Abstract: The present invention provides methods of improving yields in crops of useful plants in need of yield improvement, such as maize, by applying a yield-improving amount of isoxadifen or an ester thereof to the plants, parts of plants, plant seeds or the area under cultivation. Also provided are methods of improving yields in crops of useful plants in need of yield improvement by applying a herbicidally effective amount of one or more herbicides and/or insecticides and yield-improving amount of isoxadifen or an ester thereof to the plants, parts of plants, plant seeds or the area under cultivation. Suitable herbicides can include, for example, rimsulfuron, nicosulfuron, foramsulfuron, diflufenzopyr, mesotrione or dicamba. One exemplary combination of a yield-improving application of isoxadifen with more herbicide is a yield-improving application of isoxadifen combined with diflufenzopyr and dicamba.