Reduced Preemergence Herbicide Rates for Large Crabgrass (Digitaria sanguinalis) Control in Six Tall Fescue (Festuca arundinacea) Cultivars

Abstract

A field experiment was conducted over a 2-yr period to determine the effects of reduced PRE herbicide rates on large crabgrass infestation in six tall fescue cultivars. With the exception of oryzalin and benefin plus oryzalin in 1993, there was no cultivar by herbicide interaction for large crabgrass infestation when final ratings were made in 1993 and 1994. This interaction was caused by moderate to severe turfgrass injury that thinned the turf. When cultivars were disregarded, prodiamine was the only herbicide applied at one-third recommended rate in 1993 that effectively suppressed large crabgrass for the full season. Prodiamine and dithiopyr were the only PRE herbicides applied at one-third recommended rates for two consecutive years that effectively suppressed large crabgrass in 1994. Two-thirds recommended rate was needed for two consecutive years for oxadiazon, pendimethalin, oryzalin, benefin plus oryzalin, and benefin plus trifluralin to maintain optimum large crabgrass suppression in 1994.