Differential Activity of Three Diphenyl Ether Herbicides

Abstract

The tolerance of four legume species to nitrofen (2,4-dichloro-phenyl-p-nitrophenyl ether), fluorodifen (p-nitrophenylα,α,α-trifluoro-2-nitro-p-tolyl ether), and oxyfluorofen [2-chloro-1-(3-ethoxy-4-nitro-phenoxy)-4-(trifluoro-methyl)benzene] was investigated both pre- and postemergence in the greenhouse. Seedlings of species that emerged most rapidly seemed to be most tolerant to preemergence herbicide applications. There was no direct relationship between preemergence and postemergence tolerance. Oxyfluorfen was found to be at least 10 times as active as the other two herbicides both pre- and postemergence. Field experiments were conducted at two locations in Indiana to test the effect of method of application on the activity and selectivity of fluorodifen and oxyfluorfen on soybean [Glycine max(L.) Merr. ‘Wayne’] and greenbean (Phaseolus vulgarisL. ‘Spartan Arrow’). Crop injury and grass weed control were reduced by incorporation of the herbicides 8 cm deep in a silt loam. Method of application did not affect the activity of the herbicides on a sandy soil low in organic matter. Soybean was more tolerant than greenbean to both herbicides when applied preemergence but oxyfluorfen was far more active than fluorodifen on both crops.

Uptake and Translocation of Nitrofen and Oxyfluorfen

“…Similar results were obtained for pea with both nitrofen and oxyfluorfen except that, being less sensitive, about 10 times more herbicide was required for pea than for sorghum to ob tain comparable levels of inhibition. These results agree with observations in the field where incorporation of fluorodifen and oxyfluorfen resulted in reduced injury to soybean and greenbean (6). Yih and Swithenbank (12) noted that incorpor ation of nitrofen and fluorodifen drastically reduced their ef fectiveness, probably by reducing the concentration of the herbicides in the shoot zone of the emerging weed or crop seedlings.…”

“…While the extent of movement in both soybean and greenbean was the same, apparently there was more absorption of both herbicides by soybean (F-value for species significant at 5% level). Since soybean is known to be more resistant to these herbicides than greenbean (6), other selectivity mechanisms besides absorption and translocation must be responsible for this difference.…”

Control of Quackgrass (Agropyron repens) in Soybeans (Glycine max) with HOE 29152

“…There are several chemicals similar to HOE 29152 that have herbicidal activity; however, none of these has been re ported to control quackgrass. Soybeans are tolerant to postemergence applications of these herbicides (1,5), and herbi cide movement is minimal in treated plants (6,12).…”

Oxyfluorfen Under Clear Polyethylene Film Controlled Weeds in Transplanted Cucurbits

“…In the fourth reported case of injury, oxyfluorfen was incorporated rather than applied to the soil surface, and injury was slight (19). Decreased herbicide injury and weed control efficacy when oxy fluorfen was incorporated have been reported for several crops (8,9,24).…”