPTC could accumulate in roi»ts a.* in shoots, even though less toxiciiy was noted from root exposure. This would iiuliratt; thai the differential sensiiiviiy tx-iween roots and nhoots is not due to difference!! in uptake, tranBlocation, or metabolic hreakdown. Rather it appears that the shoot is Ihe major site of lethal action of EPTC in oaM. £lutie du pleuemtnt dt I'EPTCel d'autns carbamatts dans It tol ante Avena saliva Resume. I.Vtudc avait pour but dc determiner faction du placcmmt dans lc so) d'EPTC, di-aliate et propham (lFC), sur I'a^-oine. Une technique d^nomm^ 'mithode dc I'envcloppr' fut utilis<4r pour exposcr sipan^mmt atix herbicides les colioptiJcs, lea graines et Irs racines des pinntules germantcs d'avoine. L'EPTC k 1 p|)m, le di-allate h 2 ppm ct Ir propliam a 3 ppm. atisorbis par la coli^optile, furent rxtrrnit-mcn t loxiquespour I'avoinr. CrjirrKlanL la p^n<5tration des racines duns un sol traitiS n'a quc pcu eiidommagi la plantc. I ict graines piar^os pendant 36 heures dans un sol traiti avec 1 ppm d'EPTC ont produit des plantes normalrs.Des Etudes utilisant I'EPTC: radioactif ont di^montri que lc produit est rapidemrnt absorb^ du »ol par les racines et par les coleoptilcs. et que des quantity mesurables sont transpc)rt<^» vers le haut et le bas dc la plante. Dans certaines conditions des quantitii semblabirs d'EPTC non m^tabolis^ ont pu s'accumuler dans les racines el dans le> tigcs, birn que l'exposition drs racines soit moins toxiquc pour la plaiitc. Ceci paralt indiquer qur la sen.iibilit** dillferentr des racines ct dcs tigrs n'cst pas due h des dilTevcnces d'absorption, de transport ou dc degradation mdtaboliquc. II scmblerait philoi que la lige est le lieu primordjal dc I'aciion litale de i'EPTC sur Tavoinc.cam Ein/bus de\ Eiiani:uhens ivn EPTC und anderen harbamattn iti oerxkiedne Bodrnsfhiihlcn auf drrm Wirkung grgtnuhet Avcna s;ttiva

Effect of soil placement and shoot uptake of prometryne and terbutryne on peas

“…Dawson (1963) showed similar results with EPTC. Appleby, Furtick & Fang (1965) reported similar effects with EPTC, di-allate and propham. Prendeville (1968) found, however, that in maize the shoot region around the growing point and crown root node was most sensitive to propham, chlorpropham and EPTC.…”

Site of Uptake of Soil‐applied Herbicides*

“…This may be due to inherent resistance of sorghum roots to the herbicide, or to the fact that the bioassay was not extended over a longer period of time. Using radioactive EPTC, Yamaguchi (1961) and Appleby et al, (1965) found that absorption of this herbicide was by roots and shoots and translocation was upwards from roots to foliage and downward from foliage to roots. Appleby et al (1965) discovered no differences in uptake or metabolic degradation between the two zones; why EPTC was more toxic when the shoot rather than the roots was exposed to the compound is therefore still not clear.…”

“…Most of the published work on determination of the site of uptake of soilapplied herbicides by plants, has been conducted on carbamate-type herbicides such as isopropyl JV-phenylcarbamate (propham), 5-ethyl JVjV-dipropylthioIcarbamate (EPTC) and 5-2,3-dichloroallyl TVOV-di-isopropyl thi dear bam ate (diallate). Studies by Friesen, Banting & Walker (1962), Dawson (1963), and Appleby, Furtick & Fang (1965) on placement of these herbicides in soils indicated that they were primarily absorbed through the coleoptile of emerging grass seedlings. There was less effect on the plants when the root systems only were exposed to the herbicides.…”

“…Most research conducted on uptake by plants when herbicides are applied to the soil has involved use of monocotyledonous test species such as grasses and small grains (Friesen et al, 1962;Appleby et al,, 1965;Dawson, 1963;Parker, 1966). We studied the effect of placement of several herbicides in specific zones of soil on corn and on pea.…”

Site of Uptake and Action of Thiocarbamate Herbicides and Herbicide Antidotes in Corn Seedlings

“…A number of reports (1)(2)(3)(4)(5)(6)(7) have been concerned with the site of uptake of EPTC in various plant species. In some species root exposure to the treated soil gave more injury than shoot exposure and in other species shoot exposure gave more injury (1,5).…”