by Andrew Johnson, Marcelo Moretti, and Brad Hanson; UC Davis Weed Science (Article originaly posted at UC Weed Science) Several field experiments were conducted to evaluate the performance of pre-emergence herbicides, herbicide rates, and tankmix combinations at different locations in the Central Valley of California and to compare the efficacy of burndown herbicides in mixture with different pre-emergence herbicides. The same treatments were used in three studies located in Fresno, Merced, and Colusa counties. Only data from the Merced county site is presented due to low weed densities at the Fresno and Colusa county sites.