Rates Of Trifluralin Research Articles

Control of Green Foxtail in Wheat with Trifluralin

Field experiments were conducted to study the competitive ability of green foxtail(Setaria viridis(L.) Beauv.) with wheat(Triticum aestivumL.) and the feasibility of usinga,a,a-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine (trifluralin) for the selective control of green foxtail in wheat. Rates of 0.56 to 0.84 kg/ha of trifluralin gave 90 to 100% control of foxtail when growing in competition with wheat. Wheat tolerated rates of trifluralin up to 2.24 kg/ha, the maximum rate used, without injury or reduction in crop yield, when the herbicide was applied and incorporated to a shallow depth 1 day after seeding. A semidwarf and a tall variety of wheat were not affected by trifluralin treatments. Green foxtail had a relatively low competitive ability, and wheat plants suppressed foxtail to a marked degree under normal growing conditions. However, suppressed plants still produced sufficient seed to insure a dense infestation of foxtail plants in the succeeding year. Further, when wheat was grown under less competitive situations, green foxtail resulted in significant reductions in crop yield. It was concluded that green foxtail is an “opportunist-type” weed.

Effects of Trifluralin on Growth, Nodulation, and Anatomy of Soybeans

Effects ofα,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine (trifluralin) rate and placement in soil on growth and anatomy of soybeans (Glycine max(L.) Merr.) were studied in greenhouses. In 7-week-old plants, trifluralin caused pronounced changes in number and organization of palisade cells in leaves. In fourth internodes, xylem elements of treated plants were less organized and walls of pericycle fibers were extremely thick compared to those of untreated plants. There was starch accumulation in nodules and in xylem elements of the upper root, and binucleate and trinucleate cells were present in tips of tap and lateral roots of treated plants. The effects were more pronounced as rate of trifluralin was increased from 0.36 to 0.74 and to 1.1 kg/ha and when trifluralin was incorporated into the 5 to 15-cm depth rather than the top 5 cm of soil. However, occlusions of xylem vessels in lateral and tap roots were most pronounced at 0.74 kg/ha. Plant topgrowth was reduced more when trifluralin was incorporated into the bottom 10 cm of soil, but root growth inhibition was not affected by trifluralin placement. Trifluralin reduced nodulation of soybeans and seemed to inhibit utilization of cotyledonary reserves and redistribution of organic and mineral constituents of unifoliolate leaves.

Selective Action of Trifluralin for Control of Green Foxtail in Wheat

The selective action of α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine (trifluralin) for the control of green foxtail(Setaria viridis(L.) Beauv.) in wheat(Triticum aestivumL.) was studied. Seedlings of both species, especially in the early stage of growth, were particularly susceptible to herbicide applied in the region of the coleoptile node. Selective control with trifluralin was possible, however, because of the morphological differences between the seedlings of the two species. Thus, the sensitive coleoptilar node area of green foxtail was located at a depth of less than 1 cm from the soil surface regardless of planting depth. The coleoptile node of wheat remained closely associated with the caryopsis. When a protective band of untreated soil was used to separate the caryopses from a 5-cm band of surface soil containing 1.12 ppmw of trifluralin, the shoot growth of wheat was normal. Much lower rates of trifluralin effectively controlled green foxtail, as surface or subsurface placement of a 1.3-cm layer of soil containing 1.12 ppmw of chemical above the foxtail caryopses completely inhibited shoot development. In addition to the differences in morphological development between the two species, the fact that green foxtail was considerably more susceptible to trifluralin than wheat was considered as an important factor contributing to the selective control.

Chemical control of weeds in tobacco in northern New South Wales

Herbicides were tested for weed control in tobacco in northern New South Wales at two sites in 1964-65 and 1965-66, and at one site in 1966-67. Herbicides used were diphenamid (N, Ndimethyl- 2, 2-diphenylacetamide) and trifluralin (a,a,a-trifluro-2, 6-dinitro-N, N-dipropyl-p-toluidine) in 1964-65, and trifluralin, benefin (N-butyl-N-ethyl-a,a,a-trifluro-2, 6-dinitro-p-toluidine), DCPA (dimethyl 2, 3, 5, 6 tetrachloroterephthalate), and EPTC (ethyl N, N-di-n-propylthiol-carbamate) in 1965-66. All were incorporated with spike tooth harrows. Various rates of trifluralin and benefin were compared using spike tooth harrow and disc harrow incorporation in 1966-67. Trifluralin at 0.37 to 1.0 lb active ingredient (a.i.) an acre and benefin at 0.75 to 1.8 lb a.i. an acre on a coarse sandy soil, and 2.0 lb a.i. an acre on a sandy loam soil gave good control of weeds without adversely affecting the yield or quality of cured tobacco. Some indications of phytotoxicity to tobacco occurred with trifluralin rates of 1.5 to 2 lb a.i. an acre and a benefin rate of 3.6 lb a.i. an acre. Method of incorporation produced no difference in weed control in 1966-67. EPTC at 3 and 6 lb a.i. an acre was phytotoxic to tobacco. Diphenamid at 4 to 12 lb a.i. an acre controlled weeds without adversely affecting tobacco growth. DCPA at 7 and 14 lb a.i. an acre on a coarse sand and 14 lb a.i. an acre on a sandy loam gave good control of weeds without adversely affecting the yield or quality of cured tobacco.