Effects of Chlorsulfuron or 2,4-D upon Diclofop-Methyl Efficacy in Oat (Avena sativa)

Abstract

Oat (Avena sativaL. ‘Elgin′) seedlings were treated with combinations of diclofop-methyl {methyl ester of 2-[4-(2,4-dichlorophenoxy)phenoxy] propanoic acid} and 2,4-D amine [dimethylamine salt of (2,4-dichlorophenoxy) acetic acid] or diclofop-methyl and chlorsulfuron {2-chloro-N-[[(4-methoxy-6-methyl-1, 3, 5-triazin-2-yl)amino] carbonyl] benzenesulfonamide} to determine the effect of the added herbicide on diclofop-methyl activity. Diclofop-methyl applied alone at rates of 0.50, 0.75, and 1.00 kg/ha killed the oat plants 14 days after treatment. When 2,4-D amine at 0.74 and 1.11 kg/ha was combined with diclofop-methyl, the phytotoxicity of diclofop-methyl was reduced. An antagonistic interaction between diclofop-methyl and 2,4-D was detected. Chlorsulfuron, applied alone, at 20, 40, or 60 g/ha did not affect the growth of oats. Chlorsulfuron additions did not affect the activity of diclofop-methyl. Diclofop-methyl reduced oat coleoptile elongation. Equimolar concentrations of diclofop-methyl and 2,4-D at or above 1 μM significantly reduced the 2,4-D response. A ten-fold increase of either 2,4-D or diclofop-methyl, above an equimolar concentration of 1 μM, significantly enhanced the effect of the herbicide being increased.

Effect of diclofop‐methyl and 2,4‐D on transmembrane proton gradient: a mechanism for their antagonistic interaction

“…5A). Such an effect extended over 24 h tnay explain the action of auxin-like compounds, 2,4-D and dicamba, in partially overcoming the inhibitory effect of DM in the Avena straight growth test (Hall et al 1982, Shitnabukuro et al 1978. The 2,4-D analog, 2,6-D, which failed to stitnulate proton excretion (Fig.…”

“…Therefore, simultaneous field application of DM and 2,4-D to control wild oat and broad-leaved weeds in wheat is not recommended due to the reduced phytotoxicity of DM (O'Sullivan et al 1977, Todd andStobbe 1974). The antagonism is reciprocal and has been demonstrated in tissue culture (Shimabukuro et al 1986), oat coleoptiles (Hall et al 1982, Shimabukuio et al 1978 and whole plants under greenhouse and field eonditions (Olson and Nalewaja 1981).…”

“…In intact plants the sensitive sites of action appear to be the rapidly dividing and elongating cells in the meristematic regiotis (Donald et al 1982, Hoerauf atid Shitnabukuro 1979, Morrison et al 1981. The antagonistic interaction between DM and 2,4-D is not attributable to changes in the rate of DM absorption, translocation or tnetabolism and detoxication (Hall et al 1982, Shimabukuro et al 1986). Therefore, the tnechanism for the interaction between DM and 2,4-D is still unknown.…”

Diclofop‐methyl antagonism by broadleaf weed herbicides: the importance of leaf expansion rate

“…Thus chlorophenoxy herbicide antagonism of diclofopmethyl activity may be due to effects on H* efflux from cells. Chlorophenoxy herbicides can cause a substantial decrease in diclofop-methyl phytotoxicity (Hall et al, 1982a;Kafiz et al, 1989). If diclofop-methyl antagonism by chlorophenoxy herbicides is primarily due to their auxin-like effects on H* extrusion or other processes, then inhibition of auxin action must be an important factor in the mode of action of diclofop-methyl.…”

Selective control of perennial grasses in Kentucky bluegrass (Poa pratensis L.) turf with chlorsulfuron

“…oats{Hall et al, 1982). Studies conducted at IO\va State University have shown that chlorsulfuron can be applied to Kentucky bluegrass at rates as high as 280 g/ha without any phytotoxic effects.…”