| Abstract/Contents: | "Field studies were conducted to evaluate preemergence herbicides for use in turfgrass. The evaluations focused on application rate, application time, formulations, turfgrass injury, and control of crabgrass (mixture of smooth and southern), or perennial ryegrass. Split applications of pendimethalin applied in March and May totaling 2.2 kg/ha provided crabgrass control equal to a single mid-March application of 3.3 kg/ha. Control with split applications in March-April-July of 1.1 + 1.1 + 1.1, 1.1 + 1.1 + 0, 1.7 + 1.7 + 1.7, 1.7 + 1.7 + 0, 1.7 + 1.7 + 1.1, 1.7 + 1.1 + 0, 1.7 + 1.1 + 0, 3.3 + 0 + 1.1, or 1.7 + 0, 1.1, or 1.7 kg/ha did not differ significantly 6 months after the initial application. However crabgrass control did not exceed 80% at this evaluation date unless the initial application was 3.3 kg/ha. In another experiment, with sequential applications at one or one half recommended rates in March followed by one half the initial rate 60 or 90 days later, crabgrass control was generally better if the sequential rate was made at 60 days. Oxadiazon, DCPA, bensulide, pendimethalin, and prodiamine formulated on fertilizer carriers provided equally effective crabgrass control when compared to the same rate of herbicide applied as a granular or spray to plots receiving the same amount of the base fertilizer. Crabgrass control with 1.1, 2.2, or 3.3 kg/ha oxadiazon (ME formulation) was less effective than equivalent rates of G or WP formulations. Crabgrass control with diflufenican was <40%. Preemergence applications were made in October of 0.6 or 1.1 kg/ha MON-15172, 2.2 kg/ha diclofop, 3.4 kg/ha oxadiazon, 1.7 + 1.7 kg/ha benefin + oryzalin, 2.0 or 3.4 kg/ha pendimethalin, 1.7 or 3.4 kg/ha oryzalin, 2.0 + 0.4 kg/ha pendimethalin + imazaquin, and 6.7 kg/ha napropamide provided >=80% control of perennial ryegrass (mixture of 42% 'Repell', 29.4% 'Cowboy', and 19.6% 'Pennant') overseeded on October 5, 1988 into common bermudagrass. Lower rates of pendimethalin, diclofop, oxadiazon, and benefin + oryzalin, as well as 3.4 kg/ha benefin, 13.4 kg/ha bensulide, 11.9 kg/ha DCPA, 4.5 kg/ha ethiozin, 0.8 kg/ha imazaquin, 4.5 kg/ha metolachlor, and 2.4 kg/ha simazine or lower rates provided <80% control of perennial ryegrass at 6 weeks after treatment. Lateral movement of herbicides that provided >= 80% perennial ryegrass control in the previous experiment on a 4:1 slope determined by perennial ryegrass bioassay (seeded down-slope) 8 weeks after treatment and overseeding were as follows: 0.6 kg/ha MON-15172, 0 cm; 3.4 kg/ha oxadiazon, 15.0 cm; 1.7 + 1.7 kg/ha benefin + oryzalin, 86 cm; 2.0 kg/ha pendimethalin, 0 cm; 3.4 kg/ha pendimethalin, 51 cm; 3.4 kg/ha oryzalin, 105 cm; and 2.0 + 0.4 kg.ha pendimethalin, imazaquin, 15 cm." |
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