Q: What are the benefits of applying a dormant spray to deciduous fruit trees? --G.A., Tarzana A: Dormant sprays have been recommended for many years to control fungus diseases that attack the foliage, twigs and fruit of deciduous fruit trees such as peach, apricot and nectarines. Without dormant-spray applications, you increase the chances of losing leaves and fruit. Severe attacks of peach leaf curl fungus usually reduce the formation of fruit buds. Timing of dormant-spray applications is very important to the control of these diseases, and the disease involved dictates the timing: Peach leaf curl can almost always be prevented by applying lime sulfur just before the buds swell in early spring. Spraying at that time is too late to control peach blight and too early to combat brown rot. Peach-blight control usually requires an initial fall treatment. Sprays for brown rot produce better results if they're applied after the buds have begun to open--the so-called pink bud stage. Gathering fallen leaves from the ground and disposing of them also will help minimize disease.