Crabgrass Control Using Pre-Emergence Herbicides Applied in Tankmix with Humic Substances.

Pre-emergence herbicides were widely used in turfgrass management. Its efficacy can be affected by application rate and soil properties. The predominant soil factor affecting its efficacy is soil organic matter (SOM). Application of soil amendment which contain contains high level of organic matter content can affect herbicide efficacy by disturb herbicide dissipation dynamic and persistence in soils.  Applying SOM along with pre-emergence herbicide can be labor-saving and low environmental risk. It might be a good practice in integrated pest management.  In this study, we will apply four pre-emergence herbicides along with soil organic amendment on a 2-year established kentucky bluegrass stand and test the weed control efficacy. The turf quality will be evaluated by visiual rating. The herbicide residue in soil when 50% weed control is achieved will be correlated to total soil organic matter, herbicide application rate, and soil pH.