FACTORS AFFECTING THE SELECTIVITY OF 2,3‐DICHLOROALLYLDIISOPROPYLTHIOLCARBAMATE (DI‐ALLATE) AGAINST AVENA SPP. IN WHEAT AND BARLEY

Abstract

A series of pot experiments has been undertaken to assess the selectivity of 2,3-dichloroallyldiisopropylthiolcarbamate (di-allate) against Avena spp. in wheat and barley. It is shown that depth of incorporation, depth of sowing, variety and temperature can all influence the degree of selectivity. When di-allate is incorporated deeply before sowing, there is good selectivity against Avenafatua L. (wild oat) in barley, but the order can be influenced by the depth at germination of both crop and weed, since the susceptibility of both species increases wilh increasing depth. Wheat does not exhibit the same response to depth of sowing but variety and temperature are important; the variety 'Svenno' is particularly susceptible, and both 'Svenno' and 'Atle' are much more susceptible at 20" C than at 10'' C. As A. fatua is slightly more susceptible at 10" C than at 20° C, selectivity is greater at the lower temperature.Shallow incorporation of di-allate after sowing gives a much more general selectivity in both barley and wheat, but there is still some element of risk in wheat. Whereas for barley a layer of only 0 5 in. of untreated soil above the seed is adequate protection against damage by di-allate, t-l-.5 in. of untreated soil may be required above the seed of wheat, depending on variety and temperature. The success of shallow incorporations is explained on the basis that the most sensitive region of the plaiil is the lO-l.^' j mm above the coleoptile node, whicb includes the stem apex and developing leaf tissue. This region is moved up in the soil rapidly in Avena spp. by elongation ofthe 'mcsocotyl', whereas in wheat and barley, the stem apex is only moved up considerably later by elongation ofthe intemode above the coleoptile node.2,3,3-Trichloroallyldiisopropylthiolcarbamate (tri-allale) as compared to di-allate has a greater selectivity in barley wben the compounds are incorporated deeply; also it has greater selectivity in both wheat and barley when shallowly incorporated after sowing. FacteuTs injiuenfant ta selectivity du diiiopropyilhiolcarbamale de 2,3-dichtoroaltj/te {di~attate) apptiqui sur bti et sur orge contre Avena spp.Resum^. Une s^rie d'exp^riences en pots est d^crlte, dans laquelleest ^tudi^e la si^lectivitd u diisopropyltbiolcarbamate de 2,3-dichloroallylc (di-allate) appliqu^ dans te h\€ el I'orge conlre Avena spp. L'autcur d^niontre que la profondeur d'incorporation, la profondeur dc semis, la varidt^ et la temperature peuvent influeiicer le degr^ de selectivity. Qiiand le di-allatc est incorpor^ profbnd^ment avanl un semis d'orge pour latter centre la folle avoinc {Avenafatua L.) il fait preuve d'une bonne selectivity, mais les r^sultats peuvent etre influences par la profondcur de germination dc la plante cultiv^e et de I'adventice car la sensibility dc ces deux esp^ces augmente avec la profondeur de semis. Le bl^ ne r^pond pas de la meme maniere a la profondeur de semis mais les facleurs vari^te et temperature sont importants; la variete Svenno csl particulierement sensible et les varietes A...

Étude Du Comportement Du Pebc Et De Son Utilisation Pour Le Désherbage Des Betteraves

“…A la dose de 1,4 kg/ha par exemple, la levee est reduite de 22% par rapport au temoin non traite, tandis que I'allongement de la coleoptile est reduit de 88% (moyenne pour les trois sols ctudies). Cette observation est a rapprocher des etudes realisees sur des herbicides voisins, le di-allate et l'EPTC, montrant que les graines de graminees n'absorbent pas ces herbicides, que les racines en absorbent relativement peu et que la coleoptile est le site principal de l'absorption et de Faction letale (Appleby & Furtick, 1962;Dawson, 1963;Parker, 1963).…”

“…L'incorporation profonde a tres nettement reduit l'activite herbicide du PEBC, sans doute en diluant l'herbicide dans une couche de terre plus epaisse. Le PEBC, comme d'autres carbamates \'oisins tels que l'EPTC ou le di-allate, est probablement absorbe par la tige des plantes au moins autant, sinon plus, que par les racines (Appleby & Furtick, 1962;Parker, 1963), et peut-etre aussi a l 'etat de vapeur {Yamaguchi, 1961). L'enfouissement du produit dans le sol a proximite des racines ne peut, dans ce cas, augmenter son activite, et l'incorporation ne pourrait etre justifiee que pour soustraire l'herbicide aux faeteurs de degradation.…”

SHOOT ZONE UPTAKE OF SOIL‐APPLIED HERBICIDES IN PISUM SATIVUM L.

“…Friesen, • Present address: School of Biological and Environmental Studies, The New University of Ulster, Coleraine, Co. Londonderry, N. Ireland. Banting & Walker (1962) showed that grass species differed in their sensitivity to localized placement of 5'-(2,3-dichloroallyl)-jVjV-di-isopropylthiolcarbamate (di-allate) in the shoot zone, while Parker (1963) demonstrated that in Avena spp. the base of the coleoptile was the most sensitive zone to di-allate.…”

Factors Affecting the Activity of Di‐allate and Tri‐allate

“…Spring wheat (Triticum aestivum L.) is less susceptible to injury from di-allate or tri-allate than oats but wheat can be seriously damaged if sown in treated soil. Injury to wheat can be avoided or reduced, however, if the seeds are planted 1 -3 cm or more below a layer of treated soil, at rates lethal to Avena fatua (Friesen gi a/., 1962;Parker, 1963). These differences have been explained on the basis that in wheat the stem apex is moved into the treated layer of soil at a later stage than in A. fatua (Parker, 1963).…”