Fall application of prodiamine for spring crabgrass (Digitaria spp.) control

Fall application of a PRE herbicide offers professional lawncare applicators additional flexibility in scheduling necessary weed control operations. A 3-yr field study was established on common Kentucky bluegrass in Urbana, IL to examine the effectiveness of fall- or spring-applied prodiamine and DCPA for spring large and smooth crabgrass control. Prodiamine was effective for crabgrass control in turf (≥ 91% control) when applied in spring at ≥ 0.4 kg/ha or when it was applied in the fall at ≥ 0.6 kg/ha (≥ 82% control). In most cases, fall-applied prodiamine at the 0.8 kg/ha rate (≥ 91% control) controlled crabgrass as well as spring-applied DCPA at the 11.8 kg/ha rate (≥ 94% control). Little reduction in turf quality (≥ 8.3) occurred when prodiamine was applied in the fall at 0.8 kg/ha or less. Only when prodiamine was applied at 2.2 kg/ha was there significant quality loss (7.3) with spring applications. In a second experiment to evaluate split fall and spring prodiamine applications for crabgrass control, all split applications had 100% crabgrass control which was not significantly different from single applications of ≥ 1.4 kg/ha.