Various peach and apricot cultivars showed early and more uniform maturation and improved fruit colour following sprays of 2, 4, 5-TP, SADH or CEPA, but these effects were often accompanied by undesirable responses such as softening, cessation of growth, or abscission. Other substances, such as chlormequat, ABA and calcium nitrate delayed fruit maturation and increased firmness, whilst phenoxy auxins decreased fruit drop of peach and almond. The use of such compounds, together or in succession, offers possibilities for the practical control of stone fruit maturation.