Dissipation and Efficacy of Pendimenthalin as Affected by Dose and Application Timing for Crabgrass (Digitaria sp) Control in a Turfgrass Environment in Ohio.

The main objective of this research is to correlate crabgrass control with the residue level of Pendimenthalin applied at three rates (maximum label rate applied twice at 30 days interval, half label rate applied twice at 30 days interval and maximum label rate applied once) and application timing (Autumn and Spring).The design of the experiment was completely randomized with three replicates per treatment. The whole experimental area was reseeded with crabgrass (Digitaria sp) seed before herbicide application. Soil temperature and moisture were measured during the experiment. Soil samples were taken from each individual plot: 0, 4, 8, 16, 32, 36, 40, 48, 64 and 128 days after treatment. Each soil sample was divided in three sections: verdure-thatch, 0 to 5 cm and 5 to 10 cm. Herbicide was extracted following Gardner (2000) protocol and quantified using a gas chromatograph. Preliminary data has been obtained for Pendimethalin applied in Autumn 2007 and Spring 2008. At 0 days after the application 88% of the herbicide was detected on the verdure-thatch layer with a average recovery rate of 90% and a detection limit of  0.1 ppm.