The present invention provides a novel composition and method for controlling, killing or inhibiting the growth of bryophytes (e.g. mosses and liverworts). It is applicable to the remediation of these organisms in, gardens, orchards or agricultural land, or forests and upon higher plants without substantial detriment to grasses, trees or most broad leaf plants. The novel composition is a combination of an effective amount of finely ground calcium-rich compound suspended in a horticulturally or agriculturally acceptable diluent, and/or binder/carrier. In addition to being a carrier for the calcium-rich compound the binder also acts to bind fine soil particles, helping to conserve irrigation water and to reduce soil erosion. The binder can further incorporate further components such as wetting agents and penetration agents (both of which are broadly referred to as surfactants), and translocation agents, adhesives, emulsifiers, suspending agents, thickeners, synergists other moss killers or biocides, such as herbicides, fungicides, bactericides, insecticides and weed killers, hormones, plant growth regulators or plant nutrients.