Dinitroaniline herbicides are major herbicides used to control annual grass weeds in cool-season turfgrasses. At least three herbicides, benefin, pendimethalin, and trifluralin are labeled preemergence to control weeds in established turfgrass. Prodiamine could be a competitive product. Benefin at 2.2 to 3.4 kg ai/ha, pendimethalin at 1.7 to 3.4 kg ai/ha, prodiamine at 0.6 to 1.7 kg ai/ ha, and benefin plus trifluralin at 1.1 plus 0.6 to 2.3 plus 1.1 kg ai/ha effectively control many annual grass weeds, including large and smooth crabgrass, yellow and green foxtail, barnyardgrass, goosegrass, fall panicum, and annual bluegrass. Most dinitroaniline herbicides provide residual preemergence weed control for the entire growing season. In general, Kentucky bluegrass, perennial ryegrass, tall fescue, red fescue, and other cool-season turfgrasses tolerate most of these herbicides, although higher-than-normal rates of any dinitroaniline herbicide could restrict root growth and cause stand thinning in turfgrass species.

Field research from 1986 to 1988 evaluated control of alfalfa, dandelion, orchardgrass, and annual weeds in corn with sequential herbicide treatments. Glyphosate applied the previous fall controlled 95% or more of the dandelion and orchardgrass before postemergence treatments. Atrazine applied early preplant or with paraquat the day before planting only partially controlled the perennial species. Atrazine applied postemergence usually controlled vegetation escaping initial treatment except orchardgrass following the atrazine treatments. Adding tridiphane increased weed control with atrazine or cyanazine applied postemergence only when fall panicum was present. Herbicides applied postemergence increased corn yield compared to the initial treatments alone, and few differences among postemergence treatments were observed. Sequential treatments which included glyphosate applied in the fall controlled 82% or more of each perennial species before the next growing season. Orchardgrass control was 81% or less the following spring when the initial treatment was atrazine or atrazine plus paraquat.

Experiments were conducted to investigate the interactions of tank-mix combinations of sethoxydim plus the sodium salt of bentazon, the sodium salt of acifluorfen, fomesafen, imazaquin, or the ethyl ester of chlorimuron. Antagonistic interactions were observed with tank-mixes of sethoxydim plus bentazon, imazaquin, or chlorimuron applied for fall panicum, large crabgrass, and goosegrass control in field experiments. Antagonism was observed in greenhouse experiments with tank-mixes of sethoxydim plus bentazon or imazaquin applied to goosegrass. Bentazon, acifluorfen, and fomesafen reduced 14C-sethoxydim uptake by large crabgrass. However, imazaquin and chlorimuron did not affect 14C-sethoxydim uptake. In field experiments, no interactions occurred with tank-mixes of sethoxydim plus any of the broadleaf weed control herbicides applied to entireleaf or tall morningglory.

Influences of a hairy vetch cover crop and residual herbicides were examined in field corn in 1991 and 1992. Hairy vetch was seeded in mid-August and killed the following May with tillage, mowing, or glyphosate plus 2,4-D (no-till). These cover crop management systems were compared with a no-cover treatment. Residual herbicides including atrazine plus metolachlor applied PRE at three rates and nicosulfuron plus thifensulfuron applied POST at a single rate were compared within cover crop management systems. All cover crop management systems effectively controlled hairy vetch except mowing in 1992. The corn population was reduced in mow treatments containing uncontrolled vetch. Hairy vetch mulch suppressed some weeds in the no-till treatments in 1991, but more annual grass was noted late in the season with no-till into hairy vetch than with the no-cover treatments in 1992. Residual herbicide performance was similar across cover crop management systems, except for fall panicum control which decreased in some no-till systems. Unlike soil-applied herbicides, performance of POST herbicides was unaffected by cover crop management systems.

Research in Kansas from 1983 to 1986 evaluated early preplant (30 to 45 days) and late preplant (10 to 14 days) herbicide treatments for weed control before ridge-till planting in a soybean and sorghum rotation. Control of fall panicum and common lambsquarters at planting time averaged at least 95% for all early preplant and 92% for late preplant treatments. Where no preplant treatment was used, heavy weed growth in spring delayed soil dry-down, which resulted in poor ridge-till planting conditions and reduced plant stands, and ultimately reduced sorghum grain yields by 24% and soybean yields by 12%. Horsenettle population declined significantly, and honeyvine milkweed population increased. Smooth groundcherry populations fluctuated from year to year with no overall change.

Field studies were conducted over a four-year period to determine the weed control efficacy of ICIA-0051 and SC-0774 in no-tillage and conventional corn. Treatments consisted of both pre- and postemergence applications of ICIA-0051, alone and in combination with atrazine, and preemergence applications in combination with metolachlor. SC-0774 was applied preemergence, alone and in combination with atrazine. Results indicated good control of triazine-resistant (TR) smooth pigweed and other annual broadleaf weeds present with no adverse effects on crop vigor and yield with ICIA-0051. Generally, the addition of atrazine to ICIA-0051 improved weed control. SC-0774 provided good control of fall panicum, but generally poorer and less consistent control of giant ragweed, common ragweed, common lambsquarters, and ivyleaf and tall morningglory species.

A 2-yr field study was conducted to evaluate the efficacy of ICIA-0051 for the control of annual grass and broadleaf weed species in conventional tillage corn. Treatments consisted of postemergence applications of ICIA-0051 alone and in combination with cyanazine or atrazine. ICIA-0051 at 0.6 kg ha-1 alone and in combination with cyanazine or atrazine at 1.1 kg ha-1 controlled large crabgrass, yellow foxtail, fall panicum, common lambsquarters, and redroot pigweed effectively (over 90%). The addition of cyanazine or atrazine at 1.1 kg ha-1 to the lowest rate (0.3 kg ha-1) of ICIA-0051 also improved large crabgrass, yellow foxtail, and fall panicum control by 9, 7, and 26%, respectively. None of the treatments of ICIA-0051 except the highest rate (1.1 kg ha-1) reduced either silage or grain yields of corn.

The interaction of imazethapyr and selected graminicides on annual grass control was studied in field experiments. Tank-mix combinations of imazethapyr with clethodim, fluazifop-P, quizalofop, or sethoxydim resulted in an antagonistic interaction. Control of large crabgrass, fall panicum, and broadleaf signalgrass by each graminicide decreased when tank-mixed with imazethapyr as compared with each graminicide applied alone. Sequential applications of imazethapyr, relative to each graminicide, successfully overcame the antagonism. Imazethapyr applied 5 d before or 1 d after each of the graminicides did not decrease grass weed control compared with each graminicide alone. Imazethapyr applied 3 or 1 d before, or the same day as the graminicides, generally decreased grass weed control.