In an electrostatographic process and apparatus a replenishment device adds toner particles to a development station that includes a developer comprising a mixture of toner particles and carrier particles. A reference parameter that is used in control of aim point of toner concentration in the mixture is set to an initial value until about a midlife of the developer is reached. Once the midlife of the developer is reached there are provided programmed step adjustments in the reference value in accordance with further increases in life of the developer to thereby control replenishment of toner particles so that control of charge to mass of the toner particles in the mixture is provided to reduce a tendency of dusting by the toner particles of the mixture due to age of the developer.