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This article in AJ

  1. Vol. 69 No. 3, p. 505-508
    Received: Aug 20, 1976

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Use of Paraquat in Establishing Dallisgrass and Bahiagrass1

  1. Gerald W. Evers2



Plantings of warm season perennial grasses from seed are slow to establish and often fail because of competition from fast growing weeds. Paraquat (1,1′-dimethyl-4,4′-bipyridinium ion), a fast acting contact herbicide, has been used successfully in establishing cool season grasses from seed for seed production. Purpose of this study was to determine if the application of paraquat after planting, but before the desired grasses emerged, would reduce weed competition and promote rapid establishment of the desired grasses. In the spring of 1974 and 1975 ‘Pensacola’ bahiagrass (Paspalum notatum Flugge) and dallisgrass (Paspalum dilatatum Poir.) were planted on a prepared seedbed on a Morey fine-silty loam [Typic Argiaquolls, fine-silty, mixed (noncalcareous), thermic]. Experimental design was a split, split plot with four replications for each of the two grasses. Main plots were paraquat applied at 0.56 kg in 154 liters of water/ha at random time intervals after planting. Subplots were 12 fertilizer treatments consisting of a four by three factorial of 0, 22.4, 44.8 and 67.3 kg/ha of phosphorus and 0, 33.6, and 67.3 kg/ha of nitrogen applied on the day of planting. Plant densities were determined at two or three locations in each plot by randomly throwing a 0.09 m2 quadrant on to the plot. Dry matter yields were determined by cutting a 1 × 4.2 m area from the center of each plot to a 4 cm height. Paraquat was most effective when applied as late as possible but before bahiagrass and dallisgrass plants emerged. Dry matter yields of bahiagrass were tripled and dallisgrass doubled. Under the climatic conditions and soil type in this study, optimum time for applying paraquat to dallisgrass plantings was 10 but no later than 14 days and to bahiagrass plantings 14 to 21 but no later than 28 days after sufficient rainfall for grass seed germination. No consistent benefit was produced by any of the fertilizer treatments.

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