| Abstract/Contents: | "Two studies were initiated, one, in a fallow soil area and the other in a Kentucky bluegrass (Poa pratensis L.) lawn. Granular materials were applied by hand and others as sprays (75 to 150 GPA) to four replicated plots in each study. The herbicides and rates are shown in Table 1. Sixteen treatments were applied Aug 29, 1986 to soil seeded with dandelion (Taraxacum vulgare L.). Henbit (Lamium amplexicaule L.) and common chickweed [Stellaria media (L.) Vill.] from seed in the soil started to emerge in two days while dandelion started several days later. Control estimates were made Sept 24 to Oct 2, 1986. Herbicides were reapplied (Apr 10-16, 1987) to two weed-free replications (glyphosate used Oct 86). A few 3-day-old seedlings were present but most germination of henbit, common chickweed, purslane speedwell (Veronica peregrins L.) and Oxalis spp. occurred later. Control estimates were made Jun 9-22. The weeds were killed with glyphosate and control of Veronica, which germinated Aug-Sept, was made Oct 14. In the lawn study five treatments were applied on Sept 16, 1986. Dandelion seed was broadcast over the area in Dec. Five repeat and 12 new treatments were made on Aug 18, 1986, Aug 3 and Oct 14, 1987. The results in Table 1 show that some herbicides provided excellent weed control (85-100%). None of the treatments caused objectionable turf injury. Henbit control in soil (Sept-Oct) from August treatment was excellent with benefin + trifluralin, DCPA, oxadiazon, pendimethalin and prodiamine. August residues of isoxaben and oxadiazon provided control of Apr-Jun henbit. With retreatment in April all but four herbicides provided excellent results. Chickweed control in soil (Sept-Oct) from August treatment was excellent with DCPA and pendimethalin. August residues of isoxaben and prodiamine provided Apr-Jun chickweed control. With retreatment in April excellent control was provided by bensulide, isoxaben, pendimethalin and prodiamine. Dandelion control in soil (Sept-Oct) from August treatment was excellent with 2,4-D, 2,4-D plus dichlorprop or triclopyr or mecoprop + dicamba, 2,4-D/MCI 60 (melamine fertilizer) at rates of 1.8 or 2.7 lbs, DCPA, oxadiazon and pendimethalin. Veronica which germinated Apr-Jun in soil was controlled by August residues of isoxaben. April retreatment of 2,4-D/MCI 60 at 2.7 lb rate, 2,4-D + triclopyr, bensulide, prodiamine, isoxaben, oxadiazon and pendimethalin provided excellent results. Control in October was provided by the latter three residues. Oxalis emerging in soil during Apr-Jun was controlled by August residues of oxadiazon. April retreatment of 2,4-D/MCI 60 at 2.7 lb rate, isoxaben, oxadiazon, pendimethalin and prodiamine were effective. In the lawn study most dandelion germination occurred from mid-July to mid-Sept 1987. Repeat treatments (Sept 86 + Apr 87 + Aug 87) of 2,4 d, 2,4-D/MCI 60 and granular 2,4-D + mecoprop + dicamba provided excellent dandelion reduction. Of the preemergent herbicides, applied Apr + Aug 87, the most effective were pendimethalin, isoxzben + benefin + trifluralin, oxadiazon, isoxaben + benefin and DCPA. The least effective herbicides were benefin, siduron, prodiamine, bensulide, benefin + trifluralin and isoxaben." |
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