| Abstract/Contents: | Two experiments (one pre- and one postemergence) were conducted in both 1983 and 1984 to evaluate experimental herbicides for the control of smooth crabgrass in cool season turfgrasses. In 1983, the preemergenc e experiment was conducted on separate blocks of turf (one fine fescue and the other predominantly Kentucky bluegrass). On the fine fescue block, acceptable control (at least 85%) was attained by applying DCPA (all rates and formulations), bensulide 4E and 2.2S at 11.2 kg ai/ha, bensulide 7G at 11.2 and 14 kg ai/ha bensulide plus devrinol at both rates, bensulide plus oxadiazon, all rates of oxadiazon and pendimethalin applied alone, and benefin. Sequential applications of DCPA 75W caused severe injury to fine fescue. Severe injury also occurred when UC 77892 80W was applied. On the bluegrass block, DCP (all rates and formulations), bensulide 4E and 2.2S at 11.2 kg ai/ha, bensulide 76 at both rates, UC 77892 at the high rate, bensulide plus devrinol (granular forms), bensulide plus oxadiazon, all rates of oxadiazon and pendimethal applied alone, and benefin provided acceptable control. Sequential application of DCPA did not injure bluegrass nor did UC 77892. The poor control found for the Ando formulations (peltech oxadiazon) was probably due to the use of 50-mesh screens which may have trapped some material resulting in an underdosage. The postemergence test was initiated to compare crabgrass control from experimental compounds (fenoxyprop-ethyl, SC-1084, and UC-82042) with that from CAMA. Only CAMA provided acceptqble control, but it caused unacceptable control, but it caused unacceptable injury to a predominanatly fine fescue turf. At the time of application, all turf in the test was under moisture stress which affected the efficacy of fenoxyprop-ethyl. SC-1084 appeared to have potential as a rate effect was found and the turf was not injured. UC-82042 appeared to have little postemergence activity. In 1984, the premergence experiment was again conducted on separate blocks of turf. However, prior to application, both sites were verticut in two directions and over seeded with crabgrass from two sources (Rhode Island and Mississippi). On the fine fescue block, DCPA, both rates of bensulide 2.2S and the high rate of 4E, the 6.2 and 6.7 kg ai/ha rates of UCc 77892 4F, oxadiazon at 2.8 kg ai/ha, benefin, S-1280 and S-1319, pendimethalin, bensulide plus devrinol, and bensulide plus oxadiazon provided acceptable control. The powder and flowable formulations of UC 77892 caused severe injury to the fine fescue as did the bensulide plus EPTC treatment. On the bluegrass block, acceptable control was provided by DCPA, bensulide 7G at 11.2 kg ai/ha, UC 77892 4F at 6.6 kg ai/ha, benefin, S-1280 and S-1319, pendimethalin, and bensulide plus oxadiazon. The most consistent preemergence control in both test blocks in 1984 was found for DCPA and pendimethalin (S-1280 and S-1319). Bensulide plus EPTC caused severe injury to bluegrass. The postemergence test in 1984 was conducted on a mixed turf stand containing predominantly fine fescue. Soil moisture was adequate and all rates of fenoxyprop-ethyl provided excellent control from a single application. MSMA was improved by a sequential treatment, but did not acceptably control crabgrass. SC-1084 provided increased control at the higher rate without injury, but further testing is needed to establish a more efficacious rate. The broadleaf herbicide plus MSMA did not adequately control crabgrass from a single application. |
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